CHAPTER 10

 

 

Walking Sticks Crickets, Praying Mantis, Locusts and Others.

Grasshoppers. About 8,000 species of grasshoppers are known worldwide; more than 600 species occur in North America alone. The term, shorthorned grasshoppers, refers to the fact that all individuals of this family have short antennae that do not exceed the combined length of the head and thorax (Figure 11A). All species are phytophagous, but only a few increase to numbers large enough to become major pests. Grasshoppers typically have a single generation per year and pass the winter as egg pods in the soil. Some species of these grasshoppers are quite colorful (Figure 11B). One of the more famous shorthorned grasshoppers is the lubber grasshopper. This African species is commonly used for decades for classroom dissections (Figure 11C).

 

 

Figure 11A. A shorthorned grasshopper illustrating the short antennae.

The term locust is used to refer to some species of migratory shorthorned grasshoppers. A few species of locusts are the most important agricultural pests in the world. They have destroyed crops from Biblical days to the present time, with every continent plagued by migratory locusts. These insects are especially prevalent in semi-arid climates.

 

 

Figure 11B. A harlequin shorthorned grasshopper from Arizona-a common migratory species.

Image compliments of Bob Spencer.

 

 

Figure 11C. A lubber grasshopper that is commonly used for classroom dissections. Also a migratory species.
Image compliments of Bob Spencer.

 

A few species of locusts are the most important agricultural pests in the world (Figure 6).  They have destroyed crops from Biblical days to the present time, with every continent plagued by migratory locusts.  The Desert Locust is one of about a dozen species of short-horned grasshoppers (Acridoidea) that are known to change their behavior and form swarms of adults or bands of hoppers (wingless nymphs). The swarms that form can be dense and highly mobile. The Latin name for Desert Locust is Schistocerca gregaria (Forskal). During quiet periods (known as recessions) Desert Locusts are usually restricted to the semi-arid and arid deserts of Africa, the Near East and South-West Asia that receive less than 200 mm of rain annually. This is an area of about 16 million square kilometers, consisting of about 30 countries. During plagues, Desert Locusts may spread over an enormous area of some 29 million square kilometers, extending over or into parts of 60 countries. This is more than 20% of the total land surface of the world. During plagues, the Desert Locust has the potential to damage the livelihood of a tenth of the world's population.

There is no evidence that Desert Locust plagues occur after a specific number of years. Instead, plagues develop intermittently. Plagues of locusts have been reported since the Pharaonic times in ancient Egypt. During this century, Desert Locust plagues occurred in 1926-1934, 1940-1948, 1949-1963, 1967-1969 and 1986-1989. A Desert Locust lives a total of about three to five months although this is extremely variable and depends mostly on weather and ecological conditions. The life cycle comprises three stages: egg, hopper and adult. Eggs hatch in about two weeks (the range is 10-65 days), hoppers develop in five to six stages over a period of about 30-40 days, and adults mature in about three weeks to nine months but more frequently from two to four months.

Desert Locust females lay eggs in an egg pod primarily in sandy soils at a depth of 10-15 centimeters below the surface. A solitary female deposits about 95-158 eggs whereas a gregarious female lays usually less than 80 eggs in an egg pod. Females can lay at least three times in their lifetime usually at intervals of about 6-11 days. Up to 1,000 egg pods have been found in one square meter.

Desert Locusts usually fly with the wind at a speed of about 16-19 km/h until they encounter a storm, at which point they lay eggs in the ground.  The rainfall in this area will provide plant growth for the next generation of locusts.  Migration is therefore a mechanism to ensure population survival in semi-arid climates where rainfall is irregular and localized.

Locusts can stay in the air for long periods of time. For example, locusts regularly cross the Red Sea, a distance of 300 km. In the past there have been some spectacular and very long distance swarm migrations, for example from North-West Africa to the British Isles in 1954 and from West Africa to the Caribbean, a distance of 5,000 km in about ten days in 1988. Solitary Desert Locust adults usually fly at night whereas gregarious adults (swarms) fly during the day.

Locust swarms can vary from less than one square kilometers to several hundred square kilometers. There can be at least 40 million and sometimes as many as 80 million locust adults in each square kilometer of swarm. Early in 1994, air reconnaissance observations registered 50 swarms that invaded Kenya. The total number of individual insects in these swarms was estimated to exceed 50 billion locusts, weighing about 100,000 tons.  With a very large swarms this could equate to 40,000 million locusts. A Desert Locust adult can consume roughly its own weight in fresh food per day that is about two grams every day.  On their way to oviposition (egg laying) sites, locust swarms frequently descend on agriculture crops and inflict incredible damage.  A swarming cloud of millions of individuals will occasionally land in mass and devour all vegetation in sight, including entire crops.  Because these attacks are typically instantaneous and overwhelming, there is very little farmers can do on their own.

rage swarm (or about one ton of locusts) eats the same amount of food in one day as about 10 elephants or 25 camels or 2,500 people.  Based on simple math the Kenyan locus that year consumed enough food to feed 1,000,000,000 people.

