THE BED SPIDER ON COTTON. 



upon the leaf. The eggs are usually clustered rather closely and 

 rarely occupy an area greater in size than that of a dime. Feeding 

 continues interruptedly throughout the period of egg laying and the 

 affected area of the leaf becomes thickly dotted with the blackish- 

 green puncture marks. Meanwhile a wine-red spot has appeared on 

 the upper surface of the leaf directh^ over the young colony, which 

 spreads as the colony increases and may finally color the entire leaf. 

 As the eggs hatch the larvae remain close to the place of their birth. 

 The mites seem of a decidedly social disposition. In a young colony 

 there is usually little web formed, but where the spiders are very 

 abundant the web may become quite conspicuous. It doubtless 

 affords some protection from adverse weather conditions, and upon 

 several occasions hostile insects have been observed ensnared and dead 

 among the fibers. New females, aft«r mating, either select an attrac- 

 tive spot on the leaf, or migrate upward 

 to a more tempting leaf, or in som*^ 

 cases may even travel to another plant. 



THE VIOLET AS HOST. 



When cotton dias or becomes untempt- 

 ing in the late fall an exodus of red 

 spiders from the cotton fields occurs in 

 the effort to find more suitable food 

 plants. At this time cotton mites maj^ 

 be easil}'^ foimd on a number of native 

 and cultivated plants, prominent among 

 Avhich are cowpeas, tomato, Jamestown 

 Aveed, ironweed, and cultivated violets. 

 INIost of these plants die after the frosts, 

 but the violet remains somewhat green 

 throughout the winter, and it is upon 

 this plant, probably, that the vast majority of mites overwinter. Out 

 of many cases of cotton infestation investigated the vast majority 

 have indicated most clearly that the original source of the pest was 

 doubtless this innocent pet of the housewife, the English violet. 

 (See fig. 2.) 



OTHER HOSTS. 



Fig. 2. — Diagram showing liow vio- 

 lets growing in dooryard give 

 rise to red spider infestation in 

 adjoining field. The infestation 

 is most severe near the yard. 

 This diagram is typical of many 

 eases found during 1911. (Orig- 

 inal.) 



In all, the red spider has been found in 1911 upon over 50 species 

 of plants, including weeds, ornamental plants, and garden and field 

 crops. Upon most of these the pest was only occasionally seen, but 

 it was found commonly throughout the active season upon the fol- 

 lowing plants: Beans, cowpeas, dahlia, ironweed, Jerusalem-oak 

 weed, Jamestown weed, okra, tomato, wild blackberry, and Avild 

 ceranium. 



