Flea beetles can be very destructive to a wide variety of plants, so be sure to take preventative measures.
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How to Identify Flea Beetles on Plants
Given that there are so many species of flea beetles, they vary in appearance quite a bit. Colors range from black to tan, with other, brighter colors mixed in, and the beetles may have a solid, striped, or spotted pattern, depending on the species.
To identify flea beetles, it’s easier to look for signs of their damage (described below) than for the beetles themselves. At only 1/16 of an inch in length, flea beetles are very tiny and will quickly spring away—like fleas—if they see you approach!
When Do Flea Beetles Appear?
Adult flea beetles overwinter in brush and wooded areas. Adult bugs pose the biggest threat early in the planting season as they are emerging, typically when outdoor temperatures reach 50ºF (10°C). At this time, seedlings are being planted, too, and they are most susceptible to beetle damage.
Eggs are laid at the base of plant stems in early summer after the spring feeding period, and larvae feed at the roots.
What Flea Beetle Damage Looks Like
Adult beetles feed on foliage, producing “shotholes” in the leaves. Look out for these holes, especially on young seedlings, where damage is most rapid and will cause the most harm. The holes they make will be round and can quickly ruin leafy greens. New leaves are usually damaged first and will have a lacy appearance.
Flea beetles usually don’t cause fatal damage to established plants because the leaves are already large enough to survive a few holes. The real danger is that the beetles can spread bacterial diseases, such as wilt and blight, from plant to plant. Additionally, in leafy crops like lettuce or spinach, the holes can bring down the quality of the leaves. Therefore, they are still important to consider as pests.
Catherine Boeckmann
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Do you have any suggestions for eradicating flea beetle indoors? I am a florist who uses locally grown flowers and these bugs seem to have setup camp in the drop ceiling of my studio. Not sure what they are surviving on.
I sprayed one leaf with the alcohol/water/liquid mixture yesterday. The leaf turned brown and curled. Any other ideas? Maybe less alcohol?
Yes, dilute the mixture with more water. Try doubling the amount of water and testing again.
My alder trees get these guys every year. I tried to wrap fly paper around the trunks this year and it appears to have helped a bit, but do they fly up from the ground into the upper areas of the trees or do they migrate up the trunks into the leaves? If they travel up the trunk, sticky tape would seem to be a possibility for controlling them. Any ideas? I lost an ancient singleton alder years ago from these bugs. If left alone, they can do significant damage.
We turned to the experts for help with this one, Roderineo, especially because you have them in your trees. Because the fleas seem to overwinter in the leaf and plant residue at the base of the trees (see the following), you might consider cleaning up those areas.
• Here’s a forest management site that describes their life cycle: https://www.fs.usda.gov/Internet/FSE_DOCUMENTS/stelprdb5186816.pdf
• Here’s the Oregon Cooperative Extension: http://oregonstate.edu/dept/nurspest/alder%20flea%20beetle.htm
• Britain’s Royal Horticultural Society has very good information; here’s what they say about this: https://www.rhs.org.uk/advice/profile?PID=850
We hope this helps!
what is it when I grow turnip the get holes all through them underground in the little turnips ive never seen any bugs could it be cutworms and how do I get rid of them?
Hi, Ken, It could be cabbage maggots, which are the larvae of the cabbage root fly. They love turnips. The most efficient preventative is to use floating row cover (light-weight “cloth”) in such a way that it creates a tunnel and is secued at ground level on all sides (and ends). The cover can touch the plants, but should be loose enough as to not constrict growth of the plant. We hope this helps!
I'm not sure that I have flea beetles because they don't try to jump away (or flee.. yuk) when pulled off my tomato plants. They tend to cling to the leaf. They are dark black, a tad shiny and shaped like a football with a somewhat rounded tail and a bit more pointed head. They are very small, 1/16" or smaller. They do have wings, small antenna and appear to have eight legs. Aside from that, they eat small elongated holes in the leaf and may have been responsible for yellowing of the plant especially on the bottom 1/4 of the plant. However, plant food seems to have helped with the yellowing. I applied Sevin spray this morning and hope that helps. Are these flea beetle and what else can I try if the spray doesn't help?
How large are the "parts" of alcohol and water? You specify 1 Tablespoon liquid soap, but not the amount of alcohol and water to which it is added.
You’re right, Linda. It seems we’ve mixed apples and oranges here. We suggest mixing 5 cups water with 2 cups alcohol plus 1 tablespoon of liquid soap.
