314 ILLINOIS ACADEMY OF SCIENCE 



comparable to their out-door breeding situations are 

 maintained in the green-houses. 



Last fall (1919) a number of adults were found in the 

 greenhouse at the University Vivarium building, resting 

 on the sides of the small overflow troughs or channels. 

 Several times since, efforts have been made to discover 

 if the species passes the winter there and, if so, in what 

 stage. No stage has so far been discovered in this sit- 

 uation, only adults in spider's webs remaining as evi- 

 dence of their occurrence there. 



It may be seen from the above account that the gen- 

 eral features of the immature stages are quite in agree- 

 ment with other members of the tribe Limnobiini, the lar- 

 vae living in silken tubes into which they retreat when 

 danger threatens. A similar habit is found in the genera 

 Limnohia, Dicranomyia, Rhipidia, Discobola, Elliptera, 

 Antocha and others. 



The immature stages may be briefly described as fol- 

 lows : 



Larva. — Length, 12 — 12.5 mm. 

 Diameter, 0.8 — 0.9 mm. 



The living larva is graj^sh subhyaline in color, the ali- 

 mentary canal and the tracheae showing very clearly 

 through the integument; on the posterior lateral por- 

 tion of the prothorax a large orange area is evident; 

 the transverse welts on the segments dark brown. Upon 

 dropping the larvae in alcohol they soon become opaque 

 white. 



Body moderately long and slender, the thoracic seg- 

 ments gradually decreasing in lengih from the prothorax 

 to the metathorax ; first abdominal segment short, the ab- 

 dominal segments gradually elongated to the fifth, then 

 shortened to the end of the abdomen. The ventral sur- 

 face of the last two thoracic segments and the first eight 

 abdominal segments are each provided with a basal trans- 

 verse welt which is densely set with microscopic short 

 hairs or points. On the mesothorax and metathorax 

 these are broad, the spicules most dense medially to form 

 a broadly triangular region, the lateral portions with 



