I have a small outbreak of flea beetles which are destroying my mixed lettuces and appear to be discovering my eggplant transplants in the greenhouse. I read that Bt can be used for flea beetles. Do you know which type? Diatomaceous earth is not helping, soapy water is not helping and I feel like it is too late to use row cover at this point. What are the health risks to humans if I use Bt? Is it considered organic? Also, has anyone tried using beneficial nematodes to get rid of flea beetles?
The first step to make sure that the problem is indeed caused by the flea beetle. It sounds like you have had the insect identified? A couple of notes: Bt is not a recommended control for flea beetles. (This bacteria is only effective on certain insects.)
- Diatomaceous earth works best in dry conditions, so our rainy spring will reduce effectiveness. That's one reason it may not have worked so well in your situation.
- There has been some research on using nematodes to control flea beetles (the immature stage, not the adults) however, I'm not sure what is commercially available or how effective it is a control.
You may see vacuuming to physically remove the insects as a control option. It can very effective but may be difficult to accomplish on a large planting or with delicate plants. If you decide to apply a product, make sure that both the plant and the insect are on the label and follow directions very carefully since this is a plant you will be eating. Good Luck!