THE RED SPIDER ON THE AVOCADO. 5 



THE, EGG. 



The egg (fig. S, a,b) is globose in shape, smoky amber in color, and 

 bears a stalk at its apex. Guy fibrils are occasionally seen connecting 

 the egg with the leaf. 



The eggs are deposited singly and when the leaf first becomes in- 

 fested are generally found located along the midrib at the base of the 

 leaf. As the activities of the mites increase with succeeding genera- 

 tions, the eggs may be found scattered over the entire leaf. 



The incubation period varies according to the temperature and gen- 

 eral climatic conditions. (See Table 1.) During midwinter, with 

 mean daily temperatures between 60° and 70° F., incubation requires 

 from 7 to 11 days. During April and May the incubation period 

 averaged from 4 to 5 days with mean temperatures between 70° and 

 80° F., in rearing experiments with this species. In hatching, the 

 shell of the egg splits more or less completely around and the larva 

 easily extricates itself. During the height of the red spider season 

 leaves will be observed heavily covered with hatched eggshells which 

 adhere to the leaf and impart to it a whitish cast. 



Table 3. — Length of the egg stadiion. 



No. 



Date de- 

 posited. 



Date 

 hatched. 



Dura- 

 tion. 



Mean 

 temper- 

 ature. 



No. 



Date de- 

 posited. 



Date 

 hatched. 



Dura- 

 tion. 



Mean 

 temper- 

 ature. 



1 

 2 

 3 

 4 

 5 

 6 



Oct. 15 

 Oct. 22 

 Nov. 8 

 Nov. 30 

 Dec. 18 

 Jan. 1 



Oct. 20 

 Oct. 26 

 Nov. 13 

 Dec. 8 

 Dec. 25 

 Jan. 11 



Days. 

 "5 



4 

 5 

 8 

 7 

 10 



o p 



78 

 77 

 72 

 70 

 65 

 58 



7 

 8 

 9 

 10 

 11 

 12 



Jan. 21 

 Feb. 15 

 Mar. 15 

 Apr. 1 

 May 31 

 July 11 



Feb. 1 

 Feb. 22 

 Mar. 20 

 Apr. 5 

 J line 5 

 July 15 



Days. 

 11 

 7 

 5 

 4 

 5 

 4 



o p 



60 

 70 

 72 

 75 

 76 

 79 



THE LARVA. 



The newly hatched larva (fig. 3, c) is round, very light yellow. 

 possesses six legs, and in size does not exceed that of the egg from 

 which it emerged. It is very delicate, and a marked characteristic 

 is its possession of conspicuous carmine eyes. During the process of 

 development and feeding the young creatures commence to change 

 color. The larva measures 0.17 mm. in length on an average. 



As with practically all mites the larva stage is divided into an 

 active and a quiescent period. The former is passed while the larva 

 is feeding and the latter in preparation for the first molt. The 

 time spent in the quiescent period of the larva stage averages in most 

 instances only a few hours. The average length of the larval period 

 is 2.58 days. • 



