- 10 - 



It is during bloom that female EAS deposit their small white 

 eggs in the developing fruit. The egg-laying scar appears as a tiny- 

 brownish spot near the top of the caylx cup. The larvae hatch in 

 about 10 days, with the first visible larval feeding damage being 

 a small dark brown trail tunneled near the surface of the fruit. 

 As a sawfly larva develops, it takes on the appearance of a dark- 

 headed white caterpillar which migrates from fruit to fruit, tun- 

 neling directly to the core and feeding. Later larval damage is 

 characterized by large masses of dark-colored frass at the feeding 

 tunnel entrances. Most EAS-damaged fruit is lost during June drop. 

 However, some remain on the tree and appear at harvest scarred 

 with long yellowish scabs originating at the caylx and winding 

 around the fruit surface. 



It takes about 3 weeks and 4 to 5 fruits for a sawfly larva 

 to mature. It then drops to the soil where it forms a cocoon, re- 

 maining in that state until adult emergence the following spring. 

 Thus, there is only one generation annually. 



Most commercial apple orchards do not have a population of 

 sawflies arising from within the orchard, the reason being that 

 standard pesticide spray programs include a petal fall spray which, 

 if applied at the appropriate time, kills most or all of the lar- 

 vae. However, since most New England orchards are surrounded by 

 areas dotted with wild or abandoned apple trees, there is a contin- 

 ued threat of invasion by sawfly adults migrating in from the out- 

 side. To improve the orchardist's ability to determine if EAS is 

 active in his orchard and, if so, to aid in the appropriate timing 

 of spray applications against sawfly, we initiated the following 

 research aimed at development of an effective and convenient trap 

 for monitoring EAS adult population levels. 



First, we spent many hours observing EAS adult activity in 

 abandoned apple trees. Females were watched as they flew about 

 blossoming trees on warm sunny days in May. We observed them 

 feeding on pollen in open or partially opened blossoms and laying 

 eggs in the caylx cup. Most adults were seen to land near or di- 

 rectly on the blossoms. This information led us to study (with 

 the aid of a spectrophotometer) the visual reflectance pattern of 

 apple blossom parts and to field test white surfaces that might 

 prove to be effective blossom mimics. 



In our first experiment, conducted in an abandoned orchard, 

 we compared 6x8 inch rectangles hung vertically from apple tree 

 branches and coated with the following colors of enamel paint: 

 white, gray, black, yellow, green, blue, orange, or red. Clear 

 plexiglas and aluminum-foil-covered rectangles were also tested. 

 All traps were coated with a thin layer of Bird Tanglefoot*, a 

 clear sticky substance that captures alighting insects. The 

 results (Table 1) show that more EAS were captured on the white 

 rectangles than any others tested. The fact that white captured 



*Trade name 



