Sept., 1917.] Marchand: Notes on Early Stages of Chrysops. 155 



on a sheet of paper would crawl about for a short while, but an 

 hour later all had died. Efforts to bring them back to life by placing 

 them in water proved fruitless. 



Reaching the water under normal conditions', the Chrysops larvae 

 at once sink to the bottom; the lumps are dissolved and each larva 

 moves about with a slow wriggling movement. The young larvae 

 measure about i mm. in length. They are at first positively photo- 

 tropic, and the majority of them congregate on that side of the jar 

 which is turned towards the light. This tropism is reversed after 

 the first molt and it is evidently then that the larvae burrow into the 

 mud, where they seem to spend the rest of their life until pupation. 



Description of the Larva of C. callidus. 



The young larvae were placed in small glass jars with a small 

 quantity of mud and aquatic plants. Young crushed dragonfly and 

 Chironomus larvae were given as food. Their growth, however, was 

 very slow and I did not succeed in keeping them alive much longer 

 than after the first molt. This was partly due to the difificulty of 

 furnishing them a suitable food supply and at the same time keeping 

 the water pure and rich in oxygen, as the pretence of decaying ma- 

 terial seems fatal. I will, however, give here a description of the 

 young larvae, as they have never been described in any species of 

 Chrysops. Concerning the larval stages of this genus, we had up to 

 very recently only the description of the full-grown larva of Chrysops 

 vittatus, by C. W. Hart (1895). It will be seen that even the very 

 young larvae of Chrysops show very marked peculiarities which per- 

 mit us to differentiate them from young larvae of Tahanus, at least 

 those which I had under observation. 



All Tabanid larvae are, as we know well, comparatively uniform 

 in structure, hence repetition in description is to some extent in- 

 evitable. The young larvae of Chrysops callidus are about i mm. in 

 length, elongate, tapering at both ends, with tracheae not yet filled with 

 air and prolegs not exserted, consequently presenting a more or less 

 even surface. Their color is grayish white (Plate X, fig. 4). The 

 body has twelve segments, the head is small, pointed, blackish brown 

 in color and highly chitinized. The prolegs or parapodia are visible 

 as small knobs on the fourth, fifth, sixth, seventh, eighth, ninth, and 



