Trap capture 

 Fruit scars 

 Both 



ceive the trap as being the visual 

 equivalent of the trunk of a pecan 

 tree (Tedders and Wood, 1994). 



To date, unbaited Tedders 

 traps have been examined for 

 monitoring PC adults in Georgia 

 (Mizell et al., 1995) and Vermont 

 (Schmitt and Berkett, 1995). In 

 the Georgia study, substantial 

 numbers of PCs were captured in 

 unbaited Tedders traps placed on 

 herbicide-treated ground between 

 peach trees, but no comparison 

 was made between first detection 

 of PCs in the traps and first de- 

 tection of PC feeding or egglajdng 

 activity in the trees. In the Ver- 

 mont study, Tedders traps were 

 placed on the ground cover be- 

 tween trees in rows of Mcintosh or Liberty apples 

 in an experimental orchard. In one of the ten plots, 

 a PC was captured in a trap before any oviposition 

 was observed, and in one other plot, captures and 

 oviposition coincided in time; but in eight plots, ovi- 

 position occurred before trap capture (or there was 

 no trap capture). 



We repeated the Vermont study under Massa- 

 chusetts commercial orchard conditions. In addi- 

 tion, we conducted several experiments aimed at 

 finding out how PCs arrive at a Tedders trap (by 

 flying or crawling to it) and factors influencing the 

 probability of arrival. 



Experiments and Results 



Trap Effectiveness in Commercial Or- 

 chards. In each of 10 Massachusetts commercial 

 apple orchard blocks, one Tedders trap was placed 

 on the ground between two apple trees, within the 

 tree row. From petal fall until 3 weeks afterward, 

 data were collected weekly on trap captures of PCs 

 and evidence of PC injury to developing fruit in 5- 

 10 trees nearest the trap. The results (Table 1) were 

 very similar to results obtained in the Vermont study 

 by Schmitt and Berkett ( 1995). In one orchard, first 

 evidence of PC activity was capture in a trap. In 

 six orchards, first evidence of PC activity was feed- 

 ing or egglaying scars in fruit. In three orchards, 

 trap captures and fruit scars coincided in time. 

 These data suggest that information from a single 

 unbaited Tedders trap per 5-10 trees would not be a 

 reliable indicator of the need for insecticide appli- 

 cation to control PC. 



Means of PC Arrival at Traps. We carried 



Table 1. First post-bloom evidence of plum curculio activity 

 in apple orchards in Vermont and Massachusetts as 

 determined by capture of adults in a Tedders trap or feeding 

 or egglaying scars on fruit of 5 trees (Vermont) or 5-10 trees 

 (Massachusetts) nearest the trap. 



Numbers of Sites 



First evidenceof activity 



Vermont* 



Massachusetts 



1 

 8 

 1 



1 

 6 



3 



*Data from Schmitt and Berkett (1995) 



out two experiments to determine whether PCs ar- 

 rive at unbaited Tedders traps by flying or crawl- 

 ing. 



In the first experiment, conducted during the 

 last two weeks of June, four traps were placed in 

 short grass ( 1 inch tall) half-way between the trunks 

 and perimeters of each two large (standard root- 

 stock) unsprayed Mcintosh trees. Every other trap 

 received a thick coating of tangletrap at the base to 

 prevent PCs from crawling onto the trap. Trap po- 

 sitions were reversed after the first week. All 16 

 PCs captured were found in those traps without 

 sticky. None (significantly fewer) were found in the 

 traps with sticky. These data suggest that when 

 Tedders traps are placed beneath Massachusetts 

 apple trees whose canopies are large and whose 

 understory is short grass, responding PCs are likely 

 to arrive at the trap surface by crawling and not by 

 flight. 



In the second experiment, conducted during the 

 first two weeks of July, field-collected PC adults were 

 released at different distances from Tedders traps 

 in a large open field of short grass (1-3 inches tall). 

 On each of five evenings about 2 hours before dark 

 (when PC adults begin to become particularly ac- 

 tive), an opened waxed paper cup containing 55 PCs 

 was placed half-way between two traps, whose dis- 

 tances from the cup were either 2, 4, or 6 yards. On 

 each test evening, the temperature was about 75"F 

 at time of release. 



The results (Table 2) show that irrespective of 

 trap distance from point of PC release, only 3-47r of 

 released PCs were captured in traps (there was no 

 significant effect of distance). Of those PCs whose 

 flight after take-off was tracked by the observers 



fruit Notes, Winter, 1996 



