Pests: Three-Lined Potato Beetle (Lema daturaphila)
Pest/disease identification and lifecycle, most common damage symptoms and crops affected:
The favorite foods of the three-lined potato beetle are crop and weed species in the Physalis genus, notably tomatillo and husk cherries. Potatoes, tomatoes and eggplants are also sometimes attacked. The adult of this pest is about the same size as a cucumber beetle but has a reddish head and a thorax with two dark spots. Its wing covers are dark yellow with three black stripes. The three-lined potato beetle overwinters in the soil in the pupa or adult stage, and emerges in the spring. Females begin laying eggs between early June and early July, which hatch about two weeks after that. The larvae that emerge look a bit like Colorado potato beetle larvae, except these critters have the endearing practice of carrying a small pile of their own excrement on their back. The larval stage is where the most feeding damage occurs. The larvae mature in about two weeks. There are possibly two generations per year.
Management options:
Cultural:
On most crops, the damage from this pest does not warrant control. If three-lined potato beetle has been a problem in the past, floating row covers will help you exclude the overwintering generation from finding your crops and laying eggs, and that should get you by. Hand-picking into soapy water will work on small plantings. Removing solanaceous weeds, particularly species in the Physalis genus, will help to check their population growth by taking away alternative host plants.
Organic pesticides (as a last resort):
Pyrethrin (Pyganic) or spinosad (Entrust, or Monterey Garden Insect Spray for home gardeners) may offer some relief.
Informed by: Eric Sideman
