17 



mo^st'cfr/T ''f '"''^' "" °* °"'" "^^^^^■'i trees, but appears to be 



winter birir P'" '°^ P'"'='- '^^'^ ^--* i« represented in 

 wmtei by partly grown specimens whose development was stopped by 

 the cold weather. They resume, growth in the early spring; the 

 males soon appear, mate with the females, and the latter give birth to 

 Imng young. At Washington, D. C, this time is about the middle 

 ot May, and the young continue to appear for about six weeks. The 

 larva crawls off a little way, settles, and within two davs begins the 



Fig, 6, — Aspidiotus perniciosus: a, female; b, margin of pygidium magnified. (Howard and Marlatt.) 



secretion of its scale. This young scale is at first white with a swell- 

 ing in the center. If it is situated on green tissue it is apt to pro- 

 duce a redness. In a few days the pale scale becomes nearly black, 

 with a central nipple surrounded by one or two depressed rings. This 

 form is very characteristic of the species. In about twenty-five days 

 another brood of males appears, and in thirty daj'S the females become 

 adult. At about thirty -five or forty days of age the females begin to 

 give birth to living young. Since one of these mother scales may 

 have been born six weeks before another, it results that there is a 



24842— No. 34—02 2 



