Grape Flea Beetle: A Sporadic Spring Pest

In the spring, small (3-5 mm) shiny blue beetles can sometimes be found feeding on developing grape buds. Because of its colour, the grape flea beetle (Altica chalybea) is also called "steely beetle"; its ability to jump impressive distances for such a small beetle is where the "flea" in its name comes from. The overwintered adults feed on grape buds or even hollow them out and this stage in the spring is generally the only one that causes any appreciable damage.

Grape flea beetle is normally a minor pest but it can cause significant damage in some cases if enough beetles are present. After buds are over 2 cm long, grape flea beetles usually do little damage; a cool spring with slowly developing vines allows more time for the beetles to cause damage. Monitoring as vines are getting started in the spring is important especially if an area has been infested by flea beetles in previous years. Vineyard edges near woods where alternate hosts for the beetle may be growing (wild grape and Virginia creeper) are prime areas for grape flea beetles. Abandoned vineyards can also be significant sources of this pest.

During their spring feeding, grape flea beetle females lay their eggs on the canes and later die. The larvae that emerge from those eggs feed on grape leaves but usually do not cause sufficient damage to warrant any control measures. However, if severe amounts of larval feeding are detected, a spot or border spray may be appropriate to help lower the local population. Most of the time though, it is only the spring feeding adult beetles that require any attention.

If grape buds are being eaten, but careful inspection reveals no grape flea beetles, there is the possibility that climbing cutworms are eating the buds. These larvae of Noctuid moths feed only at night, so return then with a flashlight and look for them on the vines.

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