When conditions are favorable for reproduction, locust numbers increase and when they are not, numbers decrease either by natural mortality or through migration. For the Desert Locust, favorable conditions for breeding are moist, sandy or sand/clay soil to depths of 10-15 cm below the surface,  some bare areas for egg-laying, and green vegetation for hopper development. Often favorable conditions may exist in the desert but there are no locusts present. Therefore, the presence of moist soil and green vegetation does not automatically mean that there are locusts around

As Desert Locusts increase in number and become more crowded, they change their behavior from that of acting as an individual (solitarious) insect to that as acting as part of a group (gregarious). The appearance of the locust also changes: solitary adults are brown whereas gregarious adults are pink (immature) and yellow (mature). Up until 1921, it was thought that the Desert Locust was actually two different species of locusts.

Although the Desert Locust is considered to be the most important species of locust due to its ability to migrate over large distances and rapidly increase its numbers, there are several other important species of locusts throughout the world:

At present the primary method of controlling Desert Locust swarms and hopper bands is with mainly organophosphate chemicals applied in small concentrated doses (referred to as ultra low volume (ULV) formulation) by vehicle-mounted and aerial sprayers and to a lesser extent by knapsack and hand-held sprayers. Control has to be over huge areas as some of the swarms can reach over several hundred square miles and contain billions of these insects. This typically is accomplished by ultra low volume (ULV) aerial spraying with technical malathion.  Small planes that spray pesticide mixed with water accomplish normal agricultural aerial spraying.  Several gallons of the mixture are sprayed per acre, with each flight covering only 10 to 20 acres before the plane must land and reload spray materials.

 

ULV spraying is unique, in that 'technical,' or undiluted malathion is sprayed at the rate of one-to-two ounces per acre.  Because WW II bombers are used they can spray huge areas before having to reload.  When possible, these ULV applications are aimed at the migrating nymphal forms before the locusts become airborne.  Because malathion is a selective insecticide, it has essentially no effect on nontarget organisms (such as wildlife, domestic or farm animals, and humans).

Locust survey and control are primarily the responsibility of the Ministry of Agriculture in locust affected countries and are operations undertaken by national locust units. There are also several regional locust organizations that assist with survey and control operations. During times of outbreaks and plagues, external assistance from the donor community and other international organizations is usually required.

Extensive research is in progress on biological control and other means of non-chemical control of locusts. The current focus is primarily on pathogens and insect growth regulators. Thus far control by natural predators and parasites is limited since locusts can quickly migrate away from most natural enemies. Although giant nets, flamethrowers, lasers and huge vacuums have been proposed in the past, these are not in use for locust control. People and birds often eat locusts but usually not enough to significantly reduce population levels over large areas.

Weather satellites and other satellites used to monitor the environment cannot detect locust individuals or swarms. However, the highly sophisticated satellites used by the military can indeed detect locusts but these images are not available. Even if they were, it is unlikely that national and international locust organizations would have the ability to interpret the hundreds of images that would be produced on a daily basis

There are many reasons as to why it is difficult to successfully combat the Desert Locust. Some of these are: (1) the extremely large area (16-30 million sq. km) within which locusts can be found, (2) the remoteness and difficult access of such areas, (3) the insecurity or lack of safety (such as land mines) in some areas, (4) the limited resources for locust monitoring and control in some of the affected countries, (5) the undeveloped basic infrastructure (roads, communications, water and food) in many countries, (6) the difficulty in maintaining a sufficient number of trained staff and functioning resources during the long periods of recession in which there is little or no locust activity, (7) political relations amongst affected countries, (8) the difficulty in organizing and implementing control operations in which the pesticide must be applied directly onto the locusts, and (9) the difficulty in predicting outbreaks given the lack of periodicity of such incidents and the uncertainty of rainfall in locust areas.

People in several countries collect locusts using large nets and by other means. Locusts are usually stir-fried, roasted or boiled and eaten immediately or dried and eaten later (see some recipes below). Locusts are rich in protein. During periods of increased locust activity, piles of dead locusts can be found in the market places of many locust affected countries. About 62% of the dry weight of an adult Desert Locust consists of proteins, 17% as fats, and the remainder as inorganic constituents (Si, Cu, Fe, Mn, Na, K, Ca, Mg, Ti, Ni, P, S).

