Plum Curculio - Conotrachelus nenuphar (Herbst)

Dr. D. L. Horton, Professor and Extension Entomologist, The University of Georgia, Department of Entomology, Athens, GA 30602,
Dr. H C Ellis, Professor and Extension Entomologist, The University of Georgia, Department of Entomology, Tifton, GA 31793

In: Roberts, P. M. and G. K. Douce, Coordinators. 1999. Weevils and Borers. A County Agent's Guide to Insects Important to Agriculture in Georgia. Univ. of GA, Col. Ag. Env. Sci., Coop. Ext. Serv., Tifton, GA USA. Winter School Top Fifty Agricultural Insect Pests and Their Damage Sessions, Rock Eagle 4-H Ctr., Jan. 20, 1999.

Order Coleoptera: Family Curculionidae

Description: Adults are small brownish-black snout beetles, 4 to 6 mm long, mottled with lighter gray or brown markings. Snouts are slightly curved and about 1/4 the length of the body. Their backs are roughened and have two prominent humps and two smaller humps. Larvae are slightly curved, yellowish-white, legless, brown-headed grubs, about 6 to 9 mm long. Hosts: Plums, peaches, apples, pears, blueberries and other fruits Damage: Both adults and larvae cause damage. Adults damage fruit when their feeding and egg-laying causes scarred and malformed fruit. Adult damage also provides entry sites for fungal rots. Larvae tunnel and feed inside developing fruit. Most fruit infested early in the season drop prematurely. Fruit infested later in the season are of no market value due to the presence of the grubs.

Plum Curculio adult Photo by Clemson Univ./USDA Slide Series

Plum Curculio larva Photo Obtained from Entomology/Plant Pathology Workshop slide exchange, photographer unknown

Life Cycle: Adults overwinter in ground litter or other protected places. They become active shortly before peaches bloom. Adults fly to trees, mate, and lay eggs. Females deposit each egg in a hole under a crescent-shaped cut eaten in the fruit. Eggs hatch in about five days. Grubs feed in the fruit for eight to 22 days. Mature larvae tunnel out of the fruit, enter the soil, construct small earthen cells and pupate after about two weeks. The complete life cycle, from egg to emerged adult, may require five to eight weeks. There are usually two generations and possibly a partial third generation each year.

Control: Controls should be aimed at overwintering adults to prevent the laying of first generation eggs. Adults can be monitored by traps or limb jarring over a ground sheet. Sprays for curculio should be initiated at petal fall with the initial application followed by two or three sprays at 10-day intervals. Additional applications may be necessary for the second generation (ca. June). Destruction of nearby wild plums, abandoned fruit trees and other alternate host plants can help to reduce infestations

Updated from: Horton, D. L. and H C Ellis, 1997. Weevils and Borers. In: Hudson, R. D. and D. B. Adams. 1997. A County Agent's Guide to Insects Important to Agriculture in Georgia. Entomology 97, RDH (1). Univ. of GA, Col. Ag. Env. Sci, Coop. Ext. Serv., Tifton, GA 31793.

Selected References and Suggested Readings