Archive for Sunday, September 8, 2002

Attack of the fruit fly

September 8, 2002


The hot dry weather has not slowed the fall harvest. Many gardeners are still able to enjoy a vine-ripe tomato or cucumber.

Unfortunately, this late in the season when harvesting the produce fresh fruit is not all that is being brought into the home. An abundance of overripe fruit outdoors has led to a healthy population of the dreaded fruit fly indoors.

So if you are annoyed by the silent invaders, here are some tips to help you win the battle against these two-winged pests.

Adult fruit flies are 1/8 of an inch long, are a tan-brown and usually have red eyes. They are strong fliers and can travel up to six miles in one day.

The adult females lay about 500 eggs on or near fermenting organic matter. Eggs hatch in as little as 24 hours and the larvae begin feeding near the surface of the fermenting food. Larvae feed for five or six days then pupate into adults. Adults mature and mate in two days and the next generation starts the process over. With this in mind, just a few fruit flies can become an out of control population in as little as two or three weeks.

Sanitation is the most efficient method of controlling fruit flies. Simply eliminate all over ripe fruit and uneaten portions of food. All exposed fruits and vegetables not consumed immediately should be refrigerated before fermentation begins.

But it does not stop there. Fruit flies can also breed in drains, garbage disposals, fruit juice spills under the refrigerator, empty bottles and cans in recycle bins, unclean trash containers, mops and cleaning rags. All that is needed for development is a moist film of fermenting material. Therefor, extend your cleaning efforts to these areas as well.

Potential breeding sites such as garbage disposals and drains can be inspected by taping a clear plastic food storage bag over the opening overnight. If flies are breeding in these areas, the adults will emerge and be caught in the bag.

After the source of attraction and breeding is eliminated, a pyrethrum-based aerosol insecticide may be used to kill any remaining adult flies in the area.

Likewise, the use of traps can catch adults as well.

To construct a trap, place a paper funnel rolled from a piece of notebook paper into a jar that has been baited with a few ounces of cider vinegar. Place the jar trap wherever fruit flies are seen.

Alternatively, a Mason jar with black paint or paper to cover the top third makes a good trap. Coat the inside of the jar with a sticky liquid such as diluted honey or vegetable oil. Invert the jar over a bait such as a crushed banana. Rest the jar upside down on two blocks of wood to allow flies space enough to feed on the bait.

After leaving the bait, they fly up to the light and rest on the sides of the jars and become stuck. Simply discard the used traps when all the adults have been captured.

Bruce Chladny is horticulture agent at K-State Research and Extension-Douglas County. For more information, call him at 843-7058 from 8 a.m. to 5 p.m. weekdays.

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