This is the largest order containing approximately 40% of all insects.  Assuming there are several million species of insects, this means there are far more species of beetles than there are species of all other plants and animal combined--exclusive of the other insects.  Being such a large order you would expect that there are many medically important beetles.  The opposite is true.  There are relatively few types of beetles that can harm humans.




Some of the really large beetles are capable of biting, pinching and scratching.  Large long horned beetles are capable of delivering at least a very nasty bite when carelessly handled.  I was once collecting in Costa Rica and came across a large specimen of the harlequin beetle.  These beetles have very long legs, an adaptation for living in trees.  It was sitting on top of a short lamppost so I reached up to grab it.  It responded immediately with a nasty bite that drew a considerable amount of blood.  I repositioned my grasp right behind the prothorax.  It then arched its prothorax backward and impaled me with 2 sharp spines on the lateral hind margins of this structure.  As I pulled it off my hand, it raked me with the sharp claws on its long strong legs. (Blood and pain~!) Needless to say this specimen is now on a pin in our entomological museum. 

Other beetles that are capable of delivering pain include some of the very large rhinoceros beetles.  For example, the Asian Atlas beetle has a very sharp ridge in the hind margin of the prothorax and can arch this section backward, easily cutting any flesh as it meets another ridge on the front margin of the metathorax. These beetles are very strong and quite tenacious.  A 5-inch specimen is capable of doing considerable damage as are some of the other large scarabs (see Below)

 Atlas Beetle, Chalcosoma atlas.  This is a species of beetle found in southern Asia, especially Malaysia, remarkable for its size (2 to 6 inches). As common in many insect species, the male is larger than the female and usually two males will fight for a female for mating. The Atlas beetle is, like other beetles of the genus Chalcosoma, notable for its size and the horns. The Atlas beetle differs from other Chalcosoma species (such as C. caucasus) in the end of the cephalic horn of the Atlas, which is broadened.

The larva of the Atlas beetle is known for its fierce behavior, including biting if touched. Unverified reports exist of larvae that live together fighting to the death if there's not enough space or food. In addition the adults can give a nasty bite.  They also have a sharp ridge between the top of the thorax and base of the elytra.  I once caught a rather large specimen and made the mistake of handling it carelessly.  Needless to say it took a hunk out of my finger and in a hurry I grabbed it unfortunately in the ridge area.  It arched it thorax and took another chunk of of my hand.  Of course needless to say in trying to remove it from my now bloody hand it grabbed me with its sharp tarsal claws and strong legs (these guys are very strong) and proceeded to rake my arm as I pulled it off.

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                                                                                                   Larva and Adult of Atlas Beetle.

The origin of the name of the Atlas beetle may be the Greek Titan Atlas or the Atlas Mountains. The fact that the Caucasus mountain range gives its name to another beetle of the same genus (C. caucasus) m

Elephant Beetles, Megasoma elephas.  They are classified with the Neotropical rhinoceros beetles. Elephant beetles are black in color and covered with a coat of fine microscopic hairs. The hairs grow particularly thick on the beetle's elytra. The hairs give the beetle's body a yellowish color. Males have two horns protruding from the head and another from the prothorax. Females have no horns. The horns are used for defense in competition among males for food and mates. In size, Elephant Beetles range between 70-120 mm; males are sometimes even bigger. Males are around 2 to 3 times bigger than the females. Elephant Beetles are located in southern Texas, southern Mexico, Central America, in South American rainforests, and in parts of Australia.

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Elephant Beetle.  Image Courtesy of Derek Ramsey (Ram-Man)


Hercules Beetle (Dynastes hercules).  This is the most famous and largest of the rhinoceros beetles. It is native to the rainforests of Central America, South America, and the Lesser Antilles. Their title is well deserved, with some (exceptionally rare) males reaching 6.75 inches (170 mm) in length. It is the largest of the 6 species in the Dynastes genus, and one of the largest beetles known, being exceeded in length by only two other beetles in the family Cerambycidae, Macrodontia cervicornis (specimens of 170-175 mm are known) and Titanus giganteus (also up to 170-175mm; several seven inch specimens are reputed/alleged to exist). However, if the horns are excluded, this species drops considerably farther down in the size rankings. One reason for this is that the development of the horns is allometric, as well as sexually dimorphic, and thus not strictly correlated to actual body size; it is possible for a female to be much longer, measured from eyes to abdomen, than a male, yet be considered "smaller" simply due to the absence of horns.


