I not really sure why I find galls of all types so fascinating, but whenever I find one I’m always taking pictures of it. So be forewarned as the season gets under way, you’ll might be seeing more.
The picture above is a horned oak gall on a pin oak and as ugly as it is it is pretty cool and the fact the a tiny a cynipid wasp created it, is amazing.

“Horned galls Callirhytis cornigera, are abnormal growths or swellings comprised of plant tissue found on leaves, twigs, or branches. These deformities are caused by a tiny, non-stinging, wasp which produces a chemical or stimuli inducing the plant to produce large, woody twig galls. Most galls are aesthetically not pretty, but normally cause little damage to tree. However, severe infections may bring about the decline of the tree. Chemical control is seldom suggested for management.
Life cycle
“In early spring a tiny wasp of the cynipidae family emerge from woody stem galls. The females lay eggs on the veins of the oak leaf buds. Male and female wasps emerge from these tiny, blister type galls on the leaf vein about mid summer. Mated females deposit eggs in young oak twigs. The next spring small swellings develop on the twigs and enlarge over the next two or three years. The galls provide protection, food, and shelter for the developing larvae. When the larvae reach maturity, the horned galls developed small spines or horns. An adult wasp emerges from each horn and another life cycle of wasps begins.”