Colorado Potato Beetle

• Rounded, yellow-orange beetles with ten black stripes feeding on foliage
• Orange egg masses on the underside of leaves
• Soft, reddish-orange larvae chewing leaves from edges inward
• Heavy defoliation — plants can be stripped to bare stems
• Frass accumulates in the area where larvae cluster

Adults overwinter in the soil, emerging in spring when the soil warms to around 50°F. They begin feeding and laying orange egg masses on host plant leaf undersides. Larvae go through four instars and are most damaging in their later stages. Pupation occurs in the soil; a second generation of adults may appear in late summer. Colorado potato beetles are notorious for developing resistance to many insecticides.

1. 01Inspect plants every few days from emergence — egg masses are easy to see and crush
2. 02Hand-pick adults and larvae; they fall when disturbed, so hold a container under the branch
3. 03Apply Bt var. tenebrionis (Btt) — a strain specific to beetle larvae — while larvae are small
4. 04Spinosad is effective against larvae and has a shorter window of resistance development than synthetic insecticides
5. 05Rotate solanaceous crops to a different bed each year — adults emerging from soil won't find their host plant
6. 06Mulch heavily around plants to impede adult emergence from pupation

If control measures that worked in previous seasons are suddenly less effective, resistance may be developing. An extension entomologist can recommend rotation of modes of action and confirm which products are still effective in your region.

• Colorado Potato Beetle— University of New Hampshire Extension
• Colorado Potato Beetle Management— Penn State Extension