At a certain stage in the development of an Edwards’
Hairstreak Butterfly larva, it will begin feeding at night and hiding at the
base of the tree during daylight hours.
I’m trying hard to witness this daily migration of the larvae up and
down the tree. On a recent early morning
visit to a small oak hosting a family of caterpillars, I was lucky enough to
find a larva that was still actively feeding.
Allegheny Mound Ants normally keep close company to the
larvae. The larva receives protection
from the ant and the ant is rewarded with a bit of sweet honeydew secreted by
the larva.
The ant may patrol the near vicinity, but it is seldom more
than an ant length from the larva. When
the early morning sunlight illuminated the larva, it left the leaf and began
its journey down the tree.
From the reading I have done, I thought the larva would move
at a slow pace. I was surprised at the
rapid pace at which the larva actually traveled. It wasn’t nearly as quick as an ant, but it
made a respectable retreat down the stem.
I also thought that the ant would give more direction to the
larva. The behavior of the ant suggested
that it was just following along in an attempt to keep with its source of food. There’s got to be more to the association
than just a bit of food, because the larva only produces honeydew during the
final stages of its development, but the ant protects it from the time the
larva hatches from the egg until the winged adult butterfly emerges from the
pupa.
The larva didn’t slow upon reaching the trunk. The downward trek continued at a constant
pace.
When it emerged into a band of sunlight, it stopped. Its reaction was like that of a typical movie
vampire. At the first touch of sunlight,
it quickly reversed course.
It finally tucked itself into a protected area of the tree
bark and stopped. It appeared to be
settling in for a long stay, so I didn’t stick around to see if it resumed its
journey when the shade finally covered the rest of the tree trunk.
There’s evidence of feeding on many of the oaks. I hope this year to witness the night time
feeding and the mass migration of larvae heading down the tree towards daytime
shelter.
Note: Piece together the whole story by clicking on Edwards’
Hairstreak in the list of labels.
Cool observation! I hope you're able to capture and post the mass migration.
ReplyDeleteWonderful documentation of one of nature's small, but fascinating stories.
ReplyDeleteHi Troy. I'll do everything I can and just hope the caterpillars cooperate.
ReplyDeleteThanks Pat.