08/06/2026
It's that time of year again, and we're getting tons of questions about flea beetles on brassicas (and for a few unlucky folks, potatoes). Here are a few things to keep in mind
1. Trap cropping - This will only work if you destroy the trap crop somehow (tilling, spraying, crushing bugs). Planting nasturtiums or other flea beetle attractive plant and leaving them will likely not help, and may ramp your flea beetle populations up and draw more to your garden. Trapping cropping can be useful, but you should destroy the trap crop and the beetles on it for it to be most effective. If you want a companion plant that actually might help repel flea beetles from your veggies, use something like marigolds.
2. Neem oil- Neem is a useful insecticide, but it is not going to be very effective against a severe flea beetle infestation. It works best against soft bodied insects, and used prophylactically before infestations get completely out of hand. It can help as part of a flea beetle management plan but should not be relied on as the only line of defense.
3. Diatomaceous earth can be effective at reducing flea beetle feeding, but is probably not going to eliminate your infestation. Only applying it to the soil will not help much if at all, apply it to the foliage as much as you can. You will probably have to keep reapplying it frequently
4. The most effective non-spray method for protecting your plants is row covers. These must be fine mesh and installed at planting, and the edges buried to prevent any entry points. You want a mesh size of .35 mm or less to prevent flea beetles from accessing crops. If there are already flea beetles in the soil, the row covers will not work- make sure you rotate where you plant your flea beetle affected plants from last year.
4. Pyrethrin and spinosad based insecticides are going to be the most effective for the home gardener. Make sure you spray underneath leaves where flea beetles (and other brassica pests) like to hang out. Always read and follow the label.
5. Canola, many people say the flea beetles show up when the canola is cut. This simply is not true, the flea beetles are here and pretty much nobody is harvesting canola right now and won't be until towards the end of the month. It is difficult to tell where pests originate from, some of the beetles are likely coming from within your garden.
6. Host breadth- Crucifer flea beetles generally feed on vegetables in the mustard family, while potato flea beetles prefer the nightshade family. Neither will generally affect fruit trees or other landscape plants
Learn more about flea beetle management here-https://agresearch.montana.edu/wtarc/producerinfo/entomology-insect-ecology/CanolaFleaBeetles/OganicManagement.pdf
