Studies on Eggs of Apple Plant Lice 9 



from this laboratory method were very satisfactory during both 

 seasons for they exactly duplicated the results obtained in the or- 

 chard where lime-sulphur, lime-sulphur combined with nicotine, and 

 "Scalecide" were used. The loss of eggs In handling the twigs 

 usually did not exceed 10 per cent, and in most cases it was less than 

 10 per cent. When a few eggs were lost, it is assumed that the loss 

 was proportionally shared by eggs which wou!:l hatch under normal 

 conditions and those that would not hatch. 



Morphology and Behavior of the Egg 

 The eggs of A. avemc, A. pomi and A. sorU are glossy black, 

 (u-al in f(u-m and slightly flattened on their ventral aspects, adjacent 

 to the twig (plate 1, fig. 1 and G). The eggs vary somewhat in size, 

 but generally speaking they are about 1/45 inch in length and 1/90 

 inch in width. According to Baker and Turner (2) the eggs of A. 

 pomi average 0.572 mm. by 0.281 mm., and of A. sorhi 0.550 nun. by 

 0.272 mm. The newly laid eggs are soft and retain this consist- 

 ency, more or less, even after the outer shell hardens. A new^ egg 

 has' a light yellow color which soon changes to a green tinge and 

 then gradually darkens to a deep black. This change usually takes 

 place in a few days, one to four according to Baker and Turner. 

 During the past season it was noted that a small percentage of the 

 eggs of A. avence required ten or more days to change to a glossy 

 black and some never changed, but retained their greenish tinge 

 throughout the winter. Apparently these eggs are abnormal, for 

 they did not hatch, so far as observed. Other abnormal eggs had a 

 light brown tinge and they did not hatch. 



The glossy appearance, particularly true of a newly deposited 

 c-^^, is due to the moist glutinous layer which entirely surrounds it. 

 This layer t hardens and glues the egg to the twig and also acts as 

 a protective layer to conserve the moisture content of the developing 

 embryo. After the outer layer hardens one can remove it by care- 

 ful dissection, and then its thin, colorless, &emi-transparent and 

 somewhat tough consistency can be seen. This layer probably 

 originates as a secretion from accessory glands in the oviparous 

 female, at least such glands are present in the female. 



The black or pigmented portion p of the egg is entirely confined 

 to the slightly tough and elastic membrane directly beneath the outer 

 semi-transparent layer. The glossy black and moist appearance 

 of this layer is readily observed in eggs where the outer semi-trans- 

 parent layer t has split (plate 1, fig. 2-10). The pigmented layer 

 undoubtedly is a true chorion for it is found about the egg as a dis- 

 tinct pigmented layer when the egg has nearly completed its forma- 

 tion within the oviparous female. The chorion is secreted by the 

 ovarian cells about the ovum. The pigmented layer may serve as a 

 protective covering, but. so far as water conservation is concerned 



