Attack of the Killer Flea Beetles

Last week I discovered that many of my vegetable seedlings were under attack. The enemy - flea beetles. Once the enemy was identified, I had to plan a swift counter attack.

Flea beetle infestation on pea seedling

Flea beetles look like tiny specks on a plant (they are the tiny black specks in the photo above, but may also be lighter colored). You won't notice the pest from a distance, you'll probably notice the leaves of the infested plant are turning brown, or have spots on them. Take a closer look and enemy will become clear, you will see them crawling around. If you're still unsure it's flea beetles, just disturb the plant or surrounding soil and you'll know it when you see them jumping around.


After discovering the infestation, the first thing I did was post a message asking for advice on my Facebook page. Several people answered my call for help with great tips on things to try.  I also spent some time doing research on the internet.

My findings? Well, it seems there's not much you can do to eliminate flea beetles, you just have to control them long enough for the plant outgrow the damage. Flea beetles can kill seedlings in a short time, at minimum they will stunt the growth of immature plants. Once the plants are large enough, the beetle isn't as much of a worry.

I found several options for controlling my flea beetle infestation. Of these suggested control methods, I chose the ones I thought would be easy to try, and of course organic. I'm not using pesticides on my vegetables.

I've done several things to try to combat the pests, here's what I've tried so far...

Leaf mulch to (hopefully) control flea beetles

• Soapy water spray (which I use for houseplant pest infestations) - It kills them on contact, but has no residual effect. I have been trying to spray twice a day.

• Coffee grounds and crushed mint leaves - I sprinkled them on and around the seedlings in one area first and it seems like there are less flea beetles around those seedlings than the others I didn't treat. I don't have a ton of mint yet and now I'm out, but I plan to reapply coffee grounds after heavy rains.

• Compost - I have a raised bed that I filled with compost before planting, and those seedlings are unaffected. Not sure if it's because the flea beetles haven't found them yet or because of the compost. I may have to try surrounding my other crops with compost.

• Mulch - When I first discovered the flea beetle infestation, it seemed like they covered every inch of the soil. I've read mixed reviews about using mulch to control them, but it seems to have worked well for now, at least to slow them down. I used straw and leaves around some of the seedlings, and hardwood mulch around others.  

Straw mulch used to (hopefully) control flea beetles

Now, a week later, I feel like my efforts are starting to pay off and I am gaining ground on the pests. The peas seem to be growing fast now that I've been controlling the flea beetles. But the cole crops have been much slower to recover. I think I may need to initiate battle plan B.

What's battle plan B?

• Row covers - Originally I was going to try row covers, but once I saw that the flea beetles were everywhere in the soil, I figured row covers would be pointless. But now I think that if I put row covers on and continue to spray under the covers to kill what's there, maybe the ones that jump away won't be able to re-infest the seedlings. I'll have to find a very fine mesh fabric to keep these tiny pests out.

• Garlic and hot pepper spray - I read that this is a natural repellent for flea beetles. I don't think it's meant to kill them, but it has a residual effect to keep them away.

• Ladybugs - I buy ladybugs every year and release them in my gardens, but usually not until June. I think I'll head to Bachman's and see if they're selling them this early. (Praying to the ladybug gods.)

In the ten years I've lived here, I've never had a problem with flea beetles. I read that flea beetle infestations are worse after a mild winter; well, we had the mildest winter I ever remember, so now I know why they are so bad this spring.

What do you think? Anyone have any additional advice for me?