364 



REPORT OF STATE BOARD OF HORTICULTURE. 



The adult female g-ives birth immediately to living" young, differing in 

 this respect from most other scale insects. Ordinarily eggs are deposited 

 beneath the scale, which in the course of a longer or shorter time hatch, and 

 the young larvae make their escape and migrate to different parts of the 

 plant. In the case of some scale insects the female fills its scale with eggs 

 in the fall and perishes, the eggs wintering over and hatching the following 

 spring-. In others the insect hibernates in the nearly mature condition, as 

 does the San Jose scale, and deposits eggs in the spring or early summer. 

 The viviparous habit, or the giving birth to the living young, possessed by 

 the San -Jose scale, finds a parallel in many other insects and frequently in 

 plant-lice. In the case of the San Jose scale the eggs are fairly well formed, 



Fig. 3— Young larva and developing scale : a, Ventral view of larva, showing 

 sucking beak with setse separated, with enlarged tarsal claw at right ; b, dor- 

 sal view of same, somewhat contracted, with the first waxy filaments ap- 

 pearing; c, dorsal and lateral views of same, still more contracted, illus- 

 trating further development of wax secretion ; d, later stage of same, dorsal 

 and lateral views, showing matting of wax secretions and first form of 

 young scale— all greatly enlarged. (Original.) 



a few at a time, within the body of the mother. What takes the place of 

 the eggshell consists of a verj' delicate and thin membrane — the amnion — 

 which incloses the developing larvse and which at the moment of birth is 

 cast off, and remains attached to or partly within the oviduct. The amnion 

 is probably pushed out by the next larva in turn. The difference between 

 this mode of birth and the ordinary method through the medium of true 

 eggs is simply that what corresponds with the egg is retained by the female 

 until the larva is developed, instead of development of the larva progressing 

 after the egg leaves the parent. 



