In addition flea beetles can cause growers serious problems on seedling radishes and Asian specialty crucifers such as bok choy, choy sum, yow choy, gai lan, gai choy, Nappa cabbage and pak choy. The flea beetle adults feed on the leaves of crucifer vegetables causing a 'shot-hole' type damage, which if severe enough, can kill or stunt young plants.
Seedlings are much more susceptible than transplants or mature plants.
The 'Integrated Crop Management' program for cole crops emphasizes first and foremost regular and consistent field monitoring. Flea beetles are easy to recognize, being small, shiny and very fast black or black and yellow striped beetles. They are about 3-4 mm long and jump off plants when disturbed. There are two predominate species in Ontario, the shiny, black, crucifer flea beetle and the black and yellow striped flea beetle. Both species feed on cole crop seedlings and cause similar types of damage.