UNCLASSIFIED PESTS 851 



that they find conditions most snitable for depositing their 

 eggs. 



An effective and practicable method of destroying grasshop- 

 pers is by the use of a poisoned bait made according to the 

 formuhi given on page 299. 



The Red-Spider 



Tetranychus telarius Linnaeus 



It has often been pointed out that the common name of this 

 pest is inappropriate because it is neither a spider nor is it al- 

 ways red, but as this name has been in use for many years it 

 would seem unwise to designate it as the spider mite as has 

 been suggested recently. The red-spider is a mite belonging 

 to the class Arachnida. On hatching, this mite is provided 

 with three pairs of legs but before reaching maturity acquires 

 a fourth pair. The mouth-parts are adapted for piercing the 

 epidermis of the' leaf on the juices of which the animal feeds. 

 The red-spider attacks a great variety of plants both in the 

 greenhouse and in the open. Of the former, roses, chrysan- 

 themums, violets and carnations are particularly liable to in- 

 jury while of the latter, arbor-vitae, juniper, lilac, snowball and 

 red sage should be mentioned. In the nursery some cherries 

 may be attacked. The red-spider is also an important enemy 

 of cotton and sometimes becomes troublesome on okra, cu- 

 cumber, melon, eggplant, bean, tomato, pepper, sugar-beet, 

 hops and orchard trees. Bramble fruits are especially liable 

 to attack. The red-spider is almost cosmopolitan in its dis- 

 tribution, occurring wherever suitable food plants are found 

 and being most abundant in those regions where the climate is 

 dry. The mite is usually most troublesome in seasons of 

 drought or in greenhouses where the moisture is deficient. 



The full-grown female red-spider (Fig. 221) is a little less 

 than 5^ iii<^li i^^ length; the male measures about yV inch. 



