An online resource based on the award-winning nature guide

Hymenoptera

Braconid Wasps Pupating and Emerging

8-29-14 braconid wasps 010Tobacco Hornworms, Manduca sexta (often found feeding on tomato plants and confused with Tomato Hornworms, Manduca quinquemaculata) are often the target of a species of a Braconid wasp (Cotesia congregata) that parasitizes beetle, moth, fly and sawfly larvae. The adult wasp lays her eggs inside the hornworm with her long ovipositor. The eggs hatch and the wasp larvae feed on the caterpillar. Eventually the wasp larvae emerge and spin silk pupa cases (cocoons) on the skin of the dying hornworm caterpillar, inside of which they transform into winged adults within four to eight days. Braconid wasps are extremely good at locating hornworms, even when there are very few to find. Because they parasitize hornworm, cabbage worm, aphid and gypsy moth larvae, Braconid wasps are considered important biological control agents. If you want to discourage Tobacco Hornworms in your tomato patch, allow the wasps to complete their metamorphosis – this accomplishes both the demise of the hornworm, as well as an increased population of Braconid wasps. (Thanks to Emily and Joe Silver for photo op.)

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Great Golden Digger Wasps Digging Nests & Provisioning Them with Food

8-11-15 great golden d.w.2 159The Great Golden Digger Wasp, Sphex ichneumoneus, is a solitary, predatory wasp whose hunting and nesting techniques are programmed and never vary. Having overwintered underground in a nest dug by its mother, the adult wasp emerges, often in August, and begins preparations for the next generation. She digs several nests in packed, sandy soil, using her mandibles to cut the earth. Emerging backwards from the ground with a lump of soil between her forelegs and head, she flips the soil with her forelegs beneath her body, scattering it to the sides with her hind legs. In this manner she excavates several cells off a central 4-6-inch deep tunnel.

The wasp seeks out prey — often a grasshopper, cicada or cricket – and then stings and paralyzes it. If the prey is small, she flies it directly to the nest. If prey is too large to transport aerially, the wasp will walk with it across the ground, dragging it by its antennae (see photo). She then drops the prey several inches from the nest hole. After crawling down into the nest for a brief inspection, she pulls the prey down into one of the cells while walking backwards. She then leaves to find another insect. When a cell contains paralyzed prey, the wasp lays an egg on the insect. The egg hatches within two or three days and the wasp larva begins eating the insect. Because the prey is not dead, decomposition is delayed, and the wasp larva’s food is relatively fresh. The developing wasps overwinter in the nest and emerge the following summer to begin the process all over again.

If you live near a sunny area of compacted clay and sand that has flower nectar for adults to feed on and crickets, grasshoppers and katydids for their larvae, you may well have a chance to observe this unique ritual. (Thanks to Marian Cawley for photo op.)

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Unequal Cellophane Bees

5-12-14  cellophane bee  205Ninety percent of bees are solitary – the fertile females create their own cells and feed their own young, with no help from a colony of worker bees. They often nest underground, rarely sting and are excellent pollinators, even though they don’t store honey. Colletes inaequalis, a type of Plasterer Bee also known as the “Polyester Bee,” and “Unequal Cellophane Bee,” is a solitary bee. It derives its common names from the practice of lining its underground nest cells with a secretion that, when it dries, forms a smooth, cellophane/polyester-like lining. This cell holds one egg suspended above a collection of pollen and nectar on which the larva will feed. The Unequal Cellophane Bee is crepuscular, which can be deduced by the large size of its eyes. It is one of the earliest species to become active in the spring, sometime between March and May, when adults bees emerge from underground chambers off a vertical tunnel dug by their mother last spring. (Why it is called an “Unequal” Cellophane Bee I have not been able to determine.)

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Basking Bumblebees

10-10-13  basking bumblebee 016Bumblebees are some of the earliest bees to emerge in the spring and are often the last to be seen in the fall. They can regulate their own body temperature by shivering or basking in the sun. This enables bumblebees not only to stay active longer during the season, but also during wet or cooler weather. Look for them on sunny patches of ground at this time of year.

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Pelecinid Wasps Laying Eggs

9-11-13 pelecinid wasp 211The two-inch, skinny, black, shiny wasps with extremely long abdomens (five times the length of their bodies) that have been appearing on lawns lately are not the villains you may think. These female Pelecinid Wasps (males are much smaller and rarely seen) are actually beneficial, in that they greatly decrease the June Bug population. That long abdomen, or ovipositor, cannot sting you – it is strictly a mechanism for laying eggs. Its length is due to the fact that the wasp inserts its ovipositor deep into the ground in order to locate beetle larvae — specifically, June Bug beetle larvae. The wasp then lays one egg on each host beetle larva, and when the egg hatches, the wasp larva burrows into the host as it feeds on it, thereby killing the June Bug beetle larva. Eventually the wasp larva pupates and emerges above ground as an adult wasp the following summer – the phenomenon we are currently witnessing.

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Bottle Gentian Flowering

9-10-13 bottle gentian IMG_8093Bottle Gentian, Gentiana andrewsii, is one of our latest blooming wildflowers, and one of our most beautiful. Because its petals are closed so tightly, only bumblebees (pictured) and a few other insects have the strength to push their way inside the flower to reach Bottle Gentian’s sugar-laden nectar.

Like many other flowers, Bottle Gentian times the maturation of its reproductive parts to discourage self-pollination. Male pollen-bearing stamens mature first, and by the time the female pistil is mature, the stamens have gone by so the flower’s pistil can’t receive its own pollen (see central pistil surrounded by withered stamens in insert).

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Cerceris fumipennis: a biosurveillance tool for the emerald ash borer

8-19-13 Cerceris wasp with beetle prey2 099While we’re more familiar with social wasps, such as paper wasps, yellow jackets and hornets, there are also parasitic and solitary wasps. Solitary wasps live alone (as their name implies), all the females (not just the queen) are fertile and they are predatory. Among them is a wasp, Cerceris fumipennis, which preys exclusively on the family of beetles (Buprestidae) to which the Emerald Ash Borer (EAB), the invasive beetle that’s threatening the ash tree population, belongs. After catching and paralyzing its prey, the wasp carries it back to her larvae in the nest she’s dug underground. A biosurveillance program exists which involves monitoring the prey that this species of wasp collects and brings back to the nest, in order to detect the presence of the Emerald Ash Borer in any given area. (This is how the EAB was first detected in Connecticut.) Pictured is a Cerceris fumipennis wasp with a Buprestid beetle (not an EAB) prey. (To become involved in Vermont’s citizen science biosurveillance program next summer, contact entomologist Trish Hanson of the Vermont Dept. of Forests, Parks and Recreation at Hanson.Trish@state.vt.us .)

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