7 - 



culios' behavior. Observations were made at varying time intervals 

 from 8:00 A.M. to 9:00 P.M. on warm, sunny days. Once we had lo- 

 cated a curculio we watched that insect until it moved out of sight, 



From these observations, we found that the main activities 

 of adult curculios were: 



1. Exploration - moving about a tree in search of food, 



ovipositional or resting sites. 



2. Defense or camouflage behavior (These insects are very 

 sensitive to noises or other disturbances.) 



3. Resting 



4. Feeding 



5. Ovipositing (egg-laying) 



An adult curculio appears to have little recognition of places 

 it or other curculios had previously visited, as individuals spent 

 considerable time re-exploring the same areas. Curculios were 

 rarely observed flying, spending most of their exploratory time 

 crawling. It appeared that they were able to distinguish fruits 

 from twigs and foliage only upon direct contact, and not by dis- 

 tance vision or smell. In terms of egg laying behavior, females 

 spent several moments "drumming" their antennae and tarsi (feet) 

 on the fruit before they would attempt to lay eggs. 



These observations would suggest that curculio behavior is 

 rather complex, and for this reason it will take considerable time 

 to discover what methods curculios use to find their host trees, 

 food and mates. It appears that this insect has comparatively 

 little dependence on vision. For this reason, we doubt that a 

 trap employing only visual stimuli would be very effective. Also, 

 since within-tree flight appears to be of minor importance, traps 

 aiming to capture curculios flying within trees would likewise 

 probably not be very effective. Traps based on insect flight to 

 visual stimuli are relatively easy and quick to develop and use, 

 and we have indeed experienced some success with such traps for 

 tarnished plant bug, sawfly and apple maggot. 



We are closer to an understanding of plum curculio behavior 

 than we were a year ago. However, many further long term studies 

 on the behavior of adult plum curculios will have to be carried 

 out to uncover some behavioral trait which would lend itself to 

 an effective, efficient and reliable trapping device. 



