Last week I received a call from a frantic home gardener worried about her bitter melon. Her first crop was superb. But her latest attempt was turning out to be a disaster. Fruit flies managed to sting every fruit she had hanging on her trellis.

The grower purchased a bottle of methyl eugenol from the garden shop and was thrilled with the result: a bucket full of fruit flies. However, little did she know that the insects she caught were Oriental fruit flies, while the bitter melon-stinging culprit is the melon fly.

There are four major fruit flies in Hawai'i: the Oriental fruit fly, melon fly, Mediterranean fruit fly and the Malaysian fruit fly. Each fly has a different host range.

Each fly also is attracted to a different type of male lure, so be sure to use the correct attractant when making fruit-fly traps. The Oriental fruit flies are attracted to methyl eugenol, melon flies go for cuelure, Med flies prefer trimedlure or Biolure. Attractants are placed in a trap to lure male fruit flies. The combination of the attractant with a sticky card or soapy water results in the reduction of males in the population. This is referred to as the male-annihilation technique. Lowering the number of male flies will minimize the chances of successful reproduction and regeneration.

Keep in mind that traps alone cannot suppress fruit flies as they catch only male flies. Female fruit flies sting and damage fruits.

In my next article, I will address the key techniques to minimizing fruit-fly damage in your home garden. For more information about fruit flies, go to www.extento.hawaii.edu/fruitfly.