Deathwatch Beetle

This week's insect images depict a beetle that my neighbor found in her chamomile tea. It belongs to the family Anobiidae which contains a number of pests of stored products, including timber, cereal, tobacco and chili powder. Some species are called deathwatch beetles because they could be heard chewing through wooden coffins during the silence of a wake.

If you happen to find one of these tiny insects in your tea, there is probably no need to throw it out. A panel of unbiased judges unanimously found the infested tea to "taste fine"!

Phytophagy

Dear Recipients,

This week features two types of beetle that feed on plant (phytophagy). The first belongs to the family Chrysomelidae, which contains species that feed chiefly on foliage and flowers. This group contains many pest species such as the Colorado Potato Beetle and Flea Beetles. The second beetle is a weevil (Curculionidae) which also contains may pest species. However, unlike most chrysomelid larvae, weevil larvae typically burrow into the host plant or seed on which they are feeding. As can be seen in this specimen, most weevils have the mouthparts and antennae at the end of a snout.

Elijah

Chlorion

Hello Recipients,

The solitary wasp featured this week belongs to the genus Chlorion (Hymenoptera: Sphecidae) and was collected by a local insect enthusiast. This wasp makes its nest in loose or sandy soil which it provisions with crickets or cockroaches that it paralyzes with its sting. These paralyzed prey items provide food for the wasp larvae. The adult wasps feed on nectar and hunt only for their offspring.

The white arrow in the photo of the full wasp indicates the location of the wasp's propodeal spiracle. As many of you may know, insects breathe through holes in their bodies (spiracles) that allow diffusion of oxygen from the air into the insect's blood. The close up image illustrates the external structure of the spiracle as well as the beautiful color and sculpture of the wasp's exoskeleton.

Hoplocrepis

This week features a rather strange looking parasitic wasp from Brazil. It belongs in the genus Hoplocrepis (Chalcidoidea:Eulophidae), a group whose biology remains unknown.

Lace Bug

This week features a lace bug (Hemiptera: Tingidae). These rather common plant feeders are typically only as ornate you see here during the adult stage, the nymphs are usually spiny. Most species in North America feed on herbaceous plants but some feed on trees and may cause considerable damage through loss of foliage.

Horse Fly

Behold the face that bites you!

By special request this week's image is the face of a horsefly (Diptera: Tabanidae: Tabanus). The males feed primarily on nectar and pollen but the females thirst for blood to nourish the development of their eggs. Horseflies and their close relatives, the deerflies, can become a serious nuisance and in the United States they are known to have spread the bacterial diseases anthrax and tularemia.

Cuckoo Wasp

This week's image is dedicated to the person who recently stated that "wasps just aren't that colorful". This shiny little creature is a cuckoo wasp in the family Chrysididae. These insects are common on flowers and are harmless to humans. Most parasitize the full grown larvae of bees or other wasps, some attack the larvae of sawflies and the eggs of walking sticks.

Grasshopper

This week features a familiar insect- the grasshopper. This particular specimen came from the Lost Coast in northern California and belongs to a group known as spur-throated grasshoppers (Cyrtacanthacridinae).

If you look between the bases of the front legs you will see the spur for which these grashoppers are named. This structure is easily visible with the naked eye, especially in large grashoppers, allowing you to impress your friends and neighbors with your identification skills the next time you catch one of these!

Eulophidae

This week features two species of parasitic wasp developing on the same host; this phenomenon is known as superparasitism. Both of the parasitic wasps belong to the family Eulophidae (Chalcidoidea), which often feed on their hosts externally as illustrated by the larvae on the outside of the caterpillar. These wasps also pupated outside of the host. In this case they pupated on a leaf. If you look closely you can see the form of the pupae in the pupal skin left behind.

Superparasitism creates a competitive environment between species. In some polyembryonic species (in which one egg produces many clonal indiviudals), a few clones do not develop into adulthood. They instead become "cruisers" that seek out competing parasitic species and kill them for the benefit of their sibling clones.



