Beetles in Red Potato and Tomato Plants

Asked July 23, 2014, 5:21 PM EDT

I have red potato and Tomato plants. There is a particulate beetle that is feasting away and destroying them. What is the beetle and how do I get rid of it to protect my plants. Thanks,

New Castle County Delaware

1 Response

The beetles eating your tomatoes and potatoes appear to be Colorado Potato beetles.

Colorado potato beetles are difficult to control. Hand removal and rotating insecticides are very important. Some beetles will tolerate the insecticide that is used against them. It takes some trial and error to find the best choice for your garden. While individual beetles are not resistant to all insecticides, scattered populations contain resistance to nearly every insecticide. Spraying insecticides will kill the susceptible ones. Continually spraying the same insecticide allows resistant beetles to flourish and can help develop resistance in others. It is therefore important to avoid repeated use of one particular insecticide. Other factors besides insecticide resistance can contribute to control failure. Timing of sprays is critical for control. Overwintering beetles are attracted to fields over a period of several weeks. Spraying an insecticide too early may only control a portion of those beetles. However, waiting until larvae are nearly full-grown also increases the chances of control failure. Small larvae are much easier to control with an insecticide than large ones. Using the correct amount of insecticide as well as obtaining complete coverage of the plants is very important. Insecticides should only be used when needed. Generally, insecticides do not need to be applied unless there is more than an average of one beetle or larva per plant. Additionally, some beneficial insects such as birds, predatory stink bugs, and parasitic flies will help to reduce Colorado potato beetle numbers.

Good options for small gardens include crop rotation and hand picking. Look on the underside of the leaves for egg masses and remove before they hatch. See photos of the egg masses in the fact sheet included below. Remember that use of insecticides will harm beneficial insects including pollinators and those that help with potato beetle control.

For comprehensive information about Colorado potato beetles and their control, and pictures of the beetles at various life stages see: