6 BULLETIN 416, U. S. DEPARTMENT OF AGRICULTURE. 



ondary nymph, or deutonymph. The activities of the deutonymph 

 are very similar to those of the protonymph and the duration of the 

 stage is about equal to the time required by the latter. The third molt 

 gives issue to the female. The single nymphal stage of the male 

 exhibits the same biologic activities as do nymphs of the female. 

 The time required for this stage, however, is a trifle longer than that 

 consumed by the female primarj^ nymphal stage, yet slightly shorter 

 than the combined periods of the two nymphal stages. In summer 

 the female requires, usually, about 10 or 11 days for the completion 

 of a generation, while the male requires about 9 or 10 days. 



During the course of the year, in the latitude of Batesburg, S. C, 

 there are ordinarily 16 or 17 generations, whereas in cooler portions 

 of the United States, naturally, there are fewer broods. In the 

 South the red spider passes the winter chiefly in the adult stage, and 

 even propagates considerably at a temperature slightly above freezing. 

 Feeding continues intermittently on several species of plants which 

 bear leaves throughout the winter season. 



DESCRIPTION AND HABITS. 



THE EGG. 



Description. — ^The eggs (PI. II, fig. 1) are almost perfect spheres. 

 When first deposited they are about as clear as water, but as incuba- 

 tion progresses they become opaque, turning a dark straw color 

 just before hatching. A series of spots becomes apparent, and in the 

 later stages of incubation the carmine eyes of the embryo are visible 

 through the shell. The eggs are deposited singly on the underside of 

 the host leaf and directly on the surface unless copious webbing is 

 present, in which case eggs are frequently attached to the fibrils 

 sUghtly above the surface of the leaves. Although very minute in 

 size, the eggs are relatively large as compared with the size of the 

 female red spider. A series of measured eggs averaged 0.129 mm. in 

 diameter. 



Number laid.— The number of eggs deposited by a single female is 

 subject to considerable variation, depending, apparently, on tem- 

 perature, locality, and suitability of food, but observations show that 

 practically all of the eggs hatch. Perkins in 1896 states that in 

 Vermont the brood varies between 50 and 100 eggs, that oviposition 

 covers on an average about 7 days, and that the average daily deposi- 

 tion is about 10 eggs. Worsham (1910) records 80 eggs as the average 

 fuU brood in Georgia, with the daily deposition varying from 1 to 12 

 per day, and covering an oviposition period of from 6 to 10 days. 

 He states that 94 eggs was the largest number recorded from a single 

 female. Ewing (1914), working in Oregon, found that females 

 averaged 41 eggs per brood, with 63 as the greatest number. His 

 records show 9 eggs as the maximum deposition per day, with 1 as a 



