[129] 



COLLECTING AND PEESERVING INSECTS RILEY. 



crawl under the shelter afforded by holes in the earth or under sticks. 

 Here, in the course of two or three weeks, they transform within the 



riG. 137 .—Trombidium locustarum . a, mature larva when about to leave the wing of a locust ; 6, 

 pupa; c, male adult when just from the pupa; d, female — the natural sizes indicated to the right; 

 •e, palpal claw and thiunb ; /, pedal claw ; (j, one of the barbed hairs ; h, the striations on the larval 

 skin. 



larval skin to the pupal stage shown at h, and eventually break through 



the old larval skin and escape in the form shown at c and d. This 



mature form passes the winter in the ground and is active whenever 



the temperature is a few degrees above the freezing point. A larger 



species T. giganteum Eiley, also attacks 



locusts, while a third species attacks the 



common House-fly. This was formerly 



known in the larva state only and was 



referred to the genus Astoma, to which 



also the larval form of Trombidium was 



referred. I have described the adult 



together with the larva and pupa as 



Tromhidium muscarum. An allied mite, 



Hydraclma helostomw, attacks the large 



aquatic water bug, Belostoma, and has a 



mode of development precisely similar 



to that of Trombidium. 



To this family also belong the common 

 greenhouse mite, Tetranychus telarius, 

 and also the Bryobia mite, B. pratensis, 

 which of late years has attracted very 

 considerable attention by its appearance 

 in immense numbers about dwellings, 

 coming from the adjoining fields of 

 clover or grass. Generically allied to the 

 greenhouse mite is the Six-spotted Mite 

 of the Orange (T. 6-maeulatus Eiley), which is shown in the accom- 

 panying figure. 

 2564 9 



Pig. 138. — The Six-spotted Mite of the 

 Orange (Tetranychus B-inacidatus) : o, 

 from above — enlarged ; ^- tarsus ; c, ros- 

 trum and palpus — still more enlarged; 

 d, tip of palpus — still more enlarged. 



