8 FARMERS BULLETIN 831. ' 



During the spring and summer months the red spider, in the 

 latitude of vSouth Carolina, requires on an average a little less than : 

 11 days for the completion of a generation. In an average season ' 

 at Batesburg, S. C, there are 17 generations of red spiders. 



In developing from the egg to the adult stage the red spider 

 foUows one or the other of two courses, depending on the sex. With 

 the female, the egg hatches in about four days to a tiny, colorless, 

 6-legged form known as a larva, which feeds eagerly and in about 

 two days in summer time sheds its skin and becomes an 8-legged 

 form called the primary nymph. The latter feeds in a manner very 

 similar to that of the larva and becomes greenish or yellowish in 

 color with conspicuous blotches at the sides. At Batesburg this 

 stage requires a trifle over two days for completion, when the skin ' 

 again is shed and the secondary nymph appeai-s. The latter lives I 

 about as the preceding stages do and becomes more nearly the size 

 and color of the adult. After about one and nine-tenths days 

 another molt or skin shedding occurs, which gives origin to the k 

 adult female. Thus, in the most favorable season, the females f 

 require about nine days to mature. 



The development of the male is very similar to that of the female, 

 with the difference that the secondary nymphal stage is lacking. 

 The other stages, however, are shghtly lengthened, so that the male 

 red spiders usually complete their development only one day sooner 

 than the females. 



In establishing herself upon cotton the female selects a concave 

 area between the under veins of the leaf and after a brief feeding 

 period of about 18 hours begins to deposit her eggs. Usually the 

 eggs are clustered rather closely, rarely occupying an area greater 

 in size than that of a dime. 



For about 8 to 10 days the female lays usually about six eggs 

 a day, making a total of about 50 to 60 eggs. Feeding contiimes 

 from time to time throughout the egg-laying period. The average 

 duration of adult life in summer, m South Carolina, is about 12 

 days. This period mcreases as the weather becomes cooler, and in 

 winter the i.dults often live for 150 days. 



RELATION OF WEATHER TO BREEDING. 



Clmiatic conditions influence the development of the red spider 

 to a marked extent. The influence may be either harmful or bene- 

 ficial. In the course of the year the occurrence of the pest under- 

 goes many changes. During December, January, and February the 

 red spider merely maintains itself, but during March conditions 

 usually become a little more favorable. Through April and May 

 development progresses most rapidh', and infestation reaches its 

 height on miscellaneous plants by Jmie 1. Beginnuig about the end 



