Insect Quiz November, 2004

November Quiz 2004

As fall settles in, you reminisce about a strange insect you saw at the end of the summer. It was about one inch long with a dark-colored, stout body and long, conspicuous, clear wings. You found it clinging to the trunk of a tree but it didn’t seem to be feeding. The tree did not appear to be injured from this insect. You can’t decide if this insect looks more like a bug or a big fly.

QUESTIONS

1. What is this insect?

This is an annual (also called dog-day) cicada. Despite its appearance, it is not a big fly but is more closely related to a aphids, leafhoppers, treehoppers, spittlebugs, and mealybugs. Annual cicadas are active during the day. Males produce a loud sound that resembles the hum of a power line. Cicadas should not be confused with katydids which also sing a loud song but are active at night instead.

2. What is the life cycle of this insect?

Cicadas spend most of their life in the ground as immature nymphs where they feed on roots. Annual cicadas live as immature insects underground somewhere between four to eight years. Adults emerge in July and August and can be seen until the end of summer. There is enough overlap between different generation that we see cicadas every summer. Annual cicadas are closely related to periodical cicadas which live for 13 or 17 years (nearly all of that underground) and have synchronous mass emergences.

3. Is this insect harmful to trees?

Cicadas use piercing-sucking mouthparts to feed on plant fluids from twigs or they may not feed at all. Fortunately any feeding that may occur does not harm trees. However, they are more injurious when laying eggs. Females use a sharp, saw-like ovipositor (egg laying device) to insert their eggs under bark. This splinters the wood on young twigs usually resulting in their death. While some twigs may be killed, the health of trees are not at risk. Fortunately cicadas are not considered a landscape pest.

4. What is the best management for this insect?

This insect is harmless to people and has little impact on trees and should be ignored. No control is necessary when you encounter cicadas.