How to Manage Pests
UC Pest Management Guidelines
Also known as picnic beetles, adult sap beetles are about ¼ inch (6.5 mm) in length, shiny black, and have four yellow-to-orange spots on the back of each wing cover. The tips of the antennae of both species are distinctively knobbed.
Sap beetles overwinter as adults in decomposing organic matter and emerge to resume feeding after a warming trend of temperatures over 68°F. While there is only generation of sap beetles per year, populations tend to peak by midsummer. Adults bore into caneberry fruit and can be contaminants in harvested fruit. Larvae, which are not often found on the inside of fruit, are about the same length as adults, with a brown head capsule.
Adult beetles bore into ripe to overripe fruit to feed and are often found around the receptacle. The feeding, while quite damaging, also can create entry pathways for fungi and bacteria, resulting in increased incidence of fruit rots.
Chemical control of sap beetles in caneberry fruit is very difficult, because applications to ripe fruit not only take place necessarily close to harvest, but also the beetles are inside the fruit, making them almost impossible to reach with conventional topical pesticide applications.
Organically Acceptable Methods
UC IPM Pest Management Guidelines: Caneberries