Studies on Eggs of Apple Plant Lice 



37 



first show green and until the small leaves project like 

 small squirrel ears (plate 2, fig. C). When the young leaves have 

 separated somewhat and appear as distinct structures, then the 

 dormant strength of spray will bum them (plate 2, fig. D). The 

 outline drawings of the twigs show the various stages of develop- 

 ment of a fruit spur or terminal bud. Stage A is a dormant twig 

 showing eggs of A. pomi scattered over its surface, stage B shows 

 a slightly swollen terminal bud with eggs of A. avencE about the 

 dormant buds and nymphs of A. avence near the green exposed tip. 

 Stage C is a more advanced stage of a swollen terminal bud and 



Plate 2. Fruit buds in different stages of 

 development. 



is in the last stage when it is safe to apply a dormant lime-sulfur 

 spray. Nymphs and eggs of A. avence are sho\Mi on this twig. 

 Stage D shows distinct and well separated leaves. The nymphs of 

 aphides, if present on such a twig, would be found to a consider- 

 able extent in between the leaves in protected places where it is 

 next to impossible to hit all of them with a contact insecticide. ^lost 

 varieties of apples with twigs in an advanced state cannot be 

 sprayed with a dormant strength of lime-sulfur without injuring 

 the young leaves. The length of the period from the time when 

 the buds first show green and until they are too far advanced for 

 dormant spray varies with the growing season. It may be less 



