An email came into the office asking about the dearth of butterflies this year. Donna B. noticed the same thing, and asked me about them this morning at the workday (BTW, Thanks Jane, Donna, Nancy and Ken!)
I got to thinking about the subject, and related it back to the gypsy moth situation. We’re having a good gypsy moth year (in that there are a lot fewer of them around this year) because the cool, wet Spring was very conducive for the growth of a fungus that kills gypsy moth caterpillars. It turns out that those same cool, wet conditions could also be responsible for causing a drop in butterfly populations, and for the same reasons. Fungal pathogens of Lepidoptera larvae (caterpillars) thrive in the cool, wet weather we had this Spring and early Summer. The cooler weather, may also affect whether or not you’ll see butterflies. They are cold blooded, and so must bask in the sun to get warm enough to fly. These are just speculations, of course. If anyone has heard other reasons, put them in the comments section below the post.
Of course it could just be that evil West Nile guy killing them all!
Here is a googlebooks excerpt on the topic.