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Insects

Bottle Gentian’s Pollinators

9-17-14  bottle gentian 259The combination of Bottle Gentian’s (Gentiana clausa) blossoms’ brilliant purple/blue color, their shape, and the difficulty insects have in prying open the bottle neck their petals form, make them a highlight of every September. Getting inside their flowers is a monumental task, and one that few insects, other than fairly large species of bumblebees, attempt — much less accomplish. It takes several seconds of pushing, shoving and cramming to get their head through the miniscule opening at the top of the blossom. Eventually their body follows, sliding down into the flower. While the whole bee sometimes disappears, it’s more usual to see their hind legs poking out of the flower while they lap up nectar. Not only are bumblebees strong, but their tongues (see insert) are long enough to reach the copious amount of sugar-laden nectar that awaits them inside the flower.


Milkweed Tussock Moth Caterpillars Feeding

milkweed tussock moth2 038Female milkweed tussock moths lay their eggs in masses on the underside of milkweed and dogbane leaves, which their larvae will eat. The hatching caterpillars are gray and hairy, but in no time they have developed the tufts of hairs that give them their name and make them resemble little mops. When still fairly young, the siblings stay together, skeletonizing the leaves they consume, leaving only the strongest veins that contain sticky latex. As they mature, the caterpillars tend to wander, and it’s unusual to find large groups of them on a single leaf. At this point they often cut through a vein in order to prevent the latex from reaching the area of the leaf where they are feeding. (Older monarch caterpillars use this same tactic.) Like monarchs, milkweed tussock moths, because they’ve consumed the cardiac glycosides contained in milkweed and dogbane leaves, are toxic to predators.

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Queen Ants Mating & Removing Wings

ant removing wings2  095Ants are social insects and live in colonies consisting of one or more queens, female workers and males. In most species the non-sexually mature female ants are wingless; only the males and the queen(s) possess wings. Periodically, often 3-5 days after a heavy rain, the winged ants emerge from the colony in large swarms in order to mate and create more colonies. Swarming behavior is usually synchronized with other nearby colonies, so large numbers (hundreds or thousands) of winged ants suddenly appear. After mating, the males die and the queens shed their wings and use the remaining wing muscles as a source of nutrients during the early stages of colony development. The shedding of wings is not a passive activity. The pictured ant is in the process of removing her fourth and final wing. She held each wing down with one leg while pulling it out with another. She then crawled off, leaving a pile of wings behind.

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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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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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Goldenrod Bunch Gall

goldenrod bunch gall 144Galls are abnormal plant growths that are caused by a number of agents, including insects. Each gall-making insect has a specific host plant and location (leaf, stem, bud) on which it lays its eggs in the spring, during the growing season. The egg-laying and/or hatching and chewing of the larva causes the plant to react by forming a growth around the insect. Galls of different species of insects vary in their shape and the gall maker can often be identified as a result of this.

Goldenrods are host to about 50 species of gall-making insects, two-thirds of which are midges, or tiny flies. Goldenrod Bunch Galls, also called Rosette Galls, are the result of an egg being laid in the topmost leaf bud of Canada Goldenrod, Solidago canadensis by a midge in the genus Rhopalomyia, often Rhopalomyia solidaginis. The stem of the goldenrod stops growing, but the leaves don’t. The resulting rosette of leaves provides shelter and food for the midge larva, as well as a host of other insects, including other midges. Adult Goldenrod Bunch Gall midges emerge from the galls in the fall, and females lay eggs in the soil. The larvae hatch within one to two weeks and spend the winter underground, emerging in the spring to start the cycle all over again. Interestingly, Rhopalomyia solidaginis lays all male or all female eggs, one or the other.

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Grasshoppers Courting, Mating & Laying Eggs

8-20-14 mating grasshoppers 040It’s that time of year again, when grasshoppers are courting, mating and laying eggs that will overwinter and hatch next spring. In addition to adopting different poses and flashing brightly-colored wings, male grasshoppers attract females by producing calling songs. (Some females also produce sounds, but they are usually infrequent and very soft.) The males rub their hind femur against a forewing, or rub a forewing against a hind wing in order to make their calls, a process called stridulation. Tympana, or eardrum-like structures on their abdomen, allow both male and female grasshoppers to hear. Because the songs are species-specific, females can readily identify males of the same species.

After pairing up, the smaller male grasshopper usually mounts the female and the female curls her abdomen up to reach the male’s reproductive organ (aedeagus) from which she receives a package of sperm called a spermatophore. The mating process can take from 45 minutes to more than a day, depending on the species. The small, pointed structures that you see at the tip of the female’s abdomen are her ovipositors, with which she deposits her eggs in the ground.

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