Friday, May 7, 2010

Edwards' Hairstreak Larvae

An Edwards' Hairstreak larva feeds on a young Blackjack Oak leaf. About 20 years ago I learned of the strange relationship between the Edwards' Hairstreak Butterfly and the Allegheny Mound Ants. I knew that Blue Jay Barrens contained ideal habitat for both of these species. After several years of searching, I finally discovered the adult butterfly. Last year I found the pupae. Now I’ve found the larvae.  I'll have to keep looking for the eggs.

As I examined the trees, it became evident that if there were ants on the buds, there were butterfly larvae. Most occupied buds contain three or four larvae and two or three ants.

The ant is about a quarter of an inch long, so the larvae would measure in at about a tenth of an inch. The larvae are constantly guarded by the ants.

This ant is tending a slightly older larva. After their third molt, the larvae will begin producing honeydew upon which the ants will feed. It’s thought that the ants protect the larvae in order to protect this honeydew supply, but no one knows what prompts the ants to protect the young larvae that produce no reward.

The ants are very attentive and frequently stroke and lick the larvae. Maybe the larvae exude the promise of honeydew and this is enough to keep the ants on guard.

The ants apparently tend mixed species herds. Between the two branches can be seen a butterfly larvae, while on the front of the green stem is some type of planthopper nymph, both enjoying the protection of the ants.

The larvae and nymphs seem to get along together. A butterfly larva is laying up against the pronotum of the planthopper.

This may be what the nymph is destined to become. Sorry, I seem to have drifted away from the Edwards' Hairstreaks.

1 comment:

  1. Fascinating information! Who would have ever thought that there would be such a relationship going on between ants and butterfly larvae? Wow. ~karen