of the tree on bare ground. We placed one 

 unbaited pyramid trap next to the tree trunk 

 and one at the north edge of the canopy (when 

 releases were north) or south edge of the canopy 

 (when releases were south). 



Results revealed that about 20% of released 

 curculios were captured by the trap at the 

 trunk and about 4% by the trap at the edge of 

 the canopy, irrespective of where released. 

 Further results revealed that of all released 

 curculios, about 15% eventually flew into the 

 tree canopy, about 15% flew toward open space, 

 about 1% flew onto the tree trunk, about 2% 

 flew onto the trunk trap, and about 1% flew 

 onto the edge trap. Interestingly, about 40% of 

 released curculios crawled toward the tree 

 trunk, with no more than 4% crawling in any 

 other direction. This was true irrespective of 

 whether curculios were released north or south 

 of the tree trunk. 



These results support results reported in a 

 preceding article in this issue showing that 

 several times more curculios were captured by 

 pyramid traps next to tree trunks than by 

 pjrramid traps more distant from tree trunks. 

 Results here also indicate that when evening 

 temperatures are moderate (somewhat condu- 

 cive to flight but not highly so), only a very 

 small proportion of curculios that does fly 

 alights on pyramid traps. The great majority in 

 flight bypasses the traps. On the other hand, a 

 very high proportion of crawling curculios 

 moves toward the tree trunk, where they 

 encounter and ascend either the tree trunk or 

 an adjacent pyramid trap. 



Conclusions 



Perhaps the most important general 



conclusion from this array of studies is that 

 when temperature is high enough to permit 

 plum curculio flight, curculios may fly directly 

 into tree canopies (either from overwintering 

 sites or from ground beneath trees). In so 

 doing, it appears that most are likely to bypass 

 unbaited pyramid traps, irrespective of trap 

 location. Unbaited pyramid traps, especially 

 when located next to tree trunks, appear to be 

 very good at capturing curculios that are 

 crawling toward the greatest area of darkness 

 in the habitat (that is, toward the center of the 

 tree). Substantial numbers of curculios appear 

 to crawl toward tree trunks and adjacent 

 pjrramid traps when temperatures are too low 

 and/or the amount of light is too little to permit 

 flight. Hence, unbaited pyramid traps at tree 

 trunks may afford an accurate representation 

 of curculio populations in orchard trees during 

 periods that favor curculio arrival in trees by 

 crawling but not during periods that favor 

 curculio arrival in trees by flight. Overall, as 

 shown here, a band of Tangletrap around the 

 tree trunk is of little value in preventing 

 curculios from achieving substantial numbers 

 in tree canopies. 



Acknowledgments 



This work was supported by grants from the 

 USDA Northeast Regional IPM Competitive 

 Grants Program, the USDA SARE Program, 

 the New England Tree Fruit Growers Research 

 Committee, and State/Federal IPM funds. We 

 thank Jim Hardigg of South Deerfield, MA for 

 permission to work in his orchard. 



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Fruit Notes, Volume 62 (Number 1), Winter, 1997 



