Thursday, July 1, 2010

Edward's Hairstreak

Last Saturday, June 26th, I was helping with the Adams County, Ohio butterfly count. On the count, we encountered a beautiful little butterfly called Edward's Hairstreak, Satyrium edwardsii.

The butterfly has an interesting life cycle. In the summer, the butterflies lay their eggs in the cracks and crevices of the bark on young oak trees. The following spring, the eggs hatch and the larvae feed on the tender new oak leaves. Here comes the interesting part. They are also tended by ants. These ants, Allegheny Mound Builder Ants, Formica exsectoides, construct huge mounds near the oak trees. They nurture the Edward's Hairstreak larvae, following them up and down the tree, keeping them safe from predatory wasps and other beasties. The ants also construct shelters called byres at the base of the oak tree. They can be 4 to 10 inches in diameter and 2 to 8 inches tall. The larvae feed at night and retreat into the byre at first light. In return, the ants are given a reward of tasty honeydew, a sweet substance the larvae secretes.

Here is a picture of one of the mounds I took at Adams Lake in 2008. The mounds are large, about 2 to three feet in height. I also discovered if you get too close to the mound, the ants will let you know by giving you a sharp nip. Ouch! I had sandels on, at the time, and did a little dancing to get them off my feet. :)

Above is a great pic by John Howard of the ants tending to the larvae. Gentle stroking with their antennae will produce the honeydew they so crave.

The larvae will also pupate inside the byres. You can view pics of the pupa and other great pics of Edward's Hairstreaks at Steve Willson's blog, Blue Jay Barrens.

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