Beautiful wood-nymph (Eudryas grata), Willistown PA. September 2017.
This caterpillar is a consumer of vines in the Mid-Atlantic, eating grape, Virginia creeper, and even porcelainberry. Adults mimic the appearance of bird droppings to avoid being eaten, whereas the caterpillars sport beautiful stripes with orange, speckled bands. This coloration may hint that the caterpillar is toxic if eaten, and given that the caterpillar sticks out against a green background, it may be one reason why so many wood nymphs survive to adulthood.
At least one generation in the Mid-Atlantic. Caterpillars overwinter as pupae, and bore into the wood of nearby trees to protect them through the cold winter months.
Rough stink bug (Brochymena quadripustulata), Willistown, PA. September 2017.
Also known as tree stink bugs, these insects appear like flecks of tree bark, helping them blend into their plant hosts, where they feed on the sap of leaves and tender shoots. They feed on a variety of trees and shrubs in the eastern US, although they can be commonly encountered on black walnut (seen here). As the name implies, the rough stink bug releases a putrid odor from glands beneath its second set of legs if threatened (although it is mild compared to more invasive stink bugs).
One generation in the Mid-Atlantic. Adults overwinter in plant litter or in crevices of trees, and lay eggs in the spring.
Fall Webworm (Hyphantria cunea), Willistown, PA. September 2017.
Here’s a caterpillar most find unwelcome on their properties. As the name implies, fall webworms form large tents in trees during late summer into fall, where they can feed on leaves without being attacked by predators (although many parasitic wasps find their way in). Other tent-makers, such as the eastern tent caterpillar, occur in the Mid-Atlantic around mid-to-late spring, helping separate the webworm from similar species.
The fall webworm can feed on over 600 different species of trees and shrubs, and may have the widest range of host plants for an insect in the world.Often caterpillars defoliate the branches they feed on, and in large numbers, even the trees. Only when the caterpillars are mature do they leave the safety of these tents, wandering to other plants and preparing to pupate.
Around two generations in the Mid-Atlantic, with caterpillars common in late July, and again in late August through September.
Large milkweed bugs (Oncopeltus fasciatus), Willistown PA, September 2017.
This is a commonly seen insect in fields, vacant lots, or any garden where milkweeds may be planted. Milkweed bugs are specialist feeders on milkweed plants, specifically the seedpods.
Their striking orange and black colors, like other milkweed-specialists, warn predators of the toxic chemicals the insects accumulate in their bodies.
Females lay their eggs in the crevices of the seed pods, protecting them from harm, and the immature nymphs feed en masse on the pods throughout their lives. As milkweed plants die out in the colder months, the insects migrate south towards the Gulf Coast to overwinter. The insects return in the summer as new milkweed plants establish.
At least one generation a year in the Mid-Atlantic.
Hickory Tussock Moth (Lophocampa caryae), Willistown PA. September 2017
A caterpillar that feeds on over 100 different species of plants, the hickory tussock moth is a common caterpillar in the garden, the meadow, and the forest. Caterpillars tend to stay together as they feed (aggregate) at early molts, but later spread out as they develop their characteristic black-and-white tufts of coarse, unpalatable hairs (you can see the remains of a previous molt in the photo above). The hairs do not sting and are otherwise harmless to humans, although exposure over time can lead to hypersensitivity.
One generation per year in the eastern US. Adults are active by late spring, and caterpillars are common July into autumn. They overwinter as pupae.
Spotted Phosphila (Phosphila miselioides), Newark DE. September 2017.
Caterpillars of the spotted phosphila feed exclusively on greebrier (Smilax spp.) in the eastern US, and can be found on forest edges and woodlots where the vines grow in abundance. Other species in this genus are also specialists on greenbrier, and can even be seen feeding on the same plant, but the spotted phospila prefers to feed on new growth. When startled, caterpillars will curl themselves up, retract their head into their thorax, and press their heads down to avoid harm.
One generation in the Mid-Atlantic, but at least two “broods” appearing in the summer. Caterpillars common in late spring and into autumn. Caterpillars overwinter as pupae.
Caterpillar from Newark DE. September 2017.Adult from Fishers Island, NY. August 2017.
A common prominent caterpillar throughout the eastern US, variable oakleaf caterpillars can be found on many woody plants, although oak trees are common host plants (the caterpillar was found on willow oak). The name is given to the caterpillar due to the variable markings on their thorax and abdomen.
Although a tasty meal for many songbirds, the variable oakleaf caterpillar has a novel defense to protect itself from predation. A gland in its thorax releases a spray of formic acid when provoked, releasing a vinegar-like smell to the air and can cause irritation or blistering to the skin of humans. Use caution when collecting caterpillars, preferably holding the leaf they sit on instead of the caterpillars themselves.
Two generations a year in the Mid-Atlantic, with adults common by mid-summer. Caterpillars overwinter as pupae.
Smeared dagger moth (Acronicta oblinita), Newark DE. September 2017.
Although this caterpillar can feed on many woody and herbaceous plants, it is often known as the “smartweed dagger” because caterpillars are commonly found on smartweed (Polygonum sp.). The caterpillar’s life history, being one of the few dagger moths that does not bore into the wood of its host plant prior to pupating, may suggest that it originally developed on smartweed plants before branching out to other hosts.
The beautiful color of the caterpillar, like a smear of paint, helps it blend into a flowering meadow (such as the background of goldenrod plants in the picture). Although the hairs are not stinging, those who handle the caterpillars may find themselves developing an allergy to them over time.
Two generations in the Mid-Atlantic, with caterpillars common by late spring and again in late summer. Caterpillars overwinter as pupae in the leaf litter.
Scorpionfly larva (Panorpa sp.), Ridgley, MD. September 2015.
Uncommon in insect collections, scorpionflies are unusual in appearance for both adult and immature forms. As larvae, they look much like caterpillars or sawflies, but have large compound eyes rather than a single or a small grouping of ommatidia. This is a unique feature that keys most scorpionflies out from other larvae.
Larvae are mostly soil-dwellers, rooting through litter of forest floors for dead insects and other arthropods. As adults, they become vultures of the insect world, winged scavengers consuming dead or dying insects, and may even rob a spider’s web of dead insects for later consumption. The term “scorpionfly” refers to the male genitalia of the males, which resembles a scorpion’s stinger.
A far better picture of the larva and adult can be found below.
(Photo by Pierre-Marc Brousseau from BugGuide.net)
(image of adult Panorpa sp. by Shannon Schade, also from BugGuide.net )
White-marked tussock moth (Orgyia leucostigma), Newark DE. September 2017.
One of the most common caterpillars to encounter in the eastern US, the white-marked tussock moth is often seen in late summer, where mature caterpillars sport their white hair tufts alongside a mottling of gray, yellow, and red. They are capable of feeding on both deciduous woody plants as well as conifers, and are considered one of the most generalist feeders of caterpillars in North America.
White-marked tussock moths are unusual in much of the moth world, as their females are wingless (a link to the adults can be found HERE).
Multiple generations a year in the Mid-Atlantic, with caterpillars from late spring onward. The eggs of the fall generation will overwinter.