"Treedweller" wrote in message
...
On Mon, 11 Apr 2005 08:38:07 -0500, J Rob wrote:
The little worms are called leaf rollers. They attack oaks every year
around this time, eating (and rolling up in, as a cocoon) the new
leaves. They are followed shortly by predatory insects (like tiny
wasps) and birds, who eat them. Some years, the worms boom, which
creates a happy time for the predators. Other years, the predators
are so bountiful (from previous worm booms) that they dominate, but
their population suffers because of a lack of food. Generally, the
boom-bust cycle takes care of itself--the worms run their course
quickly enough and the tree recovers without much trouble.

In the forest, in Caddo Parish, Louisiana, there are years when those
worms strip virtually all the leaves from the oaks. Their droppings are
tiny dry black spheres, and can be dropping so abundantly they sound
like drizzling rain. They uglify the oaks, but have never -- so far as I
can tell -- do any lasting harm to them.

Sometimes there are some stinging catapillars -- not numerous, thank
goodness. If they fall on your skin the area they touch burns and stings
and swells and turns red, very much like what happens when you brush
against a bull nettle.

I've always wondered what might happen if the heavy leaf-eating worms
would come in the same year as a drought. I've never seen the two in
the same summer. Drought (along with pine beetles and the beetles that
kill mature red oaks) is one of the most destructive enemies of trees in
in this region.

Knowing that some plants (that cannot be watered) sometimes weather
a drought better if they are cut back (to avoid dehydration)... I wonder
if the reduction in total leaf surface by catapillars might even confer
a slight advantage in a drought year.

Only someone knowing actual research results could say, for sure.


Keith Babberney
ISA Certified Arborist