Insect Quiz July, 2005

July Quiz 2005

One morning, you are walking around in your yard when you happen to look at the side of your house near your back door.  You see a large winged brown insect.  You aren’t sure where it came from but you only see the one insect.

1.  What is this insect?

This is a dobsonfly, an insect related to lacewings, antlions, and other net-winged insects (order Neuroptera).  A dobsonfly has a body length of 1 1/2 to 2 inches long.  They also possess long wings with many veins that extend well past its body.  Dobsonflies also have long filamentous antennae and conspicuous mandibles.  Males, in fact, have long, curved tusk-like jaws that can measure up to 3/4 inch long, making them look quite fierce and dangerous.  Dobsonflies are not know to feed.

2.  Where did the insect come from?

Dobsonflies are often associated with water.  Immature dobsonflies, known as hellgrammites, are found amongst rocks in fast moving streams and rivers where they feed on other insects.  Hellgrammites are known to fisherman as they sometimes use these insects as fish bait.  Once they mature, hellgrammites emerge from the water to pupate and then later emerge as adults.  They are attracted to lights and can be found away from water, although they are not strong fliers.

3.  Are they dangerous to people?

Ironically, although the males have the largest mandibles between the two genders, they use their jaws for mating and they would not be strong enough to hurt people.  The females are not aggressive towards people, although they are capable of administering a painful bite if they are handled carelessly.  Otherwise dobsonflies are harmless.

4.  What should you do if you encounter this insect?

A dobsonfly is just a curiosity and no control is necessary.  Just ignore it and it will go away on its own.