Evaluation of Odor Lures for Use with 

 Red Sticlty Spheres to Trap 

 Apple Maggot Flies 



Alan H. Reynolds and Ronald J. Prokopy 



Department of Entomology, University of Massachusetts 



Red sticky spheres have shown promise as 

 an alternative to insecticide for control of apple 

 maggot flies in orchards. Such spheres 

 resemble ripe apples in size, shape, and color 

 and are visually attractive to maggot flies at 

 distances of up to about one yard. To increase 

 the effectiveness of these spheres, odor lures 

 also can be used, which serve to draw flies from 

 greater distances. In a study in 1995, we tested 

 two odor lures known to be attractive to apple 

 maggot flies in combination with red sphere 

 traps in commercial orchards. The odors were 

 butyl hexanoate (an odor emitted by ripening 

 apples) and ammonium carbonate (an odor 

 emitted from fly food sources such as bird 

 droppings). Butyl hexanoate is thought to be 

 more attractive to older, reproductively mature 

 flies (with a large egg load) seeking fruit in 

 which to lay eggs. Ammonium carbonate may 

 be more attractive to younger flies (with a small 

 or no egg load) seeking protein sources 

 necessary to achieve sexual maturity. We 

 hoped to discover which odor (or odors) would 

 optimally increase fly captures on spheres. 



Materials & Methods 



Each butyl hexanoate lure consisted of a 

 capped 15-ml polyethylene vial filled with 

 liquid hexanoate, which diffused through the 

 walls of the vial. Butyl hexanoate currently is 

 available from commercial sources as formu- 

 lated product in ready-to-use dispensers. Each 

 ammonium carbonate lure was a commercial 

 type (produced by Heath, Gainesville, FL), 

 consisting of a sealed plastic container with 1.7 

 grams of ammonium carbonate dispensed from 

 a small hole (a plastic flap covered the hole to 



protect against rainfall). Although these 

 ammonium carbonate lures are not available 

 for widespread commercial use, they represent 

 prototype lures that could be obtained easily by 

 growers. 



For our tests, four growers in central and 

 western Massachusetts generously agreed to 

 allow us to use trees in their orchards. In each 

 orchard, we selected plots of about 50 trees 

 (based on similarities in tree size and spacing) 

 which were located at the corners of larger 

 orchard blocks. Red spheres and lures were 

 hung on the perimeter trees of each plot at a 

 spacing of about five 5 yards between traps 

 (about 14 traps per plot). Traps were hung 

 about 5 feet above ground (depending on tree 

 size) so that there was no fruit or foliage within 

 8 inches of a trap (but as much as possible 

 outside of 8 inches). 



We tested four combinations of odor lures: 

 (1) butyl hexanoate only, (2) ammonium 

 carbonate only, (3) both butyl hexanoate and 

 ammonium carbonate, and (4) no odor. Each 

 orchard plot was assigned one of these odor 

 treatments. Odor lures were placed within 8 

 inches of the spheres (usually on the same 

 branch). 



Traps were deployed initially during the 

 first week in July and were maintained through 

 mid September. Once every 2 weeks, the traps 

 were checked and cleaned of captured apple 

 maggot flies and other insects. Odor baits were 

 replaced if necessary. 



Results & Conclusions 



The data from this experiment are 

 presented in Table 1. Red spheres baited with 



Fruit Notes, Volume 61 (Number 4), Fall, 1996 



