Oak Trees with Bumpy Leaves

[I Don't Like Spam!]

On Tue, 21 Aug 2001 02:08:44 -0500, "B S Stone" <news at 1netcom.net>
wrote:

>All summer when I walked my dog I would pass by oak trees with bumps growing
>on the leaves. I have tried to look them up on the net but with no luck  I
>have lived in Texas all my life but never saw anything like this.  Is it
>seeds forming or is it an insect or fungus??
>
>It's been making me crazy wondering what it was.  Thanks, Brenda
>
>http://1netcom.net/images/leaves.bmp

Most likely an insect gall. Insects lay their eggs inside a leaf or
stem, and the plant produces a gall in response to the egg or
developing insect larva/pupa.

Which brings up the question: is there such a thing as a field guide
to insect galls? I've seen so many interesting and unusual galls in
the field, but have never come across a resource at identifying them.
I know this must be difficult, especially for those insect that may
gall more than a single species of plant, and the differences in gall
appearance between hosts.