Something is eating what looks like jagged holes in the leaves of my vegetables. What can I do about this organically? CK

This time of year, there are a lot of insects out there feeding on our plants. One way to help identify the pest, if you are unable to find them, is to look at the type of damage they are doing. Insects leave clues about who they are by the type of damage they leave. Most of this has to do with which type of mouth parts they have.

Insect mouth parts can be grouped into three groups: piercing-sucking, chewing, and rasping. The damage you are describing would be attributed to chewing mouth parts. To narrow it down further we need to look at the type of chewing damage.

Are the edges of the chewing damage smooth and rounded or is the eaten area more jagged in shape? You indicated the damage was more jagged in appearance and this would indicate some type of beetle. If the chewing damage left a more rounded hole in the leaf, that would indicate the presence of a caterpillar. Now that you know this, you can better determine your plan of action.

First of all, you always have the option of doing nothing to diminish your beetle population. Not all gardeners can embrace this option, but it is a valid approach. If however, you don’t want to share your crop with others, you have some choices.

First up is hand picking or hand squashing. Just get your gloves on and get to work harvesting the beetles that are causing the problem. Likely you won’t get them all in one pass so you’ll have several beetle hunting safaris in your future.

It this is not your style; we have good organic pesticides such as Spinosad or Pyrethrin to help. Both of these will be effective against beetles, and they have a short “pre-harvest interval.” We have talked about this before, but a pre-harvest interval is the period of time between when you use the pesticide, and you can safely harvest your vegetables. Organic pesticides tend to have shorter pre-harvest intervals than do synthetics. So, read the label to make sure you understand how to use your pesticide safely.

Had the chewing damage been more circular in shape, it would probably have been caused by some type of caterpillar. Some of them more voracious and destructive caterpillars to take up residence on your vegetables would be the cabbage looper. Cabbage loopers are small, maybe 1/2 to 1 inch in length but don’t let their small size fool you, they can’t do some damage. Plus, if you see one, it’s guaranteed there are a lot more. Bacillus thuringiensis is a good organic pesticide to treat for cabbage loopers. One treatment is about all it takes but again, read the directions and follow the product instructions. Good luck.

You can get answers to all your gardening questions by calling the Tulsa Master Gardeners Help Line at 918-746-3701, dropping by our Diagnostic Center at 4116 E. 15th Street, or by emailing us at mg@tulsamastergardeners.org. Photo - Clemson University - USDA Cooperative Extension Slide Series , Bugwood.org