Wednesday, October 03, 2007

Silver spotted skippers


I first saw this large skipper last fall, hovering over a mound of purple asters in my native plant bed. To be honest, I was downright lazy in my pursuit to identify it. I flipped through Butterflies of Missouri looking for a nice color plate. I looked through the butterfly and moth sections, but completely ignored the thick mass of pages dedicated to skippers, generally small insects that noticeably "skip" from plant to plant. The silver spotted skipper was too large, I thought, to be a skipper.

This spring, when they appeared by the droves on my pink zinnias, I was finally forced to figure out who they were. For some reason, the name "gray spotted checker"--an abomination of three other insects, the gray hairstreak, spotted skipper and checkered skipper-- stuck in my head. All summer I called the silver spotted skipper a gray spotted checker. I said it with such conviction that even my herpetologist remembered the name until he tried looking it up. Times like this, when I'm obviously wrong, Alyssa laughs hysterically, she bends over at the waist in delight. I hope my herpetologist did the same thing.

To make up for my negligence towards learning this insect, I've gorged on its natural history. My entomologist has fed me some fun facts about silver spotted skippers and I've finally consulted all of my departmental books. Skippers belong to a large family, the Hesperiidae, that includes several thousand species. Most skippers generally have rather stout bodies and small wings. The larvae prepare their nests by curling leaves around the cocoon; the skippers that feed on grasses web blades together for shelter. The silver spotted skipper is the largest skipper in Missouri, which is probably why I didn't think it was a skipper.

This skipper, the most common skipper in my zinnia bed, is responsible for my lack of fresh lima beans, fresh flageolets, and fresh heirloom haricot verts this summer. The silver spotted skipper larvae feed on members of the Fabaceae family, the pea family. While the adults traditionally lay their eggs singly on woody members of the family like honey locust and false indigo, they will just as easily lay their eggs on bean plants, encouraging the larvae to devour all of the plant's leaves in a matter of days. Considering that 92% of my county is planted in soybeans, which are also members of the Fabaceae family, the commonality of silver spotted skippers is no mystery. They are an identified crop pest and can be "treated" with a gnarly combination of pesticides. Of course, I just let them have their way. If I'm not meant to have beans, I'm not meant to have beans. I still have the all-important tomatoes and basil and a great patch of oregano. Nevertheless, a single caterpillar can destroy 50-70% of the leaves of a single bean plant.

My entomologist works part-time for local farmers identifying crop pests. He has discovered that more silver spotted skippers live in RoundUp Ready soybean fields than in the area's few pristine woodlands. Because the skippers have lived for so long around pesticides, the larvae are now resistant to RoundUp. While this is utterly disheartening for so many reasons, it's also somehow...good? that they're not being killed by an herbicide. They still manage to exist in high numbers, despite the presence of toxic chemicals that are systemically grown into their food source.

Silver spotted skippers only visit nectar sources that are pink, purple, blue, red and white. They don't visit yellow flowers very often, which explains why I only see them on my zinnias and not on my goldenrod and asters. With a food source so widely available as soybeans in southeast Missouri, this is one insect that is holding its ground in light of the terribly depauperate habitat.

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