230 



FORTt-FOURTH REPORT ON THE StATE MuSEUM 



The follo"Wing is offered as a slight contribution to the natural 

 history of Helophilus lalifrons. 



A Correction. 

 This insect was noticed in the Keport of the Entomologist for the 

 year 1885, loc. cit. sup., under the name of Helophilus similis Macquart — 

 the result of erroneous determination of the specimens in my cabinet. 



The two species bear so close a resem- 

 blance to one another that prior to the 

 detailed and comparative descriptions 

 given by Dr. Williston, examples in 

 collections were often incorrectly 

 named. The principal structural dif- 

 ference is to be found in the compara- 

 tive breadth of the front in the males; 



FIG. 2.- HELOPHILUS LATiFBONs. ^^^ ^^^^^ differeuccs as indicated by 

 enlarged. Baron Osten Sacken, are mainly colora- 



tional. A ready means of separa- 

 ting the species is offered in the 

 form of the lateral black stripes of 

 the thorax, which are less heavy in 

 latifroyis, and terminate in a point on 

 the anterior r nd posterior margins, 

 while in similis they appear to be 

 continued broadly over them. The 

 last-named species is also a stouter 

 form, having a comparatively broader Fig. 3. - Helophilus similis, enlarged, 

 thorax and abdomen. H. latifrons is represented in figure 2, and 



E. similis in figure 3. 



Habitat of the Larva. 



Examples of the larvse of H. latifrons were received in 1885, from Dr. 



R. H. Morey, of Old Chatham, N. Y., who, attracted by the singular 



appearance of their rat-tail like appendage, had taken them from a 



water-tank in Nassau, N. Y. They were numerous at the time, July 



fourth, but when a week later additional examples were asked for, 



only a half dozen could be found — all bift these having left the water 



and gone elsewhere for pupation. 



The Mature Larvae. 

 The larvae were placed in a glass of water with an inch of ground 

 and dead vegetable matter at the bottom. They hid themselves in 

 the ground, with their tails extended upward to the surface for reS' 

 piration, to an extent of two inches, except when disturbed, when the 

 respiratory tube would be quickly withdrawn from the surface and 

 partly contracted. 