One of the mandates of the Food and Agriculture Organization (FAO) of the United Nations is to provide information on the general locust situation to all interested countries and to give timely warnings and forecasts to those countries in danger of invasion. Therefore, FAO operates a centralized Desert Locust information service within the Locust Group at FAO Headquarters, Rome, Italy. All locust affected countries transmit locust data to FAO who in turn analyze this information in conjunction with weather and habitat data and satellite imagery in order to assess the current locust situation, provide forecasts up to six weeks in advance and issue warnings on an ad-hoc basis. FAO prepares monthly bulletins and periodic updates summarizing the locust situation and forecasting migration and breeding on a country by country basis. These are distributed by email, fax, and post. All locust information is archived at FAO Headquarters and some of this is available on the Internet.

Furthermore, FAO provides training and prepares publications on various aspects of locusts. FAO undertakes field assessment missions and coordinates survey and control operations as well as assistance during locust plagues.

Of course when a particular area is heavy hit by these crop destroying insects. Here are a few local recipes from locust-affected countries.

Tinjiya (Tswana recipe): remove the wings and hindlegs of the locusts, and boil in a little water until soft. Add salt, if desired, and a little fat and fry until brown. Serve with cooked, dried mealies (corn).

Sikonyane (Swazi recipe): prepare embers and roast the whole locust on the embers. Remove head, wings, and legs, in other words, only the breast part is eaten. The South Sotho people use locusts especially as food for travelers. The heads and last joint of the hindlegs are broken off and the rest laid on the coals to roast. The roasted locusts are ground on a grinding stone to a fine powder. This powder can be kept for long periods of time and is taken along on a journey. Dried locusts are also prepared for the winter months. The legs, when dried, are especially relished for their pleasant taste.

Cambodia: take several dozen locust adults, preferably females, slit the abdomen lengthwise and stuff a peanut inside. Then lightly grill the locusts in a wok or hot frying pan, adding a little oil and salt to taste. Be careful not to overcook or burn them.

Barbecue (grilled): prepare the embers or charcoal. Place about one dozen locusts on a skewer, stabbing each through the centre of the abdomen. If you only want to eat the abdomen, then you may want to take off the legs or wings either before or after cooking. Several skewers of locusts may be required for each person. Place the skewers above the hot embers and grill while turning continuously to avoid burning the locusts until they become golden brown.

In general, locusts, grasshoppers and cockroaches are common insect allergens. Locust pheromones or hormones produced during mating, in combination with scales that come off the wings and cuticle of the locust, increased amounts of dust in the air and perhaps other chemicals (such as phenols that are released from the breakdown of vegetation), can act as allergens to humans and trigger allergic reactions primarily in people already susceptible to asthma. This form of respiratory illness is often referred to as Lung Eczema or Laboratory Animal Allergy. Exposure is usually unintentional (nuisance) or through professional activities (insect rearing facilities and laboratories where there are strict rules on wearing face masks). Asthma can appear one to two years after initial exposure.

 

 

 

Katydids, Longhorned Grasshoppers. As indicated by their name, members of this family have elongated antennae that often exceed their entire body length (Figure 11D). In most cases the front wings of these insects are leaf-like in appearance. Of course, the advantage of this is to blend in with the leaves of their host-plants and thus avoid potential predators. Even though these insects occasionally are found feeding on agricultural plants, they rarely, if ever, reach numbers high enough to become major pests.

 

Figure 11D. Top.  A typical longhorned grasshopper or katydid with elongate antennae and leaf-like front wings.  Bottom. Immature longhorned grasshopper-same species as adult.

 

Some of the mimicry displayed by these insect is amazing. Can you find the dead leaf katydid in Figure 11E?

Figure 11E. A katydid exhibiting a high degree of mimicry. Image courtesy of Peter Chew.

I was once collecting insects in Guatemala and happened to walk by a plant that was severely damaged by some caterpillars with large holes eaten in the leaves.  Out of the corner of my eye one on the leaves appeared to be walking.  On close inspection it was a katydid.  Of course the wings were leaf-like but amazingly its wings also appeared that they had been partially consumed with large holes in them.  More to my astonishment the wings also exhibited several symptoms of bacterial leaf spot-a plant disease.  Bacterial leaf spot on leaves initially starts out as small brown rotting spots.  As the disease progresses the brown spots turn into small holes.  Here was an insect that had wings that looked like leaves that had been feed upon by another insect and had several symptoms of plant disease-all mimicry.  Nature is amazing.  I wish I had taken and picture of that to show you.

