34 ILLINOIS NATURAL HISTORY SURVEY CIRCULAR 39 



common species is Reticulitermes flavipes (Kollar), fig. 24, which 

 is destructive to buildings of wooden construction throughout 

 Illinois ; it is most destructive in the southern part of the state. 



Plecoptera Insects that pass the young or nymphal stage 



Stoneflies in streams. They have slender, soft bodies, 



long antennae, long legs, and two long tails, 

 and they move about rapidly. The adults are terrestrial in habit 

 and occur along streams. Most of them have two pairs of wings, 

 which are folded flat over the back; the number of crossveins 

 varies from many to few. The antennae are long, the mouth- 

 parts of chewing type but very reduced. Of exceptional interest 



Fig. 25. — Plecoptera. Isoperla confusa, one 

 of the typical stoneflies found in Illinois; 

 adult form. Actual length about 0.8 inch. 

 Illinois stoneflies range in length from 0.25 

 inch to 1.5 inches. 



Fig. 26. — Plecoptera. Iso- 

 perla confusa; the nymph of 

 the species shown in fig. 25. 

 The nymph lives in streams. 

 Actual length about 0.6 inch. 



