by September. Fortunately, there is considerable natural mortality, 

 even in the absence o£ pesticide-resistant parasites or predators, 

 so that the full biotic potential o£ this pest is rarely if ever rea- 

 lized. 



In this article, we will outline the biology and monitoring 

 methods of STLM, and suggest various possible approaches to control. 

 Drs. Weires, Leeper and Reissig have been studying these aspects in 

 New York since 1976. Much of what we will describe here is drawn 

 from their excellent work, some of which is published in the 1977 

 Proceedings of the New York State Horticultural Society , the August 

 1977 issue of the Journal of Economic Entomology , the March, 1978 

 issue of the American Fruit Grower^ and New York Food and Life 

 Sciences Bulletin 85 (1980")"^ 



BIOLOGY 



Description of Stages and Life History . STLM overwinter as pupae 

 in apple leaves on the orchard floor. First generation adults begin 

 to emerge when Mcintosh trees are in the green tip stage of develop- 

 ment. The adults are small (about 1/8 inch long) light brown moths 

 with white wing spots that appear as transverse bands when the wings 

 are folded. Though frequently found resting in ground cover vege- 

 tation during the day, they are particularly active from late after- 

 noon through dusk, and may be found then on the undersides of leaves, 

 the tree trunk, or interior scaffold limbs. The tiny white eggs 

 (1/75 inch diameter) are laid singly on the undersurface of the leaves 

 and require about 6-10 days to hatch. First generation eggs are 

 laid predominantly on fruit-cluster leaves in the lower half of the 

 interior of the tree. Second and third generation eggs may be laid 

 on any leaves anywhere in the tree. In addition to apple leaves, 

 leaves of other trees such as crabapple, hawthorne, quince, plum, and 

 wild cherry may also serve as STLM hosts. 



The larva develops in the same leaf on which the egg was laid. 

 Larvae develop first through 3 sap-feeding stages and then 2 tissue 



an irregular oval, circumscribing the area within which the larva 

 will eventually develop to maturity. By the 3rd larval stage, the 

 lower leaf surface tissue circumscribed by the trail will have a light 

 green or whitish appearance and can be readily removed, revealing 

 the feeding larva. Tissue feeding larvae feed just below the upper 

 surface, producing tent-like mines with whitish spots visible when 

 the green tissue has been eaten. The last-stage larva transforms into 

 a pupa in the leaf tissue, with the pupal stage lasting about 10 days. 

 The entire life cycle requires about 35-55 days, depending on weather 

 conditions . 



