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Invertebrates

Funnel Weaving Spiders Spinning Last Webs of the Year

10-16-14 funnel weaver web 045A number of unrelated spider families in North America spin webs with funnel-shaped retreats. These spiders are all referred to as funnel weavers. The spider lies in wait in the funnel, and when an insect flies into or lands on the web, the spider rushes out, checks to see if it is prey, and if it is, bites it. Its venom is fast-acting, and as soon as the prey is largely immobile, the spider drags it back into its funnel to safely consume it out of sight. Many species’ funnel webs are horizontal, and found in grass and bushes, but others are vertical. Like most spiders, funnel weavers are nocturnal. Many species die in the fall, but a few live a year or two. If you find a funnel web inhabited, it is likely to be a female. Males spend most of their life wandering in search of a mate, and after finding one and mating a few times, often die.

Funnel weaving spiders are docile and non-aggressive, and their bite is rarely as bad as a bee sting. Funnel weaving spiders are sometimes referred to as “funnel web spiders.” True funnel web spiders are not found in North America, but in Australia, where their bite is considered harmful.

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Saddleback Caterpillars Preparing to Pupate

10-6-14 saddleback moth 006There is a group of moths (family Limacodidae) which are known as “slug caterpillar moths” due to the manner in which they travel during their larval stage, secreting a semi-fluid silk from their ventral pores as they move. These caterpillars come in all sizes and shapes. Among them is the Saddleback Caterpillar, which is much more colorful than the brown adult moth it eventually turns into. Saddleback Caterpillars are best known for their stinging (urticating) spines. Reputedly far worse than that of a bee, the sting of the Saddleback Caterpillar may be the most potent of any North American caterpillar. The larva’s bright colors serve to warn predators of its toxicity. Soon these caterpillars will be spinning cocoons (which can contain spines, as well) in which they will pupate until emerging as moths next spring. (Thanks to Rick Palumbo for photo op.)

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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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Second Brood of Woolly Bears Hatches

8-18-14  woolly bear 093Typically we start seeing Woolly Bear caterpillars in October, when they are searching for sheltered spots in which to spend the winter as larvae. With only two months between now and then, it came as a surprise when my great nephew and budding naturalist Eli Holland discovered a very young Woolly Bear recently. It turns out that in New England, there are two broods of Isabella Tiger Moths (whose larval stage is the Woolly Bear). The caterpillars that hibernated last winter emerged from hibernation this past spring, pupated, transformed into adult Isabella Tiger Moths, and proceeded to mate and lay eggs. It is these eggs that have recently hatched, and the Woolly Bear caterpillars that are no bigger than the length of your baby fingernail right now will be eating dandelions, grasses, nettle and meadowsweet nonstop for the next two months in order to survive the coming winter.

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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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Robber Fly Mimics Bumblebee

8-4-14  robber fly like bumblebee2 054Milkweed leaves make excellent platforms for all kinds of insects, particularly those such as dragonflies and robber flies, which sit, wait and watch, surveying the landscape for prey to ambush. This robber fly could quite easily be mistaken for a bumblebee. However, the short, straight antennae and the presence of only two wings (instead of four) tell you it’s in the order Diptera (true flies). The pointed, stout proboscis, bearded face, fleshy feet and long, tapering abdomen narrow it down to a species of robber fly. Robber flies in the genus Laphria resemble bumblebees – they are typically quite hairy, with black bodies and yellow stripes on their abdomens. Like other species of robber flies, they hunt by perching and snagging prey such as other robber flies, bees, wasps or beetles. They often return to their perch, inject the prey with enzymes that dissolve its innards, and then have a long drink. Why mimic a bumblebee? To deceive unsuspecting honeybees, wasps and other insects that would make a good meal.

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Clymene Moths Active

8-4-14 Clymene moth 140The Clymene Moth, Haploa clymene, is noted for the striking upside-down cross pattern on its forewings. Because of this design, some people refer to it as the “Crusader Moth.” A member of the Tiger Moth family (as is the Woolly Bear/Isabella Tiger Moth), the Clymene Moth can be seen flying day or night. Typically they inhabit deciduous forests and fields adjacent to them where the black, bristly larvae feed on a wide variety of plants, including willows, oaks, and members of the Aster family. In contrast to its white forewings, the Clymene Moth’s hind pair of wings is bright yellow. Its long proboscis allows it to reach deep inside the nectar-bearing hoods of Common Milkweed.

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