150 Amials Entomological Society of America [Vol. X, 



circular. In the case of the latter the presence of a pit seems 

 to be indicated by a small swelling on the bark. Alongside 

 the insects are found fragments of the wax covering and of the 

 exuviae of previous instars. 



The life histories seem to be identical with that of Xylococcus 

 betidcB Perg. as previously described. I have not succeeded, 

 however, in finding a stage in the development of the male 

 insect of macrocarpce, or quercus, or alni, corresponding to 

 Pergande's second stage of betiilce. The mouth-parts are very 

 long, and when the larvae first hatch can be seen coiled inside 

 the insect (PI. XIII, Fig. 4). The young insects have well 

 developed legs and move about actively before settling down. 

 The male and the female are apparently not distinguishable in the 

 first stage. After the first moult the female loses its legs and 

 antennae and for three successive stages is apodous. Size, 

 difference in number of the wax pores, and structural differences 

 in the stigmatal tubes and anal tube serve to distinguish these 

 stages. After the fourth moult the adult female issues. The 

 insect has now regained the legs and antennae, but lost the mouth 

 parts (PI. XIII, Fig. 5). The insect may, without escaping 

 from the exuvia of the fourth stage, rupture the end of the 

 exuvia and present the posterior end of the body at the crevice 

 in the bark for impregnation by the male, or she may escape 

 from the pit and move about freely over the tree. In this case 

 she finally settles under some projection of the bark and spins 

 a cushion of flocculent wax beneath and a covering of powdery 

 wax above her (PI. XII, Fig. 4). When the eggs are laid the 

 abdomen becomes concave on the lower surface with the lateral 

 margins revolute, so forming a pocket in which the eggs lie 

 buried in wax until they hatch (PI. XIII, Fig. 6). After 

 egg-laying the female dies, the anterior part of the body 

 shrivelling up. 



At the second moult the male insect becomes apodous, 

 closely resembling the female of the third stage. In the fourth 

 stage the legs and antennas reappear and the mouth-parts and 

 the chitinized anal tube are lost. The insect now emerges and 

 wanders freely over the bark, finally settling under some raised 

 part of the bark. It immediately begins to spin a long slender 

 cylindrical cocoon of flocculent wax and within this the trans- 

 formation to the pupal stage takes place. The pupae have well 