                                                                                 Hercules Beetle.  Image Courtesy of Adrian Pingstone

This scarab beetle is most noted for its thoracic and cephalic horns, which can grow longer than the body of the beetle itself. This adaptation is primarily used during fights with other males. Features of this species are the numerous small black spots on the elytra and the thick hairs on the underside of the thoracic horn.

The Hercules beetle is said to be the strongest creature on earth for its size, able to carry 850 times its own body weight.

As noted above, Hercules beetles are highly sexually dimorphic, with the females generally being larger-bodied but much shorter, as they lack horns entirely. The larval stage of the Hercules beetle will last one to two years, with the larva growing up to 4.5 inches (110 mm) in length and weighing up to 120 grams. Much of the life of the larva is spent tunneling through its primary food source of rotting wood. After the larval period, transformation into a pupa, and molting, the beetle then emerges as an adult. Adults will roam the forest floor in search of decaying fruit.

Of course some of the largest beetles (especially in the longhorned beetle family) are capable of delivering a painful bite.  Titan beetle (Titanus giganteus) is the largest known beetle in the Amazon rainforest and one of the largest (if not largest) insect species in the world. The titan beetle is the only member of its own genus. It is known from the rain forests of Venezuela, Colombia, Ecuador, Peru, the Guianas, and north-central Brazil, where it is most commonly collected by the use of mercury-vapor lamps, to which the males are attracted. There is a local 'cottage industry' in French Guiana of leading tours specifically to collect specimens of this beetle (which can command prices over US$500), and other countries' ecotourism agencies mention these beetles in their advertisements.

Adults can grow up to 6.5 inches in length. It is said that their mandibles can snap pencils in half and cut into human flesh. Adult titan beetles do not feed; they simply fly around to find mates. They are attracted to bright lights after dark. There is an extensive sequence towards the end of Sir David Attenborough's Life in the Undergrowth series (in the version released in the UK) which prominently features a hunt for this beetle. In it, an adult specimen was found and brought back to Oxford University. Because the adults do not eat, this specimen was cared for until it died.


                                                                                Titan Beetle.  Largest Beetle in World.  Image Courtesy of Karmesinkoenig

The larvae have never been found, but are thought to feed inside wood and may take several years to reach full size before they pupate. Boreholes thought to be created by titan beetle larvae seem to fit a grub over two inches wide and perhaps as much as one foot long. A famous "life-size" photograph of a putative larva of this beetle appeared in National Geographic Magazine, filling an entire page, but it was of a different species of beetle, possibly Macrodontia cervicornis. The adults defend themselves by hissing in warning, and have sharp spines as well as strong jaws.

Macrodontia cervicornis.  This is the largest and best-known member of this genus of long-horned beetles. This species is sometimes considered the second longest among all beetles, with known specimens exceeding 7 inches in length. A fair bit of this length, however, is due to the enormous mandibles, from which it derives both of the names in its name Macrodontia means "large tooth", and cervicornis means "deer antler". For that reason, it is generally excluded from consideration by purists who do not take the jaws, legs, or antennae of a beetle into account when determining length. It is very attractive to insect collectors and can be priced at up to $500.This species is known from the rain forests of Colombia, Ecuador, Peru, Bolivia, the Guianas, and Brazil. Additional described species in the genus extend the overall range of the genus from Guatemala to Argentina.

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                                                                                                  Macrodontia cervicornis-One of the World’s Largest Beetles.



                                                                                                                                           BLISTER BEETLES


This is a rather small family in term of number of species but quite large in terms of the size of the individual insects.  Most meloids are ¾ inches or larger, soft body with a narrow neck and deflexed head.  The soft bodied characteristic refers to flexible elytra. With most beetles the elytra is hard and inflexible.




 Typical blister beetles illustrating deflexed head, narrow thorax and elongated body.  Left image courtesy of Clemson University Entomology.

Blister beetles are so called for their defensive secretion of a blistering agent, cantharidin. There are approximately 7,500 known species worldwide. Many are conspicuous and some aposematically (warning coloration) colored, announcing their toxicity to would-be predatorsCantharidin is a poisonous chemical causing blistering of the skin. It is used medically to remove warts and is collected for this purpose from species of the genera Mylabris and Lytta, especially Lytta vesicatoria, better known as "Spanish fly".  The Spanish fly contains up to 5% cantharidin which irritates animal tissues. The crushed powder of Spanish fly is of yellowish brown to brown-olive color with iridescent reflections, of disagreeable scent and bitter flavor.


