species of maples (Acer) show odd shaped galls and
blotches on their leaves. These sometimes velvety
textured or spindle-like growths are caused by tiny
critters called eriophyd mites.
There are several
different species which cause different types of
growths. These include the maple bladder mite, maple
spindle gall mite and some erineum gall mites.
The most common maples
infested include silver maples (Acer
saccharinum) and red maple (Acer
As with most gall forming
insects, they feed on the leaf tissue and many lay their
eggs in the leaf. These activities result in the plant
responding by creating a gall which is somewhat
equivalent to a tumor in an animal.
Erineum galls are those
that look like a patch of reddish velvet or felt
material on the bottom of maple leaves.