180 



Forty- fifth Report on the State Museum. 



vice — at times, of almost incalculable value — in the destruction of 

 the eggs of the western locusts (commonly called grasshoppers), which 

 it seeks when buried in the ground and eagerly devours. The young 

 mites are very active little creatures, living at first in the ground where 

 they feed on decaying animal and vegetable substances. When the 

 opportunity is given them, they crawl upon the bodies of the locusts 



Fig. 

 locust 

 g, one 



C w a 



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

 ; 6, pupa; c, male adult; d, female adult; e, palpal claw and thumb; /, pedal claws; 

 of the barbed hairs; h, the striations on the larval skin. (After Riley.) 



and attach themselves, in preference beneath the base of the wings, but 

 sometimes, when unusually abundant, covering the entire body. While 

 upon the locust, they are immature, being in their larval stage, and 

 having only six legs. As they gorge themselves with the juices of 

 their host, their bodies swell out into an oval sack-like form, almost 

 concealing the legs, although they are long, and in this condition [rep- 

 resented at a in the figure] they may very easily be mistaken, as in the 

 above inquiry, for eggs. After they have completed their larval 

 growth they drop to the ground, where they undergo two changes — 

 first to the pupa [shown at b in the figure] and then to the perfect 

 eight-legged form [shown at c and d~\. They pass the winter in the 

 ground, and are said to be active whenever the temperature is a few 

 degrees above the freezing. 



A detailed and interesting article on this mite from the pen of 

 Professor Riley, from Avhich the above facts and figures have been 

 taken, is to be found in the First Annual Report of the United States 

 Entomological Commission, -pages 306-311. 



This mite is not confined to the Central or Western States, but has 

 been observed in New Hampshire preying in very large numbers, both 

 on the eggs and the mature insect of the lesser locust, Melanoplus 

 atlanis (Riley).* 



♦Marlett, in Insect Life, ii, 1889, pp. 67, 68. 



