Spiders and Their Near Relatives 



pests in greenhouses and in the warmer and drier regions they 

 often infest fruit trees in the open air to a serious extent. The 

 common species of the greenhouse is Teiranychus telarius (T. 

 te-la'ri-us). To this family belongs also the clover mite, Bryobia 

 pratensis (Bry-o'bi-a pra-ten'sis), which infests clover and other 

 annual plants as well as fruit trees. 



The species that infest greenhouses can be kept in check by 

 keeping the plants moist, spraying them every day. But the 

 best remedy is flowers of sulphur applied either as a dry powder 

 or as a spray. A spray of kerosene emulsion is also effective, 

 killing the eggs as well as the mites. 



The family Trombidiidae (Trom-bi-di'-i-dae) includes the well- 

 known harvest-mites. These are always red in colour, but some 

 are much darker than others. Most of the species are of moderate 

 or large size. A common species in the Eastern States, Trom- 

 bidium sericeum (Trom-bid'i-um se-ric'e-um — ) is found in moist 

 woodlands and often attracts attention by its bright red colour 

 and silky vestiture. 



In the harvest-mites the body is divided into two regions, 

 the cephalothorax and abdomen; but the so-called abdomen bears 

 the third and fourth pairs of legs. The body and legs are covered 

 either with bristles or with feathered hairs. There are two pairs 

 of lateral eyes; in many cases these are borne on pedicels. 



The six-legged larvae of some species are the "red-bugs" of 

 the Southern States that attach themselves to man, and cause 

 serious annoyance. They burrow beneath the skin and produce 

 inflamed spots. They can be killed by the use of a sulphur oint- 

 ment. The mature mite is not parasitic, but wanders about 

 feeding on small insects. 



Superfamily HYDRACHNOIDEA (Hy-drach-noi'de-a) 



The IVater-rnites 



The Hydrachnoidea includes two families, the Hydrachnidas 

 and the Halacaridae. The Halacaridae (Hal-a-car'i-dae) is a small 

 family of marine mites. The species that occur along the coasts 

 of North America have not been studied, only a single species 

 having been described; but of the Hydrachnidae about one hundred 

 North American species are known. These represent twenty-five 

 genera. 



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