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Insect Eggs

Bagworm Moth Bags


If you find a tiny (1/2″ long) bundle of stick-like pieces of vegetation clumped together into a “bag” that is attached to a structure, you have discovered the abandoned home of a bagworm moth larva, and the overwintering site of bagworm moth eggs. The bags consist of parts of the vegetation that the larva was eating and then bound together with silk.

In the spring, the eggs hatch and the larvae all leave and build protective cases, or bags, for themselves, inside of which they live while feeding, growing and molting throughout the summer. As the larvae increase in size, they increase the size of their bags. Eventually the larvae attach the bags to branches, trees, etc. and pupate within them. Female bagworm moths are wingless, and thus are confined to life within a bag for their entire lives. Upon emerging, adult male bagworm moths seek out the females and mate with them before perishing. After laying eggs inside their bags, females exit and die.

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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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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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Caddisflies Laying Eggs

9-3 caddisfly eggs & larvae 402Most caddisflies lay their eggs in or near ponds or streams. A very few species (in the family of northern case makers, Limnephilidae) deposit their eggs above the water on aquatic vegetation in a one- to-two-inch-long mass of jelly (some species’ eggs lack the jelly). Up to 800 eggs (the tan spots within the jelly in yesterday’s post) are laid at one time in one mass. Depending on the species, the eggs take from several weeks up to ten months to hatch. These masses are usually situated so that once the eggs hatch, the larvae will drop down into the water, where they will spend their larval and pupal stages.

Caddisflies are closely related to butterflies and moths, and one of the features they have in common is that the larvae have silk glands in their lower lip. Thanks to the ability to spin silk, the caddisfly larvae build portable cases or attached retreats out of natural material that is available. Some species build elongate tubes out of pieces of plants, sand, sticks or pebbles and reside in them while they drag them along with them wherever they go. Other species attach their cases with silk to crevices in or the bottom of stones in streams. Each species of caddisfly larva always constructs the same type of case, so that you can often tell the genus or even species of caddisfly by the appearance of its case.

The larval stage of a caddisfly can last two to three months or up to two years, depending on the species. Most species spend the winter as active larvae. When it is ready to pupate, the larva attaches its case with silk to something immoveable, such as a large rock. Inside its case, the larva spins a cocoon and eventually pupates inside of it. In two to three weeks the sharp-jawed pupa cuts its way out of its cocoon and floats up to the surface of the water where it emerges as a winged adult, often using its pupal skin as a raft for support during this process. Adult caddisflies live for about 30 days, during which time the males form mating swarms to attract females. After mating takes place, the egg-laying begins.

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Black and Yellow Mud Daubers Collecting Mud & Building Cells

7-20-15 mud dauber 140There are many species of mud daubers — wasps that build mud cells in which they lay eggs and in which their larvae develop. The female Black and Yellow Mud Dauber gathers mud at the edge of a pond or puddle, rolls it into a ball, grasps it in her mandibles and flies it back to her nest site, a spot protected from rain, often on a man-made building. Here she constructs several mud cylindrical cells.

Like most wasps, mud daubers are predators, and they provision their mud cells with select spiders (including jumping spiders, crab spiders and orb weavers) which they locate, sting and paralyze before stuffing them into a cell. The female lays an egg amongst the spiders, so that when the egg hatches the emerging larva will have a supply of spiders (that haven’t decomposed, because they’re not dead) to eat. She seals the cell with mud, and repeats this process several times after which she covers the small group of cells with more mud. The Black and Yellow Mud Dauber larvae pupate in the fall, overwinter inside the cells and emerge as adult wasps the following spring.

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Mossy Rose Gall Wasp Larvae Cease Feeding

10-31-14 mossy rose gall IMG_0404In the spring, the 4mm-long cynipid gall wasp, Diplolepis rosae, lays up to 60 eggs (through parthenogenesis) inside the leaf bud of a rose bush. A week later, the eggs hatch and the larvae begin feeding on the leaf bud. This stimulates the abnormal growth of plant tissue, and a Mossy Rose Gall, covered with a dense mass of sticky branched filaments, is formed. The gall provides the larvae with food and shelter through the summer. In late October, when the Mossy Rose Gall is at its most colorful, the larvae stop eating and pass into the prepupal stage, in which they overwinter inside the gall. In February or March, the prepupae undergo a final molt and become pupae. If the pupae aren’t extracted and eaten by a bird during the winter or parasitized by another insect, adult wasps exit the gall in the spring and begin the cycle all over again.

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Dragonflies Laying Eggs

8-27-14  black-tipped darner 133Never let it be said that Naturally Curious readers aren’t creative thinkers (see guesses on yesterday’s post) ! The vertical slits in the cattail leaves were made by female dragonflies that were in the process of laying their eggs. There are many different egg-laying strategies employed by dragonflies. Many females in the group of large, strong-flying dragonflies known as “darners” (such as the pictured Black-tipped Darner, Aeshna tuberculifera) use their lance-like ovipositors (see photo) to insert eggs into plants stems such as cattail, sphagnum moss, rotting wood or wet soil. However, most species of dragonflies possess non-functional ovipositors. The eggs of many of these species are washed off into water during flight as the female dips the tip of her abdomen into the lake, pond, river or stream.

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