                                                                                                                     Mormon Cricket-Anabrus simplex

Mormon Cricket-Anabrus simplex. This one of the more famous of the longhorned grasshoppers. Mormon crickets have variable coloration. The overall color may be black, brown, red, purple or greens.  They may undergo morphological changes triggered by high population densities, similar to those seen in locusts. The best-attested change is coloration: single individuals typically have drab coloration while swarming individuals are often brightly colored. The "shield" (actually vestigial wings) behind the head may have colored markings. The abdomen may appear to be striped. Females have a long ovipositor, which may be mistaken for a stinger. Both sexes have long antennae.

Life Cycle. Mormon cricket eggs mostly hatch the spring after they are laid, although in some high-elevation areas eggs may take two years to hatch. Hatching begins when soil temperatures reach 40 °F (4 °C). The nymphs pass through seven instars before reaching the adult stage, typically taking 60 to 90 day. The female lays her eggs by thrusting her ovipositor deep into the soil. Females can deposit about one hundred eggs each s.

These insects exhibit rather unusual breeding behaviors. Breeding begins within 10 to 14 days of reaching the adult stage. The male passes a large spermatophore (sperm packet) to the female, which can be up to 27% of his body weight. The spermatophore is mostly food for the female to consume but also contains sperm to fertilize her eggs. The value of this nuptial gift is such that swarming-phase females compete for males. This sexual role-reversal is not seen in solitary-phase females.

The Mormon cricket exists in populations of relatively low density throughout most of its range. However, at certain times and places, population explosions or infestations occur in which large numbers of the cricket form roving bands. These bands may include millions of individuals and have a population density of up to 100 individuals per square meter. These infestations may last years or even decades, and are characterized by a gradual increase and then decrease in population. The factors that trigger these infestations are poorly understood, but are thought to be weather-related. When a large band crosses a road it can cause a safety hazard by causing distracted revulsion on the part of the driver, and by causing the road surface to become slick with their fluids.

Damage. The Mormon cricket prefers to eat forbs, especially cultivated crops such as alfalfa, and vegetables. Grasses and shrubs such as sagebrush are also eaten. Insects, including other Mormon crickets, are also eaten, especially individuals that have been killed or injured by automobiles or insecticides. Although Mormon crickets are primarily phytophagus (feed on plants) they will fed on protein, including road kill, dead insects and even become cannibalistic when swarming. Some research indicates the Mormon cricket's cannibalistic behavior causes these crickets to swarm and move in band.  The reasoning being that rickets attack the cricket in front of them every few seconds and must move constantly forward to avoid attacks from behind.

                                               Mormon crickets eating another Mormon cricket. Right swarming Mormon crickets.  Image courtesy Katie Madonia. 

 

Control. Mormon crickets are preyed upon by a wide variety of birds and mammals. These predators include California Gulls, crows, coyotes and various rodents. They were also eaten by Native Americans. There are no predators that specialize on Mormon crickets, which may be explained by the cricket's migratory habits and large population fluctuations.

The most common chemical control method used is carbaryl (typically sold as "Sevin") bait. This bait kills both the Mormon crickets that eat the bait, and the crickets that eat crickets that eat the bait. Insecticides applied directly to crops may kill the insects, but due to the large size of swarms this method usually does not save the crop from being destroyed.

As Mormon crickets are flightless, physical barriers may be effective. Barriers should be at least two feet high and made of a smooth material. Recently, residents of some small towns have been effectively using boom boxes and sound systems playing hard rock music to divert the moving swarms away from crops and houses, as the insects seem to be deterred by it, although it is unknown if the result is due to the music or the heavy vibrations.

Historical Significance.  After Brigham Young led the first band of Latter-day Saints into what is now Salt Lake City, Utah, the pioneers had the good fortune of a relatively mild winter. Although late frosts in April and May decimated some of the crops, the Mormons seemed to be well on their way to self-sufficiency. Unfortunately, swarms of insects appeared in late May.

These insects, now called "Mormon crickets" are unable to fly, but instead travel in huge devouring hordes. Mormon crickets eat all plant material in their path, but they also cannibalize any insects that die on the way. They're known to cyclically swarm in some areas of the Mountain West, especially in Utah and Nevada. These bugs understandably terrified the pioneers. Stomping on the pests did not dissuade them from entering farms. Indeed, other crickets would advance to eat the remains of their brothers. Mormons, prolific journal writers, often cast this disaster in Biblical terms like the 8th plague of locusts.