The Spanish Fly Beetle.  Image courtesy of œuvre personnelle.

Spanish Fly-Lytta vesicatoria. Other species of blister beetle used by apothecaries are often called by the same name. Lytta vesicatoria is sometimes incorrectly called Cantharis vesicatoria, but the genus Cantharis is in an unrelated family, Cantharidae. The beetle contains up to 5% cantharidin which irritates animal tissues. The crushed powder of Spanish fly is of yellowish brown to brown-olive color with iridescent reflections, of disagreeable scent and bitter flavor.

Spanish fly, or cantharides as it is sometimes called, is often given to farm animals to incite them to mate. The cantharides excreted in the urine irritate the urethral passages, causing inflammation in the genitals and subsequent priapism (sustained erection). For this reason, Spanish fly has been given to humans for purposes of seduction; they help men keep a longer erection. It is dangerous since the amount required is minuscule and the difference between the effective dose and the harmful dose is quite narrow. Cantharides cause painful urination, fever, and sometimes bloody discharge. They can cause permanent damage to the kidneys and genitals.

Adults feed on leaves of ash, lilac, amur privet, and white willow trees; larvae are parasitic on the brood of ground nesting bees. These beetles lives in scrublands and woods throughout southern Europe and eastward to Central Asia and Siberia.

Medical use of this chemical dates back to descriptions from Hippocrates. Plasters made from wings of these beetles have been used to raise blisters. In ancient China, cantharides beetles were mixed with human excrement, arsenic and wolfsbane to make the world's first recorded stink bomb.

It is also one of the world’s most well-known aphrodisiacs:

§         In Roman times, Livia, the scheming wife of Augustus Caesar, slipped it into food hoping to inspire her guests to some indiscretion with which she could later blackmail them.[5]

§         Henry IV (1050–1106) is known to have consumed Spanish fly at the risk of his health.

§         In 1572, Ambroise Paré wrote an account of a man suffering from "the most frightful satyriasis" after taking a potion composed of nettles and cantharides.[6]

§         In the 1670s, Spanish fly was mixed with dried moles and bat's blood for a love charm made by the magician La Voisin.

§         It was slipped into the food of Louis XIV to secure the king's lust for Madame de Montespan.

§         In the 18th century, cantharides became fashionable, known as pastilles Richelieu in France.

§         The Marquis de Sade is claimed to have given aniseed-flavored pastilles that were laced with Spanish fly to prostitutes at an orgy in 1772. He was sentenced to death for poisoning and sodomy, but later reprieved on appeal.

In Medicine & Podiatry, it is used as a topical application for treatment of benign epithelial growths including most warts.

In powder, mixed with the food, cantharide could go unnoticed. Aqua toffana, or aquetta di Napoli, was one of the poisons associated with the Medicis. Thought to be a mixture of arsenic and cantharides, it was reportedly created by an Italian countess, Toffana. Four to six drops of this poison in water or wine was enough to deliver death in a few hours.

In order to determine if a death had taken place by the effects of Spanish fly, investigators resorted to the vesicación test. One of those test methods consisted of rubbing part of the internal organs of the deceased, dissolved in oil, on the shaved skin of a rabbit; the absorption of the cantharides and its blistering effect are such that they became visible on the skin of the rabbit.

Cantharides are illegal in the United States, except for use in animal husbandry and by licensed physicians for the topical treatment of certain types of warts. Some Internet or mail order suppliers of sex stimulants advertise such products like "Herbal Spanish fly", "Mexican Spanish Fly", or "Spanish Fly Potion". Most of these products are simply cayenne pepper in capsules, sometimes blended with the powder of ginseng, kelp, ginger or gotu kola.  The products with the name "Spanische Fliege (Spanish fly)" that are available in Germany represent no danger since they are diluted to the point where they contain no trace of the active substance, as they are homeopathic remedies.

Blister beetles are both destructive and beneficial.  In most cases the adults are phytophagus feeding on a variety of crops including legumes, beets, potatoes, ornamental flowers, tomatoes and others.  The larval stages, depending on the species, are predatory mainly on either grasshopper egg pods in the soil or attack the young of wild bees.  Some consider them as parasitoids but they exhibit characteristics of both predators and parasitoids.


