The eggs laid last summer by the Edwards’ Hairstreak
butterflies have recently hatched and the buds of the Blackjack Oaks on the
barrens are now full of Edwards’ Hairstreak larvae and their attendant Allegheny
Mound Ants.
Most of the action takes place on these small Blackjack Oaks.
The Edwards’ Hairstreak butterflies sometimes lay their eggs on the larger
Oaks, but it’s much more likely that they will use an oak that is less than 6
feet tall.
In order to consume the sweet secretions, called honeydew,
produced by Edwards' Hairstreak larvae, Allegheny Mound Ants stand guard and
protect the larvae from predators. The
ants protect the larvae from hatching until emergence of the adult butterfly,
even though the larvae only produce honeydew during the final few instars prior
to pupation. This type of behavior,
where two different species interact to each species benefit, is called
mutualism. In the photo above, two larvae are located just to the left of the ant's head.
The larvae tend to begin feeding at the base of the bud.
Leaves that unfurl in a couple of weeks will be laced with holes made by the
larvae munching their way through the bud.
Blue Jay barrens has four different Prairie openings that contain
quantities of young Blackjack Oaks. I found Edwards’ Hairstreak larvae on trees
in all four areas. Some of the buds were really loaded down with larvae. There
may not be anything left of these buds to produce leaves later on.
The key to finding the larvae is in finding the ants. If there are no ants on the tree, there are no larvae. In a
couple of cases, ants congregated to protect tree hopper larvae, which also
form a type of honeydew. Even in these instances there were butterfly larvae
feeding at the same location.
On occasion I would get a bit too close with the camera,
causing an ant to take action against me. In each instance, I would direct the
ant back onto its bud so it could continue with its duties.
I have been nurturing small Blackjack Oaks at Blue Jay
Barrens in hopes of expanding the population size of the uncommon Edwards’ Hairstreak
butterfly. I’ve been seeing signs of success during the past couple of years,
but this year, the quantity of young larvae far exceeds anything I have seen in
the past. The ants have always been present, and now the addition of more trees
means more butterflies. The numbers of adult butterflies should be truly
amazing this summer.
I’ve included a couple of short videos showing Allegheny
mound ants interacting with the Edwards’ Hairstreak larvae. You can watch the
above video on YouTube by clicking HERE, or the below video by clicking HERE.
Nature is always so fascinating!
ReplyDeleteHi, Stew. I agree.
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