Larvae of the Eastern Tent caterpillar emerge by the hundreds from egg cases that encircle the twigs of their food trees—members of the Rose family like apple, cherry and hawthorn. They spin communal, webby enclosures in the forks of branches in late spring and summer. The unspectacular brown moths they metamorphose into produce more egg mass in late summer. The adults do not feed.
Black Swallowtail males (which, like many butterfly species are smaller than the females) often appear in late April and early May. The female is larger, lacks the yellow on the wings and has a blue wash above the tails. Black Swallowtails have yellow spots on the body; tigers have a yellow streak along each side of the thorax and abdomen in both morphs. Tiger Swallowtails are among the largest butterflies around, reaching 5” in wingspan.
Milkweeds and goldenrods are famous for being hosts to a tremendous variety of insects and other arthropods that come to eat or be eaten. Both adult and immature insects that eat milkweed at some part of their life cycle are poisonous to their predators because of the toxic cardiac glycosides contained in milkweed sap.
Most adult insects die by late fall, leaving the next generation behind in the form of eggs or pupa. Most insects are in their adult stage for only a few months, and many have a predictable flight period—a portion of the spring/summer/fall when we expect to see them. Mourning Cloaks and the Angle-wings are butterflies that overwinter in their adult stages; these are the first butterflies we see when things start to warm up in spring, and their caterpillars get first crack at the spring veggies.
Most adult insects die by late fall, leaving the next generation behind in the form of eggs or pupa. These three butterflies, Anglewing, Question Mark, and Eastern Comma overwinter in cracks and crevices in rock piles and tree bark.
The Giant Swallowtail is an impressive butterfly of the southern U.S. that that wanders quite widely in late summer. It strays into and sometimes breeds in Wisconsin. The upper surface of the wing is black with a dramatic, yellow stripe, and the underwing is yellow, which gives it a confusing appearance in flight. When Giant Swallowtails do breed here, the food plant of the caterpillar is Prickly ash, which is the northern-most member of the citrus family.