According to some pioneers' accounts, legions of gulls appeared by June 9, 1848. Many letters and diaries recount that these birds, native to the Great Salt Lake, ate mass quantities of crickets, drank some water, regurgitated, and continued eating more crickets. Ornithologists don't regard this as particularly unusual because the seagulls around the Great Salt Lake often eat insects in the adjacent valleys, but some pioneers saw the gulls' arrival as a miracle, and the story was recounted from the pulpit by church leaders such as Orson Pratt and George A. Smith. (Pratt 1880, p. 275; Smith 1869, p. 83) The traditional story is that the seagulls annihilated the insects, ensuring the survival of some 4,000 Mormons who had traveled to Utah. For this reason, Seagull Monument was erected and the California gull is the state bird of Utah.

Walking Sticks. There are about 700 species of walking sticks worldwide. Almost all are tropical in origin with relatively few living naturally in the United States. Most species of this family mimic twigs in both body shape and color (Figure 11F). However, there are some tropical species that are quite leaf-like in appearance. Most walking sticks are quite large, with some Thai species reaching 13 inches in length (longest insect species).

 

 

Figure 11F. A typical twig-like walking stick.

These insects have developed a variety of protective mechanisms. An example of these behaviors is exhibited by the large Phyllium stick insect from Malaysia. This stick is flattened and leaf-like in appearance (Figure 11G). In fact, when the authors have kept several together in a terrarium, one or two eventually were partially eaten by the other sticks, undoubtedly one confusing the other with leaves, their normal diet. As do most sticks, these insects rarely move; when they do, it is quite slow. There is no advantage in moving rapidly while mimicking a leaf or twig.

Figure 11G.  A Phyllium walking stick from Malaysia.

Heteropterix sp. (Figure 11H) has a whole bag of defensive mechanisms.  It blends in with its host plant as it is flattened, green and somewhat leaf-like.  In addition it will use its hind legs which are armed with sharp spines in order to fend off potential predators. These spines are capable of drawing blood when the insect is handled carelessly. At the same time that this stick attacks with its hind legs, it will spread its hind wings, exposing bright red underwings and produce a hissing noise (caused by scraping wings) in an attempt to startle its attacker. Many insects commonly use flashing bright colors. It is thought that the sudden display of bright color will startle a potential predator. Normally bright colors in nature are a sign of some type of danger (warning coloration). The hissing is assumed to mimic that of a snake. If these mechanisms fail, it will fall to the ground and play dead. Very few predators will attack dead insects.

 

 

Figure 11H. A female Heteropterix walking stick from Malaysia.

Another aggressive species is Eurycantha sp. from Papua New Guinea (Figure 11I). This species has a pair of very large spines on its hind legs that it readily uses when threatened. These spines are so large on the males that the natives of this country carve them to make fish hooks. As one might expect, this species commonly is eaten by the natives and is said to taste like shrimp.

 

Figure 11I. A Male Eurycantha sp. From Papua New Guinea.

There are many stick species that exude a noxious odor when disturbed and some species that mimic leaves will sway back and forth as though being windblown. Both of these defensive mechanisms can be readily observed in McCleay's Spectre, an Australian species that is commonly raised by many stick enthusiasts around the world. As with many species of walking sticks, this species exhibits a high degree of sexual dimorphism, with the female looking totally different that the male. In this case the male is less heavy bodied and bears wings (Figure 11J).

 

           

 

                                                                                                      Figure 11J. Right-A female McCleays’s Spectre looking totally different than the male-Left.

 

There is an Australian species of walking stick that is closely related to McCleays’s Spectre that feeds mainly on the plant Casuarina.  The seeds of this plant are small, round and appear very similar to the eggs of the walking stick (Figure 11K).  The plant seeds have a small fleshy part that is highly nutritious and prized by a few species of long-legged ants which readily collect and store them below ground for the winter months.  Due to the similarities in appearances these ants also mistakenly collect and store the walking stick eggs.  However, when the ants begin feeding they recognize that the eggs are of little value and leave them below ground in their nest.  This is obviously advantageous to the walking sticks as the eggs are protected from poor weather and potential predators. Once the sticks hatch the new nymphs are similarly colored and rapidly run around like adult ants.  This allows them to walk out of the ant’s nest unharmed by these predators (the ants).

                          

                       Figure 11K.  Left.  Australian walking stick egg.  Right.  Ant-like walking stick that is very active.

