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Insects

Dog-day Cicadas Emerging, Courting, Mating and Laying Eggs

8-24-16 mating cicadas by wallie hammer IMG_2199

Adult annual cicadas, including the pictured Dog-day Cicadas, have emerged from their subterranean dwellings. High up in trees most males are vibrating their abdominal tymbals (drum-like organs) in order to woo female cicadas with their “song.” Thanks to an abdomen that is relatively hollow, the sound is intensified, and very audible to human ears as a high-pitched whining drone, somewhat resembling a buzz saw. We associate it with the hot, humid “dog days” of July and August.

Annual cicadas emerge from the ground (where they have been feeding off of the sap of trees through the trees’ roots for two to four years) every year as nymphs. They climb a tree, split and emerge from their exoskeleton, or outer skin, and pump their wings full of fluid. After their exoskeleton dries, the adult cicadas (also called imagoes) head for the canopy, and males commence “singing” to attract a mate. Within two weeks mating takes place, eggs are laid in slits of live branches and the adults die. After hatching, the nymphs will drop to the ground and burrow into it with their shovel-like front legs. (Thanks to Wallie Hammer for taking and providing today’s photograph. Mating usually takes place in the canopy, and therefore rarely seen.)

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Eggs Of Migrating Generation Of Monarchs Hatching

7-19-12 monarch eating eggshell IMG_4494

The Monarch eggs that are hatching now contain the larvae that will metamorphose into the butterflies that will migrate this fall to central Mexico. Unlike earlier-hatching generations that only live six to eight weeks, the Monarchs that result from late summer and early fall hatchings live six to nine months. Part of the reason for this difference in life span is that, unlike the earlier generations that mate soon after emerging from their chrysalides, late-hatching Monarchs postpone mating (reproductive diapause) until the end of winter, thereby conserving energy for their two to three thousand-mile, two-month migration. (Photo: monarch larva’s first meal – its eggshell.)

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Female Black and Yellow Mud Dauber Wasps Making Cells & Laying Eggs

8-19-16  mud dauber 028If you look closely at the ground directly in front of this female Black and Yellow Mud Dauber wasp you will see the clump of mud that she has collected and rolled into a ball with her mandibles.  This lump of mud will be carried back to the nest site in the wasp’s mandibles, and then used as building material to mold a cell.  After making the mud cell, the wasp then goes and locates spiders, stings them (paralyzing but not killing them) and brings them back to the cell, into which she packs them.  When the cell is sufficiently stuffed with spiders, she lays an egg and seals the cell with more mud.  She makes and fills several of these cells and typically covers all of them together with a final layer of mud.  When the wasp egg in each cell hatches, the larva has living spiders to eat that haven’t decomposed, due to the fact that they are not dead. Eventually the larval wasp pupates and the adult wasp chews its way out of the cell.

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Great Spangled Fritillaries Flying, Feeding & Mating

8-10-16  gs fritillary 036

There are five species of fritillaries in New England: the Great Spangled, Aphrodite, Atlantis, Silver-bordered and Meadow.  The largest and most common is the Great Spangled Fritillary.

The adults are in flight now, feeding on the nectar of a variety of flowers, including Joe-Pye Weed (pictured), mints and milkweed.  In general they prefer long, tubular flowers.  Males patrol open areas for females.  After mating, female Great Spangled Fritillaries enter a resting state called diapause, which they emerge from in late summer.  At this time they lay their eggs near patches of violets (larval host plant) and die. The caterpillars hatch in the fall and overwinter as larvae, becoming active in the spring at the same time as violet plants begin to grow.  Feeding takes place at night, and is limited to violet leaves. Hopefully global warming will not upset the synchronization of these two events.

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Robber Flies Capturing Prey

8-3-16  robber fly 009The robber fly family, Asilidae, is one of the largest families of flies.  All robber flies are predaceous and are recognized by their long bodies, forward-facing beaks and a tuft of hairs above the beak.  You find them on the ground or on leaf tips and other sunny spots where they survey the area for flying insects.  Once a robber fly has spotted a suitably-sized prey, it darts out and impales it with its stout beak.  It then inserts its needlelike “tongue” into the prey’s neck, eye or other weak spot, immobilizing the insect and liquefying its innards with an injection of saliva that contains nerve poisons and enzymes that break down proteins. Finally, it drinks its meal.  Pictured is a species of robber fly in the genus Diogmites, whose members are known for dangling by a foreleg while dining.

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Case-bearing Leaf Beetles Eating & Growing

8-1-16 case-bearing leaf beetle 110It’s not every day that I discover a species I’ve never seen before, but when it comes to insects, it happens regularly.  Rarely, however, are they as interesting as the Case-bearing Leaf Beetle I observed on a blackberry leaf recently.  An oval, brown, stationary case about ¼” long was at a 45° angle to the leaf it appeared to be attached to it.  Upon closer inspection and with a bit of probing, a head and six legs appeared at the leaf end of the case, and the case began to move.

How its case was created is as, or more, interesting than the beetle itself.  The adult female Case-bearing Leaf Beetle lays an egg and wraps it with her fecal material as she turns the egg, until it is completely enclosed.  Once hardened, the feces create a protective case for both the egg and eventually the larva.  When the egg hatches, the larva opens one end of the case, extends its head and legs, flips the case over its back and crawls away.  As the larva eats and grows, it adds its own fecal material to the case in order to enlarge it.  Eventually the larva reseals the case, pupates and then emerges as an adult Case-bearing Leaf Beetle.  If it’s a female it then prepares to mate, lay eggs, and recycle its waste.

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Grasshopper Wings Growing

7-21-16  grasshopper wings 092Grasshoppers experience incomplete metamorphosis, with three life cycle stages – egg, nymph, and adult.  A grasshopper egg hatches into a nymph, which resembles an adult grasshopper, except that it is smaller and lacks wings and reproductive organs.  Because of its hard outer exoskeleton, a growing grasshopper has to shed its skin periodically to accommodate its increased size.  (A larger exoskeleton develops beneath the old, smaller one that is shed.) Grasshopper nymphs molt several times (each stage between molts is referred to as an instar) before they reach their adult size, and with each molt, their “wing buds” get larger.  After the final molt, the wings are inflated and become fully functional.  Wings play an important part in grasshopper courtship, as males “sing” to attract females by rapidly rasping their leg against their forewing, a process called stridulation.

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