Lytta magister (also known as the desert blister beetle or master blister beetle) is a species of blister beetle found in southwestern North America. Typically 16 to 33 mm (0.6 to 1.3 in) in length, L. magister has a striking red head, legs and prothorax, with black elytra. They can be found in great numbers in the Mojave and Colorado Deserts in spring, and are often seen in swarms.[1] Females lay eggs in holes in the desert soil. The larvae are insectivorous, mainly attacking bee nests.  They consume the immature host along with its provisions, and can often survive on the provisions alone, thus they are not obligatory parasitoids but rather food parasites that are facultatively parasitoid, or simply predatory. Adults feed on flowers and leaves of brittlebush.

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                                                                                         Desert Blister Beetle.  Image Courtesy of Rockpocket.

These insect exhibits hypermetamorphosis, a type of complete metamorphosis.  In the case of hypermetamorphosis the larval stage not only increases in size, but unlike insects with standard complete metamorphosis, it changes form with progressive molts.  These changes are associated with their mode of life.  The first instar larva is called a triungulin and is silver fish-like in appearance.  This form actively seeks out grasshopper egg pods in the soil or in the case of those forms that feed on wild bees may sit and wait on flower heads for these pollinators.  In the latter cases, once available it attaches to the bee’s hair and is carried back to the nest.  Once reaching the nest or egg pod the larvae become more grub-like and eventually legless with progressive molts-at this point all the food necessary for development is provided and legs are no longer needed.  Those forms that feed on egg pods are quite beneficial in controlling these pests.  One larva is capable of consuming a whole pod (30 eggs) during its development.  Those forms that feed on wild bee larvae could be considered destructive because the insects are valuable pollinators.



                                                                                                              STAPHYLINIDAE-ROVE BEETLES.


The rove beetles are a large family (Staphylinidae) of beetles, primarily distinguished by their short elytra that leave more than half of their abdomens exposed. With over 46,000 species in thousands of genera, the group is the second largest family of beetles after the Curculionidae (the true weevils).  As might be expected for such a large family, there is considerable variation among the species. Sizes range from 1 to 35 mm (1.5 inches), with most in the 2-8 mm range, and the form is generally elongate, with some rove beetles being ovoid in shape. Colors range from yellow to reddish-brown to brown to black.


 Most are small with a parallel-sided body and exhibit the behavioral characteristic of turning the tip of their abdomen upward when disturbed. In the majority of these insects, the larvae and adults are predatory and a few are parasitic.  These are very common insects and undoubtedly play a more important role in the biological control of pests. Common habitats include decaying vegetation, leaf litter, fungi, compost piles and around decaying carcasses.


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                                                                                                     Nairobi fly or Kenya Fly.  Image Courtesy of (

Nairobi fly-Paederus. This species contains a potent toxin in its haemolymph which is highly irritating to the skin. Pederin is highly toxic, more potent than cobra venom.  The name Nairobi fly or Kenya Fly is applied to two species of beetle which live in East Africa, Paederus crebinpunctatus and Paederus sabaeus. They are black and red in color, and about 6–10 mm long. They live in rotting leaves where they lay their eggs. The beetles neither sting nor bite, but their haemolymph contains pederin, a potent toxin which causes blistering. The toxin is released when the beetle is crushed against the skin. People are advised to brush or blow the insect off their skin to prevent irritation. Paederus fuscipes is probably the major agent that causes linear dermatitis in northern Iran. Whereas this disease is a rural difficulty in the south, mainly in villages or small towns, it is an urban problem in Northern provinces along the Caspian Sea shore. Heavy rains, sometimes brought on by El Niño events, provide the conditions for the Nairobi fly to thrive. Correspondingly outbreaks have occurred in 1998 and 2007.

Dermatitis Caused by Nairobi Fl

                                                                                                                                         BEETLE FRASS


There are a number of beetles, both as larvae and adults, which bore into and feed internally in cut bamboo.  These do not normally cause much concern in the United States, but in Asia, Africa and other tropical areas of the world where bamboo is one of main building materials in homes, it can be of considerable concern.  This is especially true where bamboo is used for constructing roofs.  As the bamboo dries, beetle infestations can become quite heavy and as these insects cut bamboo and feed, their frass (feces) and bamboo fibers are forced out and filter down onto the inhabitants.  Once on the skin, these materials can cause a severe rash that has to be treated medically. Considering that the Asian and African population represents a high percentage of the people in the world and how commonly bamboo is used in home construction, this may be one of the most common, although not most serious human ailments associated with insects.




