220 AN INTRODUCTION TO ENTOMOLOGY. 



Stalls. This genus includes the smaller of our representatives 

 of the family, those having an expanse of wings of about 25 mm. 

 (i in.). The prothorax is nearly or quite equal in width to the 

 head ; there are no ocelli ; the antennae are filiform ; the wings are 

 irregularly reticulated with stout veins; and the fourth segment of 

 the tarsi is dilated and bilobed. Our common species is S. in- 

 fumdta. This is black, with the head not narrowed posteriorly ; the 

 prothorax is a little wider than the head ; and the feet and wings 

 are black. I find the larva of this species common in the swiftly- 

 flowing creeks about Ithaca, adhering to the lower side of stones in 

 the bed of the streams. It resembles in form a young Corydalis, 

 or " Dobson." It has a pair of long tapering appendages on each 

 of the first seven abdominal segments, similar to those of Cory- 

 dalis. It differs from Corydalis in that the caudal end of the body 

 is terminated by a very long tapering appendage ; and there are no 

 tufts of tracheal gills. It is probable that when the larva is full 

 grown it leaves the water and transforms in an earthen cell without 

 a cocoon, as is the case with well-known European species. 



Chaullodes. The species of Chauliodes are larger than the mem- 

 bers of the preceding genus, measuring from 30-60 mm. (1.2 in.- 

 2.4 in.) in length, and having an alar expanse of from 60-100 mm. 

 (2.4 in.-4 in.). They differ also in having ocelli ; three in number, 

 and placed close together. This genus closely resembles the follow- 

 ing one, but can be distinguished by the characters given in the 

 table above. The two genera also differ in that the caudal appen- 

 dages of the male are conical and simple in Chauliodes ; while they 

 are in the form of forceps in Corydalis. The larva of Chauliodes 

 also greatly resembles that of Corydalis. The abdomen is furnished 

 with similar lateral filaments, and anal pro-legs furnished with hooks. 

 But there are no tufts of tracheal gills as in Corydalis. The larva 

 of Chauliodes are aquatic, and probably carnivorous. 



Chaullodes pecticornis is a common species with grayish wings 

 and feather-like antennae. Chauliodes serricornis is also common ; 

 this is a brownish-black species with the wings spotted with white, 

 and with serrate antennae. 



Corydalis. The characters by which this genus can be recog- 

 nized have been given in the table above, and in the discussion of 

 the preceding genus. We have but a single common species, the 

 Hellgrammite-fly, Corydalis cornuta. This is a magnificent insect, 

 having an alar expanse of from 100-135 mm. (4 in.~5.4 in.). The 

 male is remarkable for the great size of its mandibles, which are 



