Key Features
- Leaves skeletonized
- Flowers chewed
- Copper and green beetles
Symptoms
Leaves and flowers are skeletonized when adult beetles remove plant tissue. When feeding on leaves, the tissue is removed between leaf veins. Adults have copper colored wings that are positioned behind their green heads. Adults can be found during the day feeding singly or in large groups on leaves or flowers.
Biology
Adult beetles emerge from the soil in mid- June to feed on leaves, flowers, and fruit of a wide variety of plants. They continue to fly for about 8-12 weeks, with the peak activity occurring from mid June through mid July. Eggs, laid underground in turfgrass hatch into small c-shaped white grubs during the first week of August. White grubs feed on roots of turf until weather cools in October when they move further down into the soil where they spend the winter. Grubs resume feeding on turf roots in spring until they go through a non-feeding stage (pupa) before turning into adults that emerge from the soil in June.
Management Recommendations
To reduce damage to leaves, flowers and fruits implement your control tactics when adults are numerous. Hand picking of adults and killing them by dropping them into a bucket of soapy water can be when trees are small and if you have time to spare. When beetles are too numerous to remove apply a broad spectrum insecticide, such as liquid carbaryl to leaves when beetles are seen feeding on trees. Apply these products after mixing with water according to directions on the pesticide label. Most materials will only kill beetles for 4 to 5 days. Pyrethroids like bifenthrin provide longer control up to 10 days. Chlorantraniliprole (Acelepryn) is a new product that will kill Japanese beetles up to a month without harming bees. To protect bees do not apply other products when plants are flowering. An alternative approach is to apply azadirachtin or neem oil to repel beetles. This works best before beetles have begun feeding in large numbers on plants.Consider using resistant varieties of crabapples when choosing new planting or plants not attacked by adults. Do not use Japanese beetle traps to control these beetles. Traps bring more beetles and damage to the area.
Effective Pesticides
Active Ingredients include: Acetamiprid, Azadirachtin, Bifenthrin, Carbaryl, Cyfluthrin, Lambda- cyhalothrin, Permethrin, Resmethrin