All walking sticks are phytophagous and most will feed on a large variety of host-plants. There is a large walking stick society based in England that has over 700 members throughout the world. Members are primarily amateurs who enjoy raising and studying these delightful insects. The standard plants used to raise most stick species from throughout the world are the leaves of deciduous oak and bramble (blackberry, raspberry etc.). Even though these are not the natural hosts of these insects, most species do quite well on them.

In the United States an USDA permit is required to legally raise or keep walking sticks from foreign countries. The reasoning behind this requirement is that these insects are plant feeders and have quite a wide host range. If some were to get loose, it is possible that they could become pests; consequently, very few permits have been issued in the last few years. Unfortunately, there is a walking stick underground and many people now own colonies of several species. Some pet stores now illegally sell them and the authors have even seen them for sale at a well-known California amusement park. The most commonly reared stick in the United States is Baculun thai (Figure 11L). As with many species, this insect is parthenogenetic. That is, males are not needed to reproduce and only females are reproduced from the unfertilized eggs.

It should be noted that a few exotic species of sticks have escaped from captivity and actually have caused some plant damage in Southern California (mainly San Diego).  However, considering the number of people that are keeping cultures of exotic species of these insects they will probably not cause any major damage to our crops even if escaped.

 

 

                                           Figure 11L. A female Baculum thai, the most commonly raised walking stick  

                                                    in the U.S. Males of this species have not been discovered in nature.

Praying Mantis. These insects are comparatively long-lived, with many species requiring from three to twelve months in the egg stage. After hatching, development to adulthood may range from Three months to two years, with adults living similar periods (depending on the species).

The first name of the mantis is often spelled with either an "e" or an "a." "Preying" refers to the fact that they are predators. "Praying" refers to the behavior of holding their front legs up near their head when hunting. In this case they look as though they are praying. "Praying" mantis is more commonly used than "preying" mantis.

These well-known insects are easily recognized by their elongate prothorax and well-developed raptorial front legs (in raptorial legs the femur is swollen). Since the femur is the bulkiest segment of the leg it houses most of the muscles in the leg.  It follows that mantids would benefit from an enlarged femur to house more muscles and give the front legs additional strength to catch and hold its prey.  Mantids are also well armed with large spines that line the ventral margins of the femur and tibia (Figure 11M). The tibia is also capable of being folded back on the femur forming an efficient grasping organ for their predaceous way of life.

 

Figure 11M.  A common praying mantis with raptorial front legs.

Other characteristics of these beautiful creatures are their huge eyes that help them find prey and the wedge or triangular-shaped head that can rotate in almost any direction (Figure 11N). Mantids are chiefly tropical in origin with over 600 species occurring worldwide. There are only about 20 species in the United States, with most occurring in the southern states.

 

Figure 11N. A common praying mantis with raptorial front leg and huge compound eyes.

 

A few year ago I was reminded how fascinated people are with these amazing insects.  I was in Malaysia working with my friend Michael Yeh (an insect dealer) and he asked me if I wanted a few egg cases of the orchid mantid.   The orchid mantid is a beautiful species that is frequently found on orchid flowers (Figure 11O).  Its coloration blends in perfectly with these flowers. In addition their legs and even abdomen are expanded laterally to blend in with the petals of the orchids on which they frequently sit waiting for a potential prey.  I didn’t think much about it at the time but brought them home.  Once home I forgot about them and most hatched and subsequently died.  I was getting ready for the Cal Poly Insect Fair and found some the mantids with approximate 60 first instar nymphs still living.  I decided to see if anyone would be interested in buying these young so I took them to the fair.  I was amazed how many people wanted to the young at $25 each.  At one point there was a line a dozen or more deep who wanted a baby orchid mantid.

 

 

Figure 11O.  An immature orchid mantid.  Image courtesy of Michael Yeh.

Mantids are general predators, feeding on any insect of appropriate size (neither too small nor too large). As a rule, they are not considered very important in the natural, or biological, control of pest species. Typically, the insect species most important for the biological control of a pest species are those that are host-specific and which feed only on that pest. Because their life cycle is closely tied to that pest, their numbers in the environment will increase as the population of the pest increases and eventually will reduce the pest to a non-problem level. Because mantids are not host-specific, the practice of buying their egg cases in order to turn the hatched nymphs loose for backyard pest control is of little, if any, value.

The praying mantis is cannibalistic, with larger forms commonly eating smaller ones. The female frequently consumes the male after mating. Any male mantid attempting to mate approaches females with great caution (very, very slowly) because he doesn’t want to be eaten before mating. In most cases, he will take several minutes to travel a few inches, especially in her immediate vicinity. Most predators, including female mantids, recognize their prey by movement. In some species, once the male mounts the female and copulation begins, he has a difficult time releasing his sperm packet due to a neurological hang-up located in the brain. However, once the male mounts the female, she reaches backward and bites his head off, thus releasing the neurological block. Then the sperm packet is released and the female consumes the rest of the male.

