Banded Cucumber Beetle

This beetle is 5 to 6 millimeters long. It has a red head and black thorax. The elytra are yellow, marked with three transverse bands in shades of green or blue-green and a narrower longitudinal green line down the center. The pattern of banding is variable and nearly absent in some individuals. The color of the elytra is influenced by the types of plants the beetle eats. The larva is also variable and has three instars. The new larva is white and about 2.3 millimeters long. It may turn yellow as it consumes plant material. The later-instar larva may reach nearly 9 millimeters. The adult mates at about six days of age. The female begins producing eggs about 16 days later. She lays a cluster of eggs every few days for two to eight weeks, producing up to 15 clusters, for a maximum of 850 eggs. A cluster has up to 100 oval yellow eggs each about half a millimeter long. The female oviposits the cluster in a crack in the soil, and the eggs hatch in 5 to 9 days. The larva develops for 11 to 17 days, pupation takes 4 to 6 days, and the adult has an average life span of 26 days. There is no diapause. In the best conditions there can be six or seven generations per year. In Tamaulipas, Mexico, the beetle is most commonly observed in May through July. This may be a time of high dispersal. …

The beetle likely originated in the tropical Americas and has moved into more temperate climates. By the early 1900s it was limited to Arizona and Texas in the United States. During the 1920s it spread up the coast of California at a rate of about 25 miles per year. It has since spread as far as North Carolina and Florida. It probably will not progress farther in the continental United States because it does not tolerate freezing temperatures.

Natural enemies of the beetle include ants, which prey on its eggs, particularly in the tropics. A Heterorhabditis nematode isolated from the larva of this beetle has been demonstrated to be a parasite that causes rapid mortality. It is also a host to the tachinid fly parasitoid Celatoria compressa.