8 - 



All foliage and fruit within 12 inches of all sides and top and 

 bottom of a sphere should be removed. But beyond this distance, 

 there should be as much fruit and foliage as possible to attract 

 flies into the general area. The sphere should be hung at head- 

 height or higher. 



This past summer, Everett Wilder and Dom Marini (regional 

 fruit specialists in Massachusetts) and I hung 1-4 of these un- 

 baited sticky-coated red spheres plus 1-4 baited sticky-coated day- 

 light fluorescent yellow rectangles in each of 9 commercial apple 

 orchards in Massachusetts to monitor the activities of apple mag- 

 got flies. We found that early in the fly season (up to July 10), 

 when the flies had a high drive to feed, the rectangles generally 

 attracted slightly more maggot flies than the spheres. But after 

 that time, as the flies matured and developed a higher drive to 

 mate and lay eggs, the spheres became 2-15 times more attractive 

 than the rectangles. This was true even though the rectangles 

 were usually freshly renewed every 3 weeks, while the spheres re- 

 mained unaltered. 



We captured mature apple maggot females on the spheres in 8 

 of the 9 commercial orchards, in some cases as many as 5 females/ 

 week/sphere. Because the flies are unable to perceive the spheres 

 at a distance greater than about 1 yard, these captures suggested 

 that other uncaptured maggot flies were probably present in the 

 immediate vicinity, constituting an egglaying threat to the apples. 

 Protective maggot sprays were therefore advisable. Sphere capture 

 data proved especially helpful toward the end of the season, when 

 there was uncertainty as to when to stop spraying for maggot. In 

 at least 2 orchards, considerable numbers of mature females were 

 captured after mid-August, and as a result, an additional protec- 

 tive spray was applied to Cortlands and Delicious. 



Maggot can be a serious pest, the average female capable of 

 laying 300 eggs, and therefore stinging and infesting 300 fruits. 

 All growers, especially those having early-season varieties, should 

 be aware of the potential destructiveness of this insect. In fact, 

 this year in 2 of the best commercial orchards in Massachusetts, 

 we found substantial numbers of fallen Wealthies and Puritans in- 

 fested by fully developed maggot larvae. In these and other orch- 

 ards, we also observed maggot egg-laying stings and early larval 

 development in some Cortlands and Delicious. 



Just as the unbaited red spheres are effective in monitoring 

 apple maggot populations, they also are of real usefulness in di- 

 rectly controlling the flies in small orchards of about 100 trees 

 or less. For example, in my own insecticide-free, 150-tree orch- 

 ard in Wisconsin in 1974, I hung 6 of these spheres in each fruit- 

 ing tree and captured more than 9500 apple maggot flies. If un- 

 controlled, this number of flies would have given rise to about 

 30 eggs/apple in my orchard. But I received an average of fewer 



