One morning multiple 1”-2” white blotches appear on the screening of your porch or windows. They weren’t there the previous day, so they had to have been deposited during the night. What nocturnal creature is responsible and what exactly are they?
A close look reveals that each white patch consists of hundreds of minuscule white balls – eggs that an insect must have deposited. Their size, shape and coloring indicate that they were most likely produced by Owlet Moths or noctuids, members of the Noctuidae family. Owlet Moths make up over 25% of all butterflies and moths — there are 75,000 known species worldwide with thousands yet to be identified. Most adults are a fairly drab shade of brown and are well camouflaged with lines and spots that resemble tree bark or bird droppings. (Moth coloring often resembles the bark of the food plant its larvae prefer.) Owlet Moth larvae are relatively hairless and are referred to as cutworms or armyworms (they can occur in destructive swarms and cut the stems of plants). Several species are serious crop or garden pests.
A majority of the moths in this family are nocturnal and are attracted to light. After mating, female Owlet Moths produce between 300 and 1,500 eggs, depending on the species. Newly laid eggs are spherical and often cream color but may turn yellow, orange, pink, red or gray within a day. Those laid this fall will overwinter and larvae will hatch in the spring.
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There is a family of flies, Tachinidae, which consists of different species of parasitic flies, one of which is Epalpus signifier. If you look at enough dandelions this time of year, you are likely to spot one — their white rump is a distinctive identifying feature. This fly is technically a parasitoid, and as such, spends most of its life attached to or within a host organism (Noctuid moth caterpillar) , getting nourishment from it. Unlike a parasite, it eventually kills or consumes its host
The striped caterpillar that is crawling along the surface of fresh snow is the larval stage of a noctuid or owlet moth (species unknown). Noctuids are dull-colored, medium-sized, nocturnal moths that are attracted to lights in the summer. They usually possess a well-developed proboscis (mouthpart) for sucking nectar. You may be familiar with the common garden pests, cutworms, which are also noctuid larvae. How this larva survives freezing temperatures I do not know, but I have seen several dozen at a time crawling around on top of the snow. Note: Jean Harrison, a fellow nature lover, just identified this larva as Noctua pronuba, a winter cutworm also known as the greater yellow underwing (moth), a recent immigrant from Europe.