CHAPTER 28 



plant pests 



Arachnides 

 Red Spider. Tetranchyus bimaculatus Harw. 



Red spiders or spinning mites (fig. 76, b) are 

 very troublesome to greenhouse crops ; cucumbers are 

 especially attacked by them. Eggplants and toma- 

 toes are next in preference. Of the flowering plants, 

 roses, violets, sweet peas, carnations, and chrysan- 

 themums are also favorite hosts. The plants in the 

 vicinity of greenhouses which are subject to the at- 

 tacks of red spiders are beans, eggplants, celery, to- 

 matoes, strawberries, clover, grasses, and weeds. 



Nature of Injury. The red spiders (fig. 76, a) 

 feed on the under side of the leaves by puncturing 

 and extracting the chlorophyll and plant juices in 

 the cells of the punctured area. This soon results 

 in small dead areas which become apparent as small 

 whitish specks on the upper part of the kaf. In 

 advanced stages, affected foliage become pale, whit- 

 ish, transparent, and covered with minute dead pitted 

 specks usually arranged in clusters. 



Control. Red spiders are at their best in hot, dry 

 houses. They may be readily controlled by syring- 

 ing with water. A strong but fine water spray de- 



365 



