Steve Lekwa: Butterflies of late summer

Steve Lekwa
A Monarch butterfly takes flight after getting nectar from a flower.

Butterflies aren’t as common as they once were. I tend to stop and watch whenever I see one because it doesn’t happen very often anymore. 

Butterfly numbers tend to peak in late summer, but the drought that’s developed across Iowa will make things more difficult for them this year because nectar producing flowers will be fewer. 

Monarch butterflies may find enough milkweeds for their larvae to eat. It takes a great deal of energy for them to migrate, though, and all of it must come from flower nectar. They must find new sources of nectar each day as they move across the country toward Mexico. 

Some of the largest and showiest butterflies Iowans might see are the swallowtails. They are non-migratory, and three species might be seen here. The large yellow and black Eastern Swallowtail is a showy favorite. While the males are always yellow with black stripes, some females are quite dark. Even the dark females still show shadows of the black stripes. Their larvae eat leaves from cottonwood, cherry and a few other trees.

Black Swallowtails are slightly smaller. Males are black with yellow spots along the rear edge of their wings. Females have much smaller yellow spots. Their larvae eat wild and cultivated plants from the parsley family. 

The Giant Swallowtail shows mostly black on the upper wing surfaces with rows of yellow spots and mostly yellow underneath with a few black markings. Their larvae eat plants from the citrus family. In our area that means only the prickly ash bush, a relatively common woodland plant.

Fritillaries are orange and slightly smaller than monarchs. They show black spots on the upper side and silvery spots on the underside. 

The Great Spangled Fritillary was common some years ago but is less so today. The Regal Fritillary was common before the prairies were plowed under but is listed as endangered over much of its former range. It can still be found on a few native prairie preserves (including Doolittle Prairie here in Story County). Its hind wings are dark with large silvery spots above and below. All Fritillary larvae feed on violets, but Regal Fritillary larvae are much more choosy, feeding only on prairie violets.

Iowans may see two butterflies from a group known as anglewings because their wings show ragged sharp angles on the trailing edge. The medium sized Question Mark and Eastern Comma are orange and black above and camouflaged gray and brown below. They’re named for a small, silvery “punctuation mark” visible on the under side of the hind wing. 

The larvae of these woodland butterflies eat the leaves of hops, nettles and elms. The Question Mark may hibernate as an adult and fly again in the spring. Don’t look for these around flowers, though. They feed on dung, rotting fruit, tree sap and carrion.

The “brushfoots” are closely related to anglewings and include several Iowa butterflies.  The monarch-sized dark brown Mourning Cloak is the largest. This butterfly sports a yellow band along the trailing edge of the wings. Adults live longer than most butterflies (up to 10 months), and might be seen flying on a warm late winter day. The larvae feed on willow, cottonwood, elm and birch. 

The medium sized Red Admiral is also mostly dark brown on the upper wing surfaces, but sports bright red-orange bands across the wings. The under side of the wings are more camouflage mottled. Their larvae feed mostly on nettles. 

The common American Lady and Painted Lady are mottled orange and black above and below. Adults winter over in the south and migrate north each spring to recolonize the continent. Their larvae eat a variety of plants including thistles and pussytoes.

There are many more species of butterflies in Iowa, but last group I’ll mention includes the Whites and Sulphurs. Anyone who raises cabbage, cauliflower or broccoli knows the larvae of the Cabbage White butterfly. House wrens are pesky for bluebirds, but they earn their keep eating those “little green worms” in a garden.

 Sulphurs, those bright yellow butterflies of summer with black edges on their wings, 

could be seen by the thousands when farms used to have fields of alfalfa and clover.  A few can still be found wherever there are patches of legumes that are their preferred food.

Steve Lekwa

The first asters and goldenrods are beginning to bloom. Their favorite nectar sources are thistle flowers. Butterflies will need every nectar source they can find this year.

Steve Lekwa is the former director of Story County Conservation. Contact him at 4lekwas@midiowa.net.