Extension Communications
3614 Administrative Services Building
Ames, Iowa 50011-3614
(515) 294-9915
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Extension Communications |
11/19/03
Contacts:
Betsy Matos, Entomology, (515) 294-1999, bmatos@iastate.edu
Jean McGuire, Continuing Education and Communication Services, (515) 294-7033,
jmcguire@iastate.edu
Yard and Garden Column for the Week Beginning November 21, 2003
Tiny Bugs with a Strong Bite!
By Betsy Matos
Entomology Graduate Student
Iowa State University
Ouch! What is this black creature that is biting me?
While preparing your garden this fall, you may have experienced the nasty bite of a tiny, black insect. Some people may even have an allergic reaction. It may be hard to believe this insect is one of the good bugs called the minute pirate bug. Other common names are insidious flower bug and Orius, the genus of the scientific name used to identify this insect.
Minute pirate bugs get their name because of their size, a mere 1/10 of an inch long. These insects are oval to triangular in shape, somewhat flattened and black with whitish markings on the back.
The minute pirate bug is a predator of aphids, thrips, spider mites, caterpillars and other small arthropod pests. As a predator it eats several prey during its lifetime, and it is usually bigger in body size than the prey. Their mouthparts are needle-like, and they suck the juices out of their prey. When they cannot find prey, they will use nectar sources as supplement. There are several companies that sell minute pirate bugs for people to release in their gardens and greenhouses. When you encourage minute pirate bugs in your garden, you are practicing biological control. However, remember that if you use broad-spectrum insecticides, you may be killing these and other beneficial insects because most natural enemies are sensitive to insecticides.
Minute pirate bugs undergo an incomplete metamorphosis (no pupa stage) life cycle. The adult female lays single eggs within leaves and other plant tissues. Nymphs develop through five stages (instars) before becoming winged adults. All of these stages exhibit a predatory behavior. The life cycle takes approximately 3 weeks, thus several generations may occur each year. In the fall, adults migrate from vegetation toward overwintering sites such as leaf litter.
Minute pirate bugs are usually found in a variety of habitats because they depend on prey sources. Corn and soybean fields offer a wide variety of prey for these predators. However, if you look closely, you may see several stages of the minute pirate bug in your yard and garden, which offers an excellent habitat.
One assumption why minute pirate bugs were a nuisance this year could be related to environmental factors. Insects are dependent on temperature and day length to tell them when to go into or come out of overwintering. However, because there was a long dry period, many plants started to age and drop leaves earlier than usual, and the temperatures stayed warm. The available prey became scarce, and many minute pirate bugs searched everywhere for prey. In this search, the bugs tried feeding on humans. Although their bite is painful, they do not feed on human blood or inject venom.
Control of these bugs is not necessary, especially since this phenomenon is atypical and short-lived and these are beneficial insects. However, if you are allergic to their bite, you might want to avoid light-colored clothing (very attractive to these bugs) next fall. Deet-containing insect repellents are generally not effective.
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