Photo of caterpillar by Joshua Benoit.
All specimens collected by Joshua Benoit

Hispinae

This week's image features a beetle in the subfamily Hispinae (Chrysomelidae) from Slovakia. This larvae of these beetles mostly feed on the inside of leaves and occasionally become agricultural pests.

Inostemma

This week brings a parasitic wasp from the grassy fields of Hungary. It is a species of Inostemma (Platygastridae), a genus in which females typically have the distinctive "horn" seen extending from the abdomen over the thorax. This structure houses an ovipositor (syringe-like egg laying apparatus) longer than the body itself. It uses this ovipositor to insert its eggs into the larvae of hard-to-reach gall midges (Cecidomyiidae).

Microgastrinae

This week's image is a response to a question about a caterpillar with cocoons on its exterior. One such caterpillar was found by Zuzana Muranicova in the tomato plants in front of our home this summer. As her photograph illustrates, hundreds of tiny cocoons hang from the exterior of the caterpillar as parasitic wasps consume it. This type of external parasitization is common among the culprit, a microgastrine braconid wasp (Hymenoptera: Ichneumonoidea: Braconidae:Microgastrinae). Species in the genus Cotesia belong to this group and have been used extensively as biological control agents against caterpillars. The wasp image is of a microgastrine wasp which I collected in front of my home later in the summer, maybe it is one of the hatchlings!!!

Plutomerus

This week's insect image is of a parasitic wasp in the genus Plutomerus. Less than 10 specimens are known to exist; this one was recently collected in Indonesia. The first segment of the antenna forms a shield into which the remaining segments can fit. Nothing about its life history is known.

Propodeum

The following images illustrate a region of wasps call the propodeum which is between the thorax and the remainder of the abdomen (the propodeum is ancestrally an abdominal segment). These two specimens are parasitic wasps from Brazil in the subfamily Diporinae (Chalcidoidea: Pteromalidae). Little is known about their biology and they are suspected to parasitize the beetle larvae.

Podagrion

Behold the elegant beauty of Podagrion (Chalcidoidea: Torymidae)!!!

This tiny wasp comes from Brazil where it parasitizes the eggs of praying mantises.

Anopheles gambiae

By special request, this week's image is a comparison of male and female heads of the mosquito Anopheles gambiae (Diptera: Culicidae). The male is on the left and the female on the right. An interesting behavior in some mosquito species is that the females respond to specific range of sound frequency produced by the wings of the males. Smaller males (with smaller wings) beat their wings more slowly to decrease the frequency of sound that they produce and thus give an audio illusion of larger size.

Perilampidae

The attached image is of a parasitic wasp in the family Perilampidae (Chalcidoidea) collected at Bradford's Pond in Franklin, NH. Typically, these wasps lay their eggs on vegetation which then hatch into small flat larvae. These larvae will only develop after being eaten by a caterpillar that is parasitized by another insect, such as a parasitoid fly. The perilampid larvae will then attack the other parasitoid- hence they are called hyperparasitoids.

Happy Halloween and be glad that you are not small,

Heptascelio dispar

This week's image is of a Botswanan species in the genus Heptascelio. This genus is found throughout Africa, and Southern Asia. A few species are known to attack the eggs of grasshoppers. If you would like to know more about this genus, the following link will provide access to a recent revision.

http://www.mapress.com/zootaxa/2008/f/zt01776p051.pdf

Photograph by Norman F. Johnson

Ensign Wasp

If you are someone who lives in squalor, or in New York City, you may notice small black insects flying around the insides of your windows. If so, they might be ensign wasps (Evaniidae) like the one in this week's image. These wasps attack the egg cases, or oothecae, of cockroaches. The wasp larvae eats all of the cockroach eggs and they are thus considered to be predators and not parasitoids. This particular specimen was collected in my backyard near dumpsters which support a population of the Oriental cockroach (Blatta orientalis). Fortunately, this species of cockroach does not invade houses.

