502 Appendix. 



Life-History. 

 This insect in America passes the winter in either an immature or 

 nearly mature state, protected by its scale. In the late spring the female 

 reaches maturity and the male comes forth as a two-winged insect. The 

 winged male is orange in colour, with a dusky-brown prothorax, brown 

 transverse band on the thoracic shield, and purple eyes ; the wings are 

 dusky, iridescent with yellow and green ; it has a long anal style, dusky 

 bi"own in colour. The females, having been fertilised by the winged male, 

 commence to produce young. Eggs are not laid by this species as a rule, 

 but young are produced direct. The female continues to give birth to 

 young for six weeks and then dies. It is generally believed that this 

 insect is always viviparous, but Riley, Matthew Cook and Klee state that 

 white or yellow ovate eggs are also laid. The young or larvge are minute 

 active six-legged creatures, orange in colour, and about xo%o ^"^^ 

 long. When they crawl forth from under the female scale they wander 

 about upon the trees for some little time, and then fixing their long 

 proboscides into the plant remain sedentary and soon commence to form a 

 waxy covering or scale. At first this scale is white and fibrous (Howard). 

 In two days the larva is said to become invisible, being covered with a 

 pale greyish-yellow shield, with a projecting white nipple in the centre. 

 In this stage both male and female scales are alike, but about twelve 

 days later the larva undergoes the first moult, when the scales of the two 

 sexes become distinct. Both immature male and female beneath the 

 scale will be seen to have lost their legs and antennae, the females their 

 eyes, but the males have large purple eyes. About eighteen days after 

 birth the male enters the propupal stage, in which a new set of legs, etc., 

 become formed, and six days later the winged male hatches out. The 

 females keep sedentary and reach maturity about thirty days after birth 

 and give rise to young about a week later. At least five generations 

 occur in the year in America, if not more. 



Rate of Increase. 

 This jjest increases with extraordinary rapidity in America. Experi- 

 ments conducted by the Department of Entomology at Washington have 

 proved beyond doubt that a mature female produces nine to ten young 

 every twenty -four hours for six weeks, making a total of 400 individuals 

 from one insect. From accurate observations in connection with these 

 experiments it was estimated that one winter female will give rise to a pro- 

 geny of 3,216,080,400 in one year under the most favourable conditions. 



Natural and Artificial Distribution. 

 The San Jose, like other scales, can be distributed in a number of 

 ways from tree to tree, orchard to orchard, and country to country. 



