April 2009. From Lihir Island, Papua New Guinea. Efforts are being made to grow fresh produce, such as lettuce, tomatoes, cucumbers, etc. Many of the plants are being eaten by a small orange beetle (photo attached), and control methods.
The beetle was identified as Aulacophora a leaf beetle (Chrysomelidae) – there is a species complex in New Guinea. In Guam, it is a pest of cucumber, but does not attack lettuce or tomatoes. A similis makes circular shaped cuts in leaves which do not’t seem to affect fruit yield very much. However, the grubs are root feeders and can kill plants if they occur in high numbers. This sometimes happens when cucurbits are planted in succession without rotation with a nonhost crop.
For a small garden, walk around early in the morning and pick them off the leaves and kill them. They are much less active in the morning than later in the day, when they can be difficult to catch. Obviously, this will not work for a larger farm, unless you have lots of workers.
The beetle was said to be a major pest in the Commonwealth of the Northern Marianas islands, where it is known as the Cucumber beetle (A similis).
The common name of Pumpkin beetle was also mentioned, and the scientific name Aulacophora foveicollis. Adult beetles feed extensively on the leaves, flowers and fruits. the grub bores into roots, stem and also fruits which lie on ground. Field sanitation, collection and destruction of beetles, and use of any contact insecticides if attack is severe, will give control.