287 



as the affected locality is near the headquarters of an active fruit- 

 growers' association, remedial work is in proper train. Dividing the 

 expense between the station and fruit-growers, California washes have 

 been applied with care and thoroughness, and at last reports a deter- 

 mination existed to repeat the application as often as might be neces- 

 sary before spring. 



LIFE-HISTORY OF THE INSECT. 



Although this insect has been known in California for about twenty 

 years, its life-history has not been carefully worked out by California 

 writers. Professor Corastock described simply the male and female 

 scales, and the body of the adult female. The male was unknown to 

 him. In his work on the Injurious Insects of the Orchard, Vineyard, 

 etc., published at Sacramento in 1883, Mr. Matthew Cooke briefly 

 described the male insect and published a crude figure of it. He fur- 

 ther stated that the species produces three broods in California, the 

 first "about the time the cherries begin to color, the second in July, 

 and the third in October." The statement is made by Comstock that 

 the eggs are white, and Cooke further says that "each feiiuile produces 

 from 35 to 50 eggs," 



Upon the appearance of the insect in the East, potted pear trees 

 were secured for the Insectary of this Division, and colonies of the 

 scale were established on them. Their life-history has been followed 

 with more or less care throughout the season, and the following brief 

 statement of the life-cycle of the insect is based upon daily observa- 

 tions made during the summer by Mr. Pergande. 



It had already been ascertained during the late summer and fall of 

 1893 that the insect is viviparous, that is, gives birth to living young, 

 and that it does not lay eggs. We were unable to reconcile this con- 

 dition of affairs with the statements just quoted from Comstock and 

 Cooke, but it occurred to us that, as with certain of the plant-lice, 

 there might be Avinter eggs, with viviparous females in summer. When 

 winter came on, however, it was found that the insect hibernated in 

 the nearly full-grown feimile condition, and that these females, about 

 the middle of May, began to give birth to living j'oung as their ances- 

 tors did the previous fall. In no instance, therefore, have we observed 

 the egg (unless the young still in the body of the female and enveloped 

 in tlie embryonic membrane may be so called). Over- wintered females 

 continued to give birth to living young day after day for six weeks. 

 This condition of affairs produces, early in the season, a confusion of 

 generations, which makes observations upon the life-history of the 

 insect extreinel}' difficult, and only to be accomplished by isolation of 

 individuals. It also seriously complicates the matter of remedies, 

 since, as numbers of the larva^ are hatching every day, and as they 

 begin to form their almost impervious scales in two or three days, a 

 spraying operation at any given time will destroy only those larvai 



