9 



E ~50. UNITED STATES DEPARTMENT OF AGRICULTURE. 



BUREAU OF ENTOMOLOGY, 



WASHINtJTON. D. C. ^' / 



FOREST ENTOMOLOGY. IS 



May 12, 1916 



Brief Information on the 

 RED SPIDER and ITS CONTROL. 



Character and Extent of Damage.- During a protracted drought the red spider 



is likely to become very injurious, attacking a great variety of plants* Whole 

 trees, especially seedlings and nursery stock, are apt to have their foliage 

 killed by it. 



Evidence of Infestation. - Pale, brownish spots which may later cover the fol- 

 iage cf the entire plant and a web sometimes so dense as to be plainly visible 

 at a considerable distance appear on the leaves. On examination with a magni- 

 fying lens the affected leaves are found bearing numerous, tiny, pearl-like 

 eggs, brownish or reddish little creatures running about, or the glistening 

 empty egg shells and cast skins of the mites. 



Seasonal History and Habits. - "Red spider" is the name most often applied to 

 two species of web-spinning mites. Mites differ from true insects in having 

 four pairs of legs in the adult stage. They pass the winter as adult females 

 on various wild plants. In the spring they ascend plants and start egg laying 

 at the rate of 5 to 10 eggs per day for a period of 8 tc 12 days. During hot, 

 dry weather the eggs hatch, in about 4 days after having been laid, into young 

 mites which commence feeding almost immediately. They reach maturity in 10 to 

 14 days after hatching, depending on the season and locality. Many generations 

 follow one another in course of one summer. Usually, by the time their pres- 

 ence is discovered they are already very numerous. They live and feed in 

 colonies and their feeding consists in sucking the juices from leaves. 



Remedies . - 



A stiff stream of water, frequently applied, will rid plants of red spider 

 in many cases. 



Individual trees of the kinds that expose most of both surfaces of their 

 leaves to the sun, dust with powdered sulphur. 

 Flour paste prepared as follows; 



(Small quantity). Oook § lb. of flour in 1 qt. of water until it 

 becomes a uniform paste, then pour into 2-3 galls, of water, 

 (Large quantity). 8 galls, of paste (1 lb. flour to 1 gall, water) 

 to 100 galls, of waxer. 

 Spray with tin atomizer or power pump, depending on area to be treated. 

 Make at least two applications with a 7-day interval between them. 



A. D. HOPKINS, 



Forest Entomologist. 



