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time when the adults arrive on the trees. Eggs hatch in about a 

 week. Larvae then tunnel into, and feed on, the developing fruits 

 for the next two to three weeks. Most of the larval-infested 

 fruits drop to the ground, and there the larvae leave the fruits 

 to pupate in the soil. Adult curculios emerge from the soil approx- 

 imately one month after that. These emerging adults feed on late 

 apple varieties or leaves and then overwinter, unmated, in or near 

 orchards. There is only one generation of curculios in Massachusetts. 



Damage caused by the plum curculio is of several different 

 types. Early in the season, curculios feed on and lay eggs in 

 young fruits. These fruits are then scarred with surface wounds. 

 Small round holes are the result of feeding punctures, while cres- 

 cent-shaped yellowish scabs are the result of egg-laying activities. 

 The most important injury is larval tunneling inside the fruits and 

 the correspondent fruit drop. Feeding scars of the adults in the 

 fall and adult feeding damage on blossoms in the spring are other 

 types of injury. 



Controlling this pest has been a frequently difficult as well 

 as expensive task, even with modern insecticide sprays. Research- 

 ers in other states are working on alternatives to chemical con- 

 trol of the plum curculio, but to date no practical means of con- 

 trol other than insecticides have been developed. A reduction in 

 the number of chemical sprays against the curculio would not only 

 save growers' money, but in addition would postpone the onset of 

 possible pesticide resistance, and decrease pesticide contamination 

 in the environment. Beneficial insects such as pollinators, preda- 

 tors, and parasites would also undoubtedly benefit from reduced 

 numbers of insecticide sprays. 



One of the purposes of our plum curculio project here in the 

 Department of Entomology is to study the activities of the adults 

 to determine whether there is any behavioral trait which could be 

 used in the development of a curculio trap. Although some aspects 

 of the biology and life cycle of the curculio are reasonably well 

 understood, there is little information on its behavior. A trap- 

 ping device such as is used for apple maggot or lepidopterous 

 pests (for example, the codling moth) would (coupled with informa- 

 tion on how many curculios an orchard could tolerate without affect- 

 ing crop quality or yield) aid the grower in determining whether 

 and when he should use insecticides against the curculio. It also 

 is possible that such a trapping device could be used as a direct 

 control measure -- that is, the trap itself could be effective in 

 controlling adult curculios, especially where only small popula- 

 tions were present. 



The major study that was conducted last summer involved spend- 

 ing many hours observing the behavior of adult curculios on apple 

 and plum trees located on Orchard Hill on the UMass campus. The 

 purpose of this study was to obtain some understanding of the cur- 



