Friday, August 1, 2014

Silver-spotted Skippers

Silver-spotted Skipper Butterfly sharing a meal with a European Honeybee on Hoary Mountain Mint.

     I'm now back from my vacation and am ready to continue the Blog. Since there has been conversation among the environmental community regarding how few butterflies there are this year, I thought I would talk about one kind that is having a very good year. Silver-spotted Skipper butterflies (Epargyreus clarus) are very common this year and most others because they can use a variety of both nectar and host plant (caterpillar food) resources. The caterpillars can feed on most kinds of legumes, though Black Locust trees are among their most favored, perhaps because they are so large and common in our area. Male skippers will often stake out a territory around a patch of host plants and fly out to investigate any thing that ventures in. If it's another male they will chase it out; if it's a female, then they will pursue her. Occasionally they challenge a bird or dragonfly and pay the price for it. They often return to the same perch to watch over their chosen territories.

A Silver-spotted Skipper oviposits an egg under the shelter of a Black Locust tree.

     The photo above shows a female that is ovipositing (laying) her eggs on protected areas of Black Locust. She will land and "drum" the leaf surface with her feet, "tasting" it to make sure she has some form of leguminous plant before depositing them. She generally spreads her eggs out and does not lay more than one egg per leaf. 

The folded leaf shelter of a Silver-spotted Skipper caterpillar on its host plant.

     The caterpillars make shelters to hide in by folding a leaf over themselves and holding it together with silk. As they get bigger they make bigger shelters or may even pull several leaves together to conceal themselves. Their leaf hide-aways are very clean and made fresh regularly. They actually fling their frass (droppings) away from their shelters, helping prevent any predators from detecting and finding the larvae. They can sometimes project their frass up to 5 feet away, remarkable when you realize how small the caterpillars themselves are.

The fake eyes of a Silver-spotted Skipper caterpillar threaten you once you open its shelter.

     If you open up their shelter, you may be surprised by what they look like. Like most skipper butterfly caterpillars, they have a constricted "neck" that gives them a fat-headed appearance. But it's their fake eyes that may startle any potential predator. They will sometimes wiggle around and even open and close their mandibles in a threatening manner in the hopes they can frighten the intruder away. They are of course completely harmless, but it is always neat when I lead a walk and reveal what's hiding sometimes in the bushes or patrolling the air.

1 comment:

  1. Just had a silver skipper femal land on me and it looked like she was laying eggs on my legs and toes. She drummed with her feet, then curled her ovipositor and pushed out a clear bubble. Then she spread it around with her tongue. I couldn't see any eggs, but perhaps they were too small. She kept coming back to me and doing this over and over. Perhaps I tasted leguminous. Any thoughts?