The adult moth represents essentially no medical threat to humans; however, there are some species of caterpillars that have urticating or stinging hairs covering their bodies.  Skin contact with these hairs, which are hollow and contain a poison, results in a stinging sensation.  These hairs can produce a reaction long after the death of the caterpillar.  Worldwide there are many species of caterpillars with urticating hairs.  Most of these are brightly marked (Figure 64) with warning colorations advertising the fact that they should be left alone.  Common documented species that possess urticating hairs include the saddleback moth, slug caterpillar, flannel moth and io moth.  Worldwide the list is quite sizable.


I was once walking along a dirt road in Thailand and came across a bush with several saddleback caterpillars.  I knew they had urticating hairs but I decided to touch them in order to experience what the result would be.  The sting was more severe than I had expected.  It almost felt like a severe electric shock had run through my hand.  That evening we were driving up a mountain looking for giant millipedes crossing the road.  After catching several we stopped for another only to find out that it was a giant caterpillar about 6 inches long.  Without stopping to think that this caterpillar looked quite hairy, I picked it up, resulting in the same response as the saddleback but about twice as bad.




An unknown species of Thai caterpillar with urticating hairs.



Well Known Species

Saddleback Caterpillar.  The saddleback caterpillar, Sibine stimulea, is the larva of a species of moth native to eastern North America. The species belongs to the family of slug caterpillars, Limacodidae. It is also known as the "packsaddle".

The caterpillars are primarily green with brown at either end, and a prominent, white-ringed brown dot in the center which resembles a saddle, hence the name. They feed on a large variety of plants, and the adults are dark brown, stout-bodied moths. In Florida, they are known to feed on ornamental palms such as the Adonidia merrilli (Christmas palm).

.Stings can be very painful. They can cause swelling, nausea, and leave a rash that can last for days. Individuals with sensitive skin are cautioned against coming into contact with them as the reaction can be more severe than the typical reaction. The primary nettling hairs are borne on the back of paired fleshy protuberances toward the front and hind ends of the body. There is also a row of smaller stinging organs on each side. This caterpillar feeds on many plants, including hibiscus and palms, but appears to show little host preference.




Hag Moth.  The larva is distinctive, with no close analogues although it may be mistaken for the shed skin of a hairy spider or leaf debris. It has six pairs of curly projections, three long and three short from the flattened body, each densely covered in hairs. According to David L. Wagner, who experimented on himself, the hairs do not sting, contrary to popular belief. However, susceptibility can vary among humans and it may produce a reaction in some people. Some members of the family Limacodidae do sting. Like all Limacodids, the legs are shortened and the prolegs are reduced to suction cups. The 'arms' can fall off without harming the caterpillar.   Maximum length of larvae, 2.5 cm.  It is solitary and is not a very significant agricultural threat, but it is a common sight in orchards.

                       The adult moth has a wingspan of up to 3 cm. The male has translucent wings, and the female is drab brown and gray, with yellow puffs on her legs. The day-flying     

                  female is said to mimic a bee, complete with pollen sacs, and the male mimics a wasp.

Eats a variety of deciduous trees and shrubs, not limited to: apple, ash, birch, cherry, chestnut, dogwood, hickory, oak, persimmon, walnut, willow.




Puss Caterpillar. It is a convex, stout-bodied larva, almost 1" long when mature, and completely covered with gray to brown hairs. Under the soft hairs are stiff spines that are attached to poison glands. When touched, these poisonous spines break off in the skin and cause severe pain. Puss caterpillars feed on a variety of broadleaf trees and shrubs, and are most often found on oaks and citrus. In Florida there are two generations a year, one in spring and the other in fall. Natural enemies keep these caterpillars at low numbers during most years, but they periodically become numerous.




Io Moth.  Larvae are about 2 to 2-1/2 inches long full-grown, pale-green with a narrow, reddish stripe edged underneath with white that extends lengthwise along each side of the body. It appears spiny (numerous clusters of urticating hairs). Each body segment is equipped with several fleshy tubercles armed with numerous long, greenish venomous spines tipped with black. Pain is less severe than the puss caterpillar.


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                                                                                       Image Courtesy Michael Holryod


46.                       Comparatively very few beetles are considered dangerous although some of the larger species can inflict a painful bite.

47.                       Blister beetles excrete cantharadin and as the beetle’s name implies this acid when in contact with the skin can cause blistering.

48.                        Another name for cantharadin is Spanish fly, a so-called human aphrodisiac.

49.                       Urticating hairs are commonly found on brightly colored caterpillars in tropical countries of the world.