In the United States, eggs are typically deposited on branches or bark in an egg case or mass, (ootheca) (Figure 11P). This is the overwintering stage. In the spring the young nymphs emerge to grow to adults by late summer or fall.

 

Figure 11P.  An egg case or ootheca of a common preying mantis.

Being large common insects, mantids in many countries are subject to considerable folklore. In Guatemala, children are told that these insects will eat your tongue, if given a chance; consequently, it is not uncommon for children, upon seeing a mantid to slap their hands over their mouths and run as fast as they can. The translation of the Vietnamese name for mantis is heaven’s horse. There it is believed that if you see a mantis, it is considered good luck if you place a drop of honey or sugar on its head as the insect will fly to the heavens and present this gift to the gods. It is no wonder that many people are fascinated by these creatures and there are many myths associated with them considering their interesting behaviors, large size and in some cases, beautiful and striking appearance (Figure 11Q).

 

 

Figure 11Q. An exotic looking praying mantis from Zaire.

 

The coloration and anatomy of many of the mantids blend in with their surrounding environment (Figure 11R).  This could serve two possible functions, namely to protect them from potential predators or hide them from their prey making capture easier.

 

 

Figure 11R.  Four species of mantids with a high degree of mimicry.  Images courtesy of Michael Yeh.

Pet stores occasionally sell praying mantids, with the most common species available being a large green or tan African mantid (Figure 11S). It is best to buy a small nymph, as the adults are not long lived. Mantids can be kept in a small aquarium at room temperature. They will eat almost any insect (adult or immature) of appropriate size (1/4 to 3/4 their size) and should be fed several times a week. Occasionally egg cases can be found in the late fall through spring. In this case, up to 80 or 90 nymphs will hatch in the spring. The young can be kept together if they are provided enough room. When they reach the third instar they will begin to eat one another. Fruit flies are an easily obtained diet for the early instars. Simply let a ripe banana sit for a few days and an instant colony will appear. An alternative source of food for the early instar nymphs is aphids. Mantids do not require a source of water, as they will get enough moisture from their food.

          

 

                    Figure 11S.  A mantis that is commonly available in pet stores and occurs naturally in the US.

 

Crickets. Everyone has enjoyed the peaceful chirping of a cricket on a warm summer night (Figure 11T). And most know that the male produces this chirping to attract the opposite sex for mating. The forewings possess a hardened tooth ("file") and a ribbed ridge ("scraper") on the hindwings. When the wings are rapidly opened and closed, it causes the file to rub over the scraper, thus producing the characteristic chirping.

Actually it is possible to determine the prevailing temperature by counting cricket chirps.  As with all insects, crickets are cold blooded meaning that their body temperature is determined by prevailing temperatures.  And as might be expected the rate of metabolism and activity slows or increases as prevailing temperatures decrease or increase, respectively. As a result, the rate of cricket chirping (number of chirp in a given time) increases or decreases with changes in prevailing temperature. The formula for determining temperature is – count the number of chirps in 15 seconds and add 38.  For example if a cricket chirps 30 times in 15 seconds the prevailing temperature would be 68 F.

An interesting fact, over the past 20 years 90 to 95% of the male field crickets in the Hawaiian Islands have progressively lost their chirp and therefore cannot attract females for mating.  This is apparently due to the process of evolution which in most cases takes hundreds if not thousand of years.  This phenomenon was undoubtedly initiated by genetic mutations in a few individuals of the overall population.  Mutated males lack the scraper and file thus preventing them from chirping.  As amazing as it may seem this loss actually gave these crickets a competitive advantage over those crickets that could sing or chirp.  In the Islands there is a parasitic fly that is attracted to cricket chirping.  Of course these flies then deposit their eggs on the crickets with their larvae subsequently feeding inside and eventually killing them.  The chirp-less crickets do not attract these flies thus the competitive advantage for survival.  At first glance it may seem that since the silent cricket cannot call females this may prevent them from finding a mate and thus reduce their ability to perpetuate their existence.  However they have avoided this disadvantage by merely congregating around the few remaining males that can chirp and thus mating with attracted females.

 

 

Figure 11T. A common field cricket found throughout the United States.

