The pickleworm (Diaphania nitidalis) is a serious agricultural pest insect in the Crambidae family. It damages squash primarily, but it is also a common pest of other cucurbits such as cucumbers and melons. It is a tropical species which can be found in the southern United States. It does not tolerate cold temperatures.
The pickleworm adult is a flashy moth with wide triangular wings and a wingspan of about one inch. The wings are mostly iridescent brown, with a central band of yellow and thin white borders. The legs are white. The abdomen is mostly brown except for the tail segment, which is white and has a large fluffy tuft. It lays tiny eggs in small clusters on growing areas of the plant, such as flowers, shoots, and new leaf buds. These areas are the feeding spots for the larvae, which emerge after a few days and eat voraciously for two weeks. The younger larvae are thin white caterpillars with numerous small black spots. As the larvae mature they become plump and darker in color, and they lose their spots. The larvae tuck themselves into crumpled dead leaves to pupate for 8 to 10 days. In warm areas the pickleworm can produce four generations per year.
Pickleworm damage on cucurbit crops is evidenced by the lack of flowers and new leaves and shoots, as these are the first parts of the plant to be consumed. The larvae also eat the fruit, burrowing down into the flesh and leaving a hole marked with a pile of white frass.