THE RED SPIDER ON THE AVOCADO. 

 Table 4. — Length of the second nijmplial stadium. 



No. 



1 



2 

 3 

 4 



5 

 6 



Date 

 emerged. 



Date 

 molted. 



Dura- 

 tion. 



Mean 

 temper- 

 ature. 



No. 



Date 

 emerged. 



Date 

 molted. 



Diira- 

 tion. 



Mean 

 temper- 

 ature. 



Oct. 22 

 Nov. 3 

 Nov. 23 

 Dec. 18 

 Jan. 1 

 Jan. IS 



Oct. 25 

 Nov. 6 

 Nov. 25 

 Dec. 21 

 Jan. 4 

 Jan. 24 



Days. 

 3 

 3 

 2 

 3 

 3 

 3 



"F. 

 76 

 77 

 75 

 70 

 68 

 63 



7 

 S 

 9 



10 

 11 

 12 



Feb. 6 

 Feb. 26 

 Mar. 25 

 Apr. 9 

 June 8 

 July 16 



Feb. 10 

 Feb. 29 

 Mar. 28 

 Apr. 12 

 June 10 

 July 18 



Dai/s. 

 4 

 3 

 3 

 3 

 2 

 2 



°F. 

 65 

 70 



72 

 75 

 76 

 79 



BIOLOGICAL DATA. 



Wehhmg. — Unlike the majority of red spiders this species does not 

 spin an extensive web and carries on its depredations on the foliage 

 practically unprotected. The only indications of any webbing made 

 by this species are the mere fibrils attached to the apex of the eggs 

 when deposited (fig. 3, a). 



Average length of life period. — The length of the life period of the 

 adult mites varies greath' with the season and temperature and possi- 

 bly other conditions. Experiments on the life history of this species 

 showed that adults emerging November 25 came to their natural 

 death during the period January 1 to 15, wdiile those emerging June 

 10 succumbed between July 1 and 15. This shows that during the 

 dry winter months approximately two months are required from the 

 time of emergence to the completion of the life period, while during 

 the humid summer months approximately a month is required. 



MolfJng fpoces^. — Before molting the mite securely attaches itself 

 to the leaf. In emerging from the quiescent stage the old skin splits 

 transversely along the cephalothoracic-abclominal suture. Following 

 the splitting of the skin the anterior end of the mite is slowly drawn 

 from the old skin. With the use of its fore legs the mite forces its 

 waj^ out from the shell. 



Parthenogenesis. — Some immature individuals were isolated on a 

 number of plants. From these individuals virgin females were ob- 

 tained. These females produced eggs and in each instance the re- 

 sultant individuals were males. 



Migration. — There does not seem to be an alternate host of this spe- 

 cies. Individual red spiders may be found on the avocado at any time 

 during the year in varj^ing numbers, and never leave the tree for want 

 of a new or alternate host plant on which to feed. In a grove the red 

 spiders are spread from tree to tree by the wind, birds, etc. 



Generations of the species. — The generations of the avocado red 

 spider fluctuate as to number and overlap considerably. In years of 

 little rain during the fall the red spiders come in evidence more 

 quickly than wdien rains occur earlier. Intermittent rains frequently 



