288 



which happen to be at that time less than three days okl, while on the 

 day after the spraying new larvte will be born to take the place of 

 those jnst killed. 



Observations upon isolated individuals show that the newly-hatched 

 larvje, after crawling about for a few hours, settle down and commence 

 at once to form a scale. The secretion is white and fibrous. In two 

 days the insect becomes invisible, being covered by a pale, grayish- 

 yellow shield, with a projecting nipple at the center. This nipple is at 

 first white in color. Twelve days after hatching the first skin is cast. 

 The males at this time are rather larger than the females, and have 

 large purple eyes, while the females have lost their eyes entirely. The 

 legs and antennjie have disappeared in both cases. Six days later the 

 males begin to change to pupa, while the females have not yet cast the 

 second skin. At this time the females are so tightly cemented to the 

 scale that they can not be removed without crushing. In two or three 

 days more, or twenty to twenty-one days after hatching, the females 

 cast their second skin, which splits around the margin of the body. 

 At 24 days the males begin to issue, emerging from their scales, as a 

 general thing, at night. At 30 days the females are about full grown, 

 and embryonic young can be seen within their bodies; and at from 33 

 to 40 days the larvte begin to make their appearance. 



These observations were made upon young which were born of over- 

 wintered mothers late in June, but it must be remembered that similar 

 larvsB had been hatching since the middle of May. The period of 38 

 to 40 days may be accepted as the length of time occupied by a single 

 generation; but, while this particular generation came out in the 

 insectary about the first of August, the adults of the second generation 

 from the earliest-born individuals would have made their appearance 

 toward the end of June. Full-grown females which began to give 

 birth to the second generation of young on August 1 were kept in 

 view. Three weeks later they were seen still to contain numerous 

 embryos. Young larvai were running about, while others of the same 

 generation were in all stages of development. The male scales were 

 fully formed, and some contained mature pupa'. The small trees upon 

 which these insects were colonized the third week in June were almost 

 completely covered with the scale. The larviie evidently made no effort 

 to crawl aAvay from the tree, and none, in fact, reached the rim of the 

 flower-pot. The greatest distance away from the tree at which larvae 

 were noticed was about two inches. Up to this time the insects had 

 confined themselves almost entirely to the branches, and the leaves 

 were still quite free. The first males of the second generation were 

 noticed on August 27. By September 7, or five weeks and a half after 

 the adult females of the first brood began to give birth to young, some 

 of them were still living and giving birth to occasional young. The 

 majority of them, however, were dead, or nearly exhausted, while their 

 first larvje were almost ready to reproduce. Five days later a few of 



