8 BULLETIN 416, U. S. DEPARTMENT OF AGEICULTUEE. 



the leaf surface or among the fibrils of the webbing and rarely in- 

 volve an area greater in size than that of a dime. 



Table II. — Duration of the egg stage of the red spider. 



Brood. 



Average 

 date of 

 deposi- 

 tion. 



Averse 



date of 



hatching. 



Average 

 duration. 



Mean 

 tempera- 

 ture for 

 period. 



1 



2 



3 



4 



5 



6 



7 



8 



9 



10 



11 



12 



13 



Mar. 12 

 Mar. 24 

 Apr. 4 

 Apr. 27 

 May 19 

 June 10 

 July 16 

 Aug. 20 

 Sept. 2 

 Sept. 11 

 Sept. 14 

 Sept. 30 

 Oct. 31 



Mar. 27 

 Apr. 4 

 Apr. 13 

 May 3 

 May 23 

 June 13 

 July 19 

 Aug. 23 

 Sept. 5 

 Sept. 18 

 Sept. 19 

 Oct. 7 

 Nov. 16 



Days. 

 15.0 

 11.5 

 10.0 

 6.0 

 4.0 

 4.0 

 3.5 

 4.0 

 4.0 

 8.0 

 6.0 

 8.0 

 17.0 



°F. 



64 



58 



60 



67 



75.2 



81 



80.7 



79.8 



78.9 



69 



70.5 



68.3 



58.9 



THE LARVA. 



Description. — The newl}^ hatched larva (PL II, fig. 2) is round, 

 colorless, and 6-legged, and its body does not exceed that of the egg 



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Fig. 2. — Simultaneous curves of temperature and incubation of the red spider, showing the intimate rela- 

 tion between prevailing temperature and the time required for the development of the egg. (Original.) 



in size. The two portions of the body, cephalothorax and abdomen, 

 are rather distinctly marked at this time by a transverse suture. 

 The most conspicuous feature of the newly-hatched larva is its 

 bright carmme eyes. It begins feeding at once, and as feeding pro- 

 gresses the larval color deepens to a green or ferruginous green. A 

 characteristic feature of the larva is the shortness of the legs due to 

 inflation of the sHghtly hardened leg segments. Although the tarsus 

 and the femur are the longest joints of the larval legs, there is no 



