Life Cycle

Development from egg to adult under summer conditions requires from 12 to 28 days, according to the individual and to host and weather conditions. The developmental periods may be extended considerably by cool weather. The preoviposition period lasted 7 to 26 days and the oviposition period 39 to 95 days. A single hardy female may lay as many as 1,000 eggs. Eggs generally are laid in young fruit, although they are laid also in succulent stems of many host plants, in cavities made with the aid of a sharp ovipositor. Only ripe fruit of some hosts are attacked. Pupation normally occurs in the soil, usually beneath the host, at a depth of up to 2 inches. Adults may live more than a year. Adults feed primarily upon juices of host plants, nectar, and honeydew secreted by various kinds of insects. There may be as many as eight to 10 generations a year.

Nature of Damage

Larval feeding damage in fruits is the most damaging. Mature attacked fruits develop a water soaked appearance. Young fruits become distorted and usually drop. The larval tunnels provide entry points for bacteria and fungi that cause the fruit to rot. These maggots also attack young seedlings, succulent tap roots of watermelon, and stems and buds of host plants such as cucumber, squash and others.

The economic importance of the melon fly cannot be evaluated entirely from the standpoint of the direct damage to the various crops affected. Quarantine laws aimed at preventing the entry and establishment of melon flies in areas where it does not occur often reduces the export potential of locally grown crops.