Question
I have, in Ohio, what I believe is a red maple whose leaves are covered (underside along veins) with what literally looks like an alien life-form of some kind...lol! The veins are bright red, swollen, curled up. It is within the veins itself but looks parasitic. Any clues?

Thanks much.

Answer
These are gall wasps. The insect lays its eggs on the leaf and secretes a chemical that causes the leaf cells to produce these galls. Some are rounded, some are spindle shaped, some are long and pointed--many different shapes. Within a few days the galls are fully formed. The larvae feed within the protection of the gall until late summer. At this time the galls dry and a slit-like opening is formed. The mature larvae drop to the soil to seek shelter. Other than the mere aesthetic damage and possible early leaf drop, no significant damage is done to the health of maple trees. Following a mild winter, damage from these leaf galls can be excessive but affected trees often send out new leaves to replace the damaged ones.

Since these leaf galls of maple do not cause any real harm to the trees, control measures are not generally needed. No lasting damage will result.