for at least 6 yards, only 8, 4, and 0% respectively, 

 landed on traps 2, 4, and 6 yards away (Table 1). 

 PCs were observed to climb to tips of nearby blades 

 of grass, take off and fly in various directions. Sev- 

 eral were noticed passing within a yard or less of a 

 trap without landing. These data suggest that in a 

 field of short grass (possibly equivalent to space 

 between adjacent apple trees), only a very small 

 proportion of the PCs present is likely to arrive at a 

 Tedders trap two or more yards away, even when 

 environmental conditions are quite favorable for PC 

 activity. Some of these may arrive by flying onto 

 the traps, others probably by crawling. 



Factors Influencing Arrival at Traps. We 

 studied the influence of two factors on the likeli- 

 hood of capturing PCs in unbailed Tedders traps: 

 height of vegetation and presence of fallen fruit in 

 the vicinity of traps. Each factor was studied over 

 a 2-week period from mid-August to mid-Septem- 

 ber and involved assessing responses of newly 

 emerged PC adults that originated from larvae 

 which infested fruit in June. 



In the first experiment, four traps were placed 

 in short grass (1 inch tall) that comprised the ground 

 cover beneath half of the canopy of each of two 

 unsprayed Mcintosh trees. Another four traps were 

 placed in tall broadleaf vegetation (1 foot tall) that 

 comprised the remaining half of the ground cover 

 beneath the tree canopies. All fallen apples within 

 1 yard of each trap were removed. After 2 weeks, 9 

 PCs were caught in the traps in the short grass com- 

 pared with 8 PCs in the traps in the tall broadleaf 

 vegetation (no significant difference). These data 

 suggest that as long as ground cover vegetation of 

 some sort is present beneath the tree canopy, the 

 height of vegetation (up to 1 foot) may have little 

 effect on PC response to traps. 



In the second experiment, eight traps were 

 placed in 1-foot-tall vegetation beneath the two 

 Mcintosh trees. Every other trap received 30 re- 

 cently fallen Mcintosh apples placed within 1 yard 

 of the base of the trap. The remaining traps were 

 kept clear of all apples within 1 yard. Treatment 

 positions were reversed after 1 week. In all, 22 PCs 

 were captured in traps surrounded by apples com- 

 pared with 8 in traps in areas without apples (a 

 significant difference). These data suggest that 

 presence of food-type stimuli in association with 

 traps could be an important contributing factor to 

 enhancing captures of PC adults. 



Conclusions 



Our findings parallel the findings of Schmitt and 

 Berkett (1995) on the current and potential value 

 of using unbaited Tedders traps for monitoring PC 

 adults in apple orchards: chances are high that PC 

 injury to fruit will occur before adults are captured 

 in the traps. Chances of capturing PCs undoubt- 

 edly could be improved by employing more than the 

 one trap per five trees used by Schmitt and Berkett 

 or the one trap per five-ten trees used here. Even 

 one unbaited trap per tree may not be sufficient for 

 accurate monitoring information, however 



Our studies of the nature of PC responses to 

 unbaited Tedders traps suggest that only a small 

 proportion of PCs within 2-6 yards of a trap even- 

 tually arrives at the trap. (A cautionary note here 

 is that the data from which this conclusion is drawn 

 are from PCs that we had released; possibly they 

 were displaying escape behavior rather than tree 

 finding behavior). It appears that when such traps 

 are placed in open space (as would be the case when 

 between tree canopies), most PCs in flight bypass 



Fruit Notes, Winter, 1996 