Piestopleura

This week's image is of a parasitic wasp in the genus Piestopleura. As a member of the subfamily Platygastrinae, it parasitizes the eggs or larvae of small flies (Cecidomyiidae) that form galls in plant tissue. The wasp egg does not hatch until the fly larvae is full grown, at which point it develops rapidly and consumes its host. In cases where the host is much larger than the wasp, the egg will divide many times resulting in identical clones that allow many wasps to form from a single egg. This is known as polyembryony.

Sparasion

This week's image fulfills a special request for a blue insect, something not uncommon among parastoid wasps. This very large specimen comes from Borneo and belongs to the genus Sparasion which can also be found in Eurasia, Africa, and temperate North America. Host records indicate that these wasps are parasitoids of katydids (Orthoptera: Tettigoniidae). Sparasion and 4 other genera form a tribe called the Sparasionini and display many ancient, or plesiomorphic, characters. If you would like to read more about this tribe, the following link to a recent paper is provided.

http://128.146.250.117/pdfs/21835/21835.pdf

Assassin Bug

By special request, this week's image is of an assassin bug (Heteroptera: Reduviidae). These common insects are usually predatory and often use their powerful forelegs to catch prey. The innards are then sucked out with a proboscis that is held at rest underneath the bug's body. The base of it can be seen on the underside of the head in this specimen. A few species in this family are blood feeding, and the pathogenic trypanosome that causes the incurable Chaga's disease is spread by one such insect, the Blood Sucking Conenose (Rhodnius prolixus). This species has also been used extensively to study molting and the physiology of insects.

Happy Weekend!

Lady Bug

By special request this week's image is of a ladybug, or ladybird beetle (Coleoptera:Coccinellidae). Almost all species of these insects are beneficial because the larvae and adults feed on pests such as aphids or scale insects.

Formicidae

By long time request this week's image features an ant (Hymenoptera: Formicidae). Agriculture, slavery and social division of labor were employed by ants long before the existence of humans. Some have estimated that the biomass of ants roughly equals that of humans. Ants have a node (or two) on the constricted segment of the abdomen (see arrow) and this character identifies them from other flightless wasps. Tomes of literature are available on these ever working insects so I will leave further inquiry to you.

Trichacoides

Due to current construction in the OSU Insect Collection I am temporarily unable to fulfill special requests. Consequently, you now receive a jewel from the Orient, Trichacoides (Hymenoptera: Platygastridae: Platygastrinae). If you ever are fortunate enough to sort the contents of insect traps from Southeast Asia you will probably find many of these tiny wasps. This genus is easily identified by the spines covering its mesoscutellum (see close up image).

The general life history of the Platygastrinae was previously stated in the Piestopleura edition of Insect Image of the Week but it is here repeated for new recipients and those of you who may have forgotten.

Members of the subfamily Platygastrinae parasitize the eggs or larvae of small flies (Cecidomyiidae) that form galls in plant tissue. The wasp egg does not hatch until the fly larvae is full grown, at which point it develops rapidly and consumes its host. In cases where the host is much larger than the wasp, the egg will divide many times resulting in identical clones that allow many wasps to form from a single egg. This is known as polyembryony.

Echthrodesis lamorali

This week's image is of Echthrodesis lamorali (Hymenoptera:Platygastridae). This parasitoid wasp is known only from the shore of the Cape Peninsula in South Africa. Here it parasitizes the eggs of a spider, Desis formidabilis (Araneae: Amaurobiidae), in the intertidal zone.

Hippoboscidae

This week features a kind of fly often referred to as a ked (Family=Hippoboscidae). The flattened body form and powerful legs help this fly grab onto mammals on whose blood it feeds. This specimen was collected at the edge of a field in the hills of Slovakia where sheep and goats frequently graze, little do they know that they are the site of grazing themselves!