tNJURIOUS AND BENEFICIAL [NSECTS OK CALIFORNIA. 



ARACHNIDA (Class) 



SCORPIONS, SPIDERS AND MITES 



Because of their economic importance, we have thought it best to 

 include here the common injurious mites of California, even though 

 they are not insects. As pointed out in the general classification, 

 mites usually have eight legs and have the head and thorax united. 

 ►Some species, however, especially 

 the blister-mites, have only four 

 legs, while the young red spiders 

 have six legs until after the first 

 molt. 



All forms feed by piercing the 

 plant tissues and extracting the 

 juice. They multiply very rap- 

 idly and are thus capable of much 

 damage. 



The winters are passed in 

 either the adult or egg stages 

 under the scales of the bark, on 

 the small limbs, around the buds 

 or under the bud scales. As soon 

 as the first leaves appear in the 

 spring the mites begin work. The 

 eggs are laid singly on the out- 

 side or inside of the plant tissues, 

 or in clusters upon the bark ; in 

 the latter case they may be de- 

 posited around the buds, some 

 time before these begin to open. 

 The young develop very rapidly 

 and are soon capable of bringing 

 forth new broods. The breeding 

 continues throughout the summer— the greatest number of mites 

 being evident during the hottest and dryest weather. Cold, damp 

 weather seems to retard all activities. 



Fig. 2. — A scorpion, Vejovis boreus 

 Girard, which is found in the southern 



part of the State. (Original) 



THE RUST MITE OF THE ORANGE AND THE SILVER MITE OF 



THE LEMON 



Eriophyes oleivorus (Ashmead) (Family Eriophyidse) 



( I'hi/toptus oleworui Ashmead) 



(Figs. 3, 4) 



Description. — The adult mites are so small as to be invisible except 

 with the aid of a lens. They are light yellow in color, long and pointed 

 anteriorly, with two pairs of legs near the head. The eggs are exceed- 

 ingly small, circular and faintly yellow in color. The presence of the 

 mite is easily told by the characteristic silvery chafing of the skin of 

 the lemon, due to the destruction of the oil cells. In Florida the 

 oranges are also chafed, causing a russeting. 



Life History.— The eggs are deposited singly or in small clusters on 

 the leaves or fruit. They hatch in less than a week in hot weather, 

 but require twice as long in cold weather. After several molls the 



