Monday, June 13, 2011

Edwards' Hairstreak Pupa 2011

Once again I’ve failed to capture images of the final instar Edwards’ Hairstreak larvae. It helped ease the pain somewhat when I was poking around the base of one the oaks that had held larvae this year and found a pupa that was close enough to the surface to be rolled out for a photo shoot. This is the ventral surface showing the wing pads, eyes, antennae and legs.

It’s impossible to get a shot without one of the guardian ants in attendance. This is one of the Allegheny Mound Ants, Formica exsectoides, that cares for the butterflies from the larva through the pupa stage.

Several dozen of the ants used those formidable jaws to discourage me from taking pictures. I can usually take about three pictures before an ant gnaws its way down through the skin and demands attention. Fortunately, they don’t latch on with anything close to a death grip, so are easy to dislodge.

When I finished taking photos, I rolled the pupa back into the protective shelter built by the ants. It ought to be emerging as an adult in a couple of weeks. Check out Edwards’ Hairstreak in the Labels list in the side bar for more information on the butterfly and its relationship to the ants.

The ants have created several chambers at the base of this small oak. The older larvae were held in these chambers during the day and escorted into the tree to feed at night. The larvae eventually pupated below ground and are enjoying the protection of the ants until they emerge as adults.

This small tree is still recovering from the cicada emergence of 2008. It’s a scrubby looking tree, but it manages to produce a lot of Edwards’ Hairstreak Butterflies every year.

The larvae begin by eating the buds and then continue on to the developing leaves. Some of the leaves that look the most devastated were actually consumed when they were much smaller. After being eaten, they continued to grow until the veins and remaining leafy bits reached their normal size.

Signs of feeding activity are evident on many of the small oaks. I actually saw the young larvae on several of these trees earlier in the year. Once you get a visual image, it’s easy to pick out the feeding damage on the trees.

Every tree that showed signs of larvae activity, also showed signs of ant chambers constructed at the base of the trunk. Some look to have been used in previous years and others appear to have been recently constructed. It looks like there will be an abundance of adult butterflies this year.