INCIDENCE OF POPILLIA-JAPONICA (COLEOPTERA, SCARABAEIDAE) AND OTHER SCARAB LARVAE IN NURSERY FIELDS

Arborvitae (Thuja occidentalis 'Pyramidalis'), Colorado blue spruce (P icea pungens), taxus (Taxus x media 'Densiformis'), and dwarf burning bush (Euonymus alata 'Compacta') nursery fields in Ohio and Michigan w ere sampled for Japanese beetle, Popillia japonica Newman, adults and larvae. Nursery fields in counties with the highest adult catches were -the most likely to have larvae in the field. Nursery fields where <5, 000 beetles per trap were caught during 4 wk of peak activity were unl ikely to be infested with larvae (5 larvae in 3,120 cup-cutter samples ). Larvae were 4-fold more abundant in grassy areas bordering fields t han in nursery fields. Weedy nursery fields supported 10-fold more lar vae than clean fields. European chafer. Rhizotrogus majalis (Razoumows ky); Phlyllophaga sp.; and Strigoderma arboricola (Fab.) were also fou nd in nursery fields. S, arboricola larvae could be mistaken for Japan ese beetle because they have a similar rastral pattern. The labrum sho uld be examined to confirm identification of these 2 species. Nurserie s located in areas where Japanese beetles are active should keep field s as free of weeds as possible to minimize the risk of shipping larvae in the root system of nursery plants to states where Japanese beetle is not yet established.