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REPORT OF STATE GEOLOGIST. 



male soon deposits 300 or more small, globular eggs at a depth of a 

 few inches in the soil. From each of these eggs there hatches, about 

 the time the young locusts appear, a minute six-legged mite, which 

 runs actively about in search of some host to which it may attach 

 itself. When it happens upon a young locust, it fastens itself to the 

 wings, wing pads or abdomen and uses its mouth parts to suck up 

 the fluid portions of its host. In a short time its body increases in 

 size, the legs grow smaller, and the mite resembles a small, globular 

 mass of blood attached to the locust. Sometimes as many as twenty 

 mites can be counted on a single host. When thus infested, the lo- 

 cust often becomes disabled, and drags itself about in a clumsy fash- 

 ion, eats less and dies early, often before the mating and egg-laying 

 season has arrived. In the swollen and almost legless condition 

 which the mite soon attains, it can not move about, and so remains 

 in one position until full grown, when it drops to the ground 

 and enters the pupal stage from which it emerges as the "red spider- 

 kin" of spring. It often becomes mature in late autumn and passes 



Fig. 17. Trombidium locustarum.—a, mature larva when about to leave the wing of a 

 locust; ?<, pupa; c, male adult when just from the pupa; J, female— the natural sizes indi; 

 cated to the right; e, pupal claw and thumb; /, pedal claws; g, one of the barbed hairs 

 h, the striations on the larval skin. (Aftsr Riley.) 



the winter in the ground where it is not idle, except when the tem- 

 perature sinks below the freezing point. It feeds upon all sorts of 

 soft food, and whenever it has access to the eggs of locusts it greedily 

 eats them. In soil containing eggs of locusts large numbers of these 

 mites congregate. They creep into every hole in search of these eggs 

 and thrive upon such rich food. The great advantage of fall plow- 

 ing over all other remedies against locusts is seen in regard to these 

 red mites, as the plowing of fields in which the eggs of locusts have 

 been deposited will destroy the young locusts hatching from them, 



