- Author: Lee Oliphant
- Editor: Noni Todd
Green Spotted Beetles-Not Ladybugs
By Lee Oliphant UCCE Master Gardener
I've begun seeing insects in my garden that look like little green ladybugs. They're eating flower petals and leaves. What can I do to get rid of them? Carol G., Cambria
Except for its shape and size, the yellow-green western spotted cucumber beetle (Diabrotica undecimpunctata), is not related to the red “ladybug” or lady beetle (of “Fly Away Home” fame). The spotted cucumber beetle is a destructive insect that feeds on plants and crops, especially in cool coastal climates. Even its larva is considered a pest as they feed on the plant roots before taking to the air as adults.
Cucumber beetles are difficult to control without endangering coveted beneficial insects like bees, ladybeetles, parasitic wasps, and lacewings. They have few natural enemies except for the tachinid fly (a parasitic fly that lays its eggs in the beetle, eventually destroying it).
There ARE a few things you can do to lessen the impact these little insects have on your garden. Knowing its life cycle helps. The cucumber beetle overwinters in the soil around plant roots where it lays its eggs. Fall clean up and cultivating the soil around shrubs will help rid your garden of the hibernating beetles and its eggs, and will disturb root-chewing larvae. After the eggs hatch in early spring you must go into full attack to reduce the number of beetles and interrupt the life cycle.
- Patrol the garden in the early morning. Carry a small container of soapy water and knock cucumber beetles into the bucket. If you do this on a regular basis, you will be surprised with the results.
- Heavy mulching, 4” or more, may deter cucumber beetles from laying eggs in the ground.
- Cultivate ground around plants in the fall and spring to expose the eggs, but being careful not to damage plant roots.
It is not recommend that you spray insecticides to alleviate the spotted cucumber beetle. Insecticides will often do more harm than good by destroying beneficial insects. For more information on the cucumber beetle go to IPM Pest Notes at http://www.ipm.ucdavis.edu/PMG/r116300511.html or call the UCCE Master Gardener helpline if you have additional questions.