0.70 



0.00 



Unbailed Baited 



Pyramid 



Unbailed Baited 



Circle 



Unbailed Baited 



Cylinder 



Trap type 



Figure 1. Captures of plum curculios on unbailed and baited pyramid, cylender, or circle traps in commercial 

 orchards. Bars not superscribed by the same letter are significantly different at odds of 19 to 1. 



abundance of PCs in traps and amount of injury never 

 exceeded 0.37 for any type of unbailed or baited trap, 

 and the r value describing the relationship between time 

 of capture of PCs in traps and time of injury did not 

 exceed 0.24 for any type of unbailed or baited traps. 



In unsprayed orchards, significantly more (about 

 eight times more) PCs were captured by pyramid traps 

 than by cylinder traps, with clear Plexiglas traps posi- 

 tioned next to apple trees capturing slightly, but not 

 significantly, more PCs than cylinder traps (Figure 2). 

 Captures by unbailed versus baited traps did not differ 

 significantly among any of these three trap types (Fig- 

 ure 2). However, baited clear Plexiglas traps placed at 

 the edge of woods captured significantly more PCs 

 (about 14 times more) than similarly positioned 

 unbailed traps (Figure 2). In contrast to above find- 

 ings in commercial orchards, r values describing the 

 relationship between abundance of PCs in traps and 

 amount of injury ranged between 0.75-0.89 for unbailed 

 and baited pyramid and clear Plexiglas traps placed 

 next to perimeter apple trees. Less encouraging, how- 

 ever, were r values describing relationship between 

 time of capture of PCs in traps and time of injury, which 



did not exceed 0.22 for any type of unbailed or baited 

 trap. 



Conclusions 



Perhaps the most encouraging finding from this 

 study was the positive response of PCs to baited sticky 

 clear Plexiglas traps placed next to woods. In the fu- 

 ture, a simpler and more attractive version of this type 

 of baited trap could be very useful for monitoring the 

 beginning, peak and (most importantly) the end of im- 

 migration of overwintering PCs from woods or 

 hedgerows into orchards. 



The reason why odor bait significantly enhanced 

 PC captures by clear Plexiglas traps near woods but 

 not captures by any of the various types of traps placed 

 adjacent to, beneath or within canopies of perimeter 

 apple trees is uncertain but could be related to use of 

 too high a dose of ethyl isovalerate, one of the odors 

 used a component of the bait. The extra high dose 

 used here turned out to be about six times greater than 

 the medium dose found to be attractive in subsequent 

 tests (see following article) and, at close range for PCs 



Fruit Notes, Volume 64 (Number 3), Summer, 1999 



