Catching pumpkin flies: get your timing right

Pumpkin flies can cause serious yield loss in cucurbits They are especially troublesome when the fruit is young and tender, warns Bill Kerr.

- Bill Kerr

An extremely damaging pest of cucurbits, probably known by anyone who grows these crops, is the pumpkin fly (Dacus spp). The fly is reddish-brown with a distinct yellow spot on the thorax where it joins the abdomen; it also has less distinct yellow spots on the sides of the thorax. There are five Dacus species in South Africa, which are not easily distinguished from one another. They are between 6mm and 10mm in length.

The flies seek out young fruit which still has a tender skin, but also attack older fruit if no young fruit is left. The fly inserts its tube-like ovipositor through the skin of the fruit and deposits a few eggs, which hatch in about two days. The larvae emerge from the fruit a week later to pupate in the soil.