ORTHOrTERA OP INDIANA. 



143 



Upon the character of the whiter of any year depends largely the 

 number of Orthoptera and other insects which will he present the 

 next summer. Most insects pass the winter in either the egg or the 

 pupal stage; since these forms can, readily withstand long and severe 

 cold weather, in fact may he frozen solid for weeks and retain life 

 and vigor, both of which are shown when warm weather and food 

 appear again. Indeed, it is not an unusually cold winter, but one of 

 successive thawings and freezings, which is most destructive to in- 

 sect life. A mild winter encourages the growth of mold which at- 

 tacks the hibernating larvee and pupge as soon as, from excess of rain 

 or humidity, they become sickly; and it also permits the continued 

 activity of insectivorous mammals and birds. Thus, moles, shrews, 

 and field mice, instead of burying themselves deeply in the ground, 

 run about freely during an open winter and destroy enormous num- 

 bers of pupge; while such birds as the woodpeckers, titmice and chick- 

 adees are constantly on the alert, and searching in every crevice and 

 cranny of fence and bark of tree for the hibernating eggs and larvae. 



Animal Parasites. — A number of parasites belonging to the ani- 

 mal kingdom use as their chief hosts the bodies of locusts and other 

 members of the order Orthoptera. Chief among these animal para- 

 sites is the red locust mite, Tromhidium locustarum Eiley. On the 

 first warm, sunny days of spring, as soon as the surface of the earth 

 is fairly dry and warm, scores of minute "red spiders" can be seen 



Fig. 16. Tromhidium locustarum.— a, female with her batch of eggs (after Emerton); 6, 



newly hatched larva, natural size indicated by the dot within the circle; c, egg; 



d, e, vacated egg shells. (After Riley.) 



along any pathway in the woods and fields. They are especially 

 common if locusts were abundant 'the year before. These red spiders 

 are in fact mature red mites, the two sexes of which are shown in 

 Fig. 17. Soon after appearing in spring, the sexes mate and the fe- 



