Summer 1999

[TEXT ARCHIVE WEB-PUBLISHED MARCH 2002.
ORIGINAL PRINT PUBLICATION DATE: SUMMER 1999.]

Out Among the Aphrodites

By Joe Neumann

Whoosh! I swipe my net up and down, left and right. Bring on the butterflies. Our walk through Spears Woods in southwest Cook County has been pleasant but not particularly productive. This well-shaded woods has too few flowers to attract most butterflies. But now there is a light at the end of this tunnel.

…Out into the sun…All the stalks and stems are so fresh and flexible that they bounce off our bodies as we push through them. The Aphrodites are here in force — Aphrodite fritillaries, that is — all orange and airy. They pop from the growth and whirl around each other. You spin around, your eyes darting back and forth as you attempt to track them. This scene is the natural equivalent of a carnival hall of mirrors.

Andy and I are the volunteer butterfly monitors here. Thirty preserves throughout the Chicago region received such monitoring last year. Doug Taron of the Chicago Academy of Sciences and Ron Panzer of Northeastern Illinois University oversee the operation.

To ensure the scientific accuracy of our results, we walk along a set route, during set times (between 10 a.m. and 3 p.m.) and under set conditions (low wind and at least partial sun). I am the netter today. Andy is the recorder. He marks on a sheet the butterflies we find and the habitat we find them in. We count butterflies — we do not collect them.

Spears Woods has received extensive restoration work. Both Andy and I have helped clear the European buckthorn brush that threatens to clog this preserve. Since restoration began in 1990, much of the site has received a controlled burn. Monitoring butterfly populations is one way to assess the impact of the restoration work.

The Aphrodite belongs to a group of butterflies known as the greater fritillaries or silverspots. The one now lounging in front of me makes the origin of this name obvious. A deep maroon drapes its underwing and from among this backdrop a host of large silvery spots shine. Andy has seen the butterfly now too. "Get that one!" he says. There are fritillaries rarer than the Aphrodite. This one reclines on its flower utterly uninterested in escape. Whoosh! We transfer it from the net into a jar. The orange and brown pattern of its upper wing reveals that it is just an Aphrodite. But what an Aphrodite! The queen of the Aphrodites!

Our route leads us to an official trail. To the west lies a wetland that the Forest Preserve District dammed and now stocks with fish. Some backyard butterflies fly here, the red admiral and the ubiquitous white European cabbage butterfly. A cluster of dogbane, now in full flower, draws a flock of butterflies. Among these are several great spangled fritillaries, a more common cousin of the Aphrodite. This butterfly is beautiful in its own right but not as "habitat restricted" as the Aphrodite and so of less interest to us.

Since we entered this field, we have seen no Aphrodites. Year after year a stray Aphrodite is all we find here. This field appears much the same as the one to the south where we entered, and another field to the east. Yet both the south and east fields have healthy Aphrodite populations. More puzzling is the fact that for the first two years of monitoring, the south field was just as barren as this field. The explanation of this observation may not be simple, but one fact about these fields stands out. Since restoration work began the west field has never been burned, while the south field has been burned twice. The east field has also been burned twice, in different years than the south field.

The effect of fire on insects is controversial. The idea that fire harms insects makes sense, and Ron Panzer's studies show that many insect populations do decrease the year following a fire. But, counterintuitively, most of these species prosper in subsequent years. Ron recommends burning a third of an area each year so that the insects can, in effect, have their cake and eat it too.

Doug Taron has monitored the butterflies at Bluff Spring Fen near Elgin in far western Cook County since 1987. Restoration work, including extensive burning, has been conducted at the site since 1981. Doug's data show statistically significant increases in the populations of two rare, remnant-dependent species. The Aphrodite population at Spears Woods has now also shown a statistically significant increase since restoration work began.

We enter an oak ridge now that appears to have served as a property line in the past. Ahead of us, the east field opens. We descend into it, counting the butterflies as we go: Aphrodites, great spangled fritillaries and, weaving among the growth, the velvet black flutter of the first wood nymph of the season.