Crickets have historically played a very important role in Chinese folklore, entertainment and recreation. Cricket culture in China encompasses a 2000-year history of insect singing and cricket fighting. The Chinese appreciation of crickets extends far beyond the entertainment value to include their powerful vitality and interesting life cycles. The fact that crickets are capable of laying hundreds of eggs was in line with the historical Chinese beliefs that the one ingredient to a successful life was to have as many children as possible. It was considered a compliment if someone blessed another to have as many children as a cricket. Ground crickets or katydids were even thought to possess aphrodisiac properties.

The keeping of crickets in cages purely for appreciation of their songs became very popular in the Tang dynasty (400 BC). This became popular with both the common people and members of the Royal Palace. In the fall, ladies of the palace would catch crickets and put them in golden cages to appreciate their song during the lonely evening hours. Because most of these ladies were among the 3000 or more concubines of the emperors, their lives were rich in material goods, but lacked social contacts. It is easy to draw similarities between the life of the solitary cricket in a golden cage and the lonely concubines of the palace. Rather than enjoying the sweet chirp of a singing cricket, the concubines may have heard a reflection of their own loneliness and sadness in the cricket chirp.

In some palaces cricket culture was highly refined, with professional cricket "keepers" on the palace payroll. In some cases a mixture of brass powder and rosin was applied with a fine needle to the file-scraper apparatus. This application was said to heighten and refine the volume of the insect's voice.

From the beginning of the Song dynasty (960 to 1278 AD) recreational cricket fighting became very popular in the Chinese culture. At its peak, cricket fighting was as popular with the common people and royalty as profession sports are today in the United States. China even produced the famous Cricket Emperor (Jia Shi-Dao 1213-1275 AD) who was accused of slacking on his duties due to his every encompassing passion of cricket fighting. Thousands of carefully selected crickets were sent to the capital each year, with many a fortune won or lost on the outcome of a single fight. Volumes were written on how to select or selectively breed good fighters.

It is written when a minister of a local rice granary saw a good fighting cricket; he traded a prized horse for it. When he was away on business, his wife took the lid off the cricket pot for a peek at the prize cricket that quickly escaped only to be eaten by a cockatiel (bird). In despair of possible repercussions from her returning husband, the wife committed suicide. Upon his return, the minister seeing his dead wife and lost cricket also committed suicide. It is not known whether he committed suicide over his dead wife or lost cricket.

Anyone who has kept any of a variety of insect-eating pets is well aware of the cost of using crickets for pet food. Generally these can be purchased in a local pet shop or bait store and typically cost around $2.00 per 50 crickets, regardless of size. Of course an alternative to buying crickets is to raise them. This is a fairly easy task with a few minor challenges; the main two are prevention of their escape from the rearing containers and providing the correct environment for egg hatching. Rearing containers should be steep-walled and fairly deep to prevent the later instars and adults from jumping out. Because the hatchlings can climb most surfaces, it is a good idea to coat the upper inside lip of the container with a thin layer of Vaseline. The bottom of the rearing container should be covered with a 1 to 2 inch layer of moist vermiculite, which serves as a substrate for egg laying. The degree of moisture in the vermiculite is critical, as dry or excessively wet conditions will result in death of the eggs. Reaching this ideal level is a matter of experimentation. Start off with fairly moist vermiculite and introduce several adult crickets for about three weeks. After that interval, if small white first instar crickets have not appeared, try again using less moisture until the proper level is determined. Crickets will reproduce and grow at room temperature but when raised at 80 to 85 degrees (F), they will complete one life cycle in about half the room temperature time (three weeks). Water can be provided by a piece of sponge sitting in a dish of water. Crickets eat a variety of foods but chicken mash is a cheap and tidy standby. A cut potato will also provide additional moisture and food.

Jerusalem Crickets. This insect, also called a potato bug, is one of the best known insects in California. Adults are approximately 1 inch long, with a very large, rounded head and a striped abdomen (Figure 11U). As with most Orthoptera, the Jerusalem cricket is a plant feeder. These insects are totally harmless; although, there are many rumors that they are dangerous. These stories are spread in elementary schools and it is a common belief in the Mexican culture that these insects will kill you. The Jerusalem cricket is also known as 'Nino de la Tierra' (Child of the Earth). This name may refer to the somewhat human embryonic look of this ground dweller.

 

 

Figure 11U. A Jerusalem cricket, child of the earth or potato bug.

In Thailand and other Southeast Asian countries a close relative of the Jerusalem cricket is considered a delicacy. In this case the abdomen is split and stuffed with a peanut and subsequently fried. This is another insect that can be easily kept in a terrarium. They do best in a humid environment and will readily feed on most types of vegetables.