462 



bottom of the well. That these larvae, having haemoglobin in the 

 blood, are, by its presence, adapted to living in deep water is a gener- 

 ally accepted view, but one difficult to reconcile with the fact that as- 

 sociated with these larvae at great depths, and under anaerobic condi- 

 tions are to be found larvae of other species which presumably have no 

 haemoglobin in the blood since they are either whitish or greenish in 

 color instead of red. It is also well known to students of the group 

 that many of the blood-red species occur in puddles and shallow pools 

 and streams. In commenting on Mr. Gahan's report "Dr. Dyar said 

 that the presence of the larvae in the well was probably induced by the 

 wooden walls, which would furnish food. He thought no larvae 

 would be found in the wells entirely lined with stone, as is ordinarily 

 the case."* As previously stated, the larvae of this group of species 

 live upon algae and diatoms, and occur in wells or reservoirs the sides 

 of which are of stone or concrete. 



A. C. Burrill has referred to the "green specks" exuded by imag- 

 inal Chironomidcc, and raises the question as to whether the color of 

 these is due to their having fed upon green algal matter in the "pre- 

 pupal" stage, t It may be pertinent to indicate that imagines of all orders, 

 as far as is known to the writer, after attaining full expansion of wings 

 and a degree of maturity that enables them to take flight, exude a cer- 

 tain amount of fluid that as a general rule partakes of the same gen- 

 eral color as the insect. Students of Lepidoptera in particular must be 

 well aware of this fact, and know that while in some species the color 

 of the fluid is red in others it is white, or even greenish. The well- 

 known reports of "showers of blood" in the Mediterranean region 

 have been traced to the simultaneous emergence of large numbers of 

 Vanessidcc, and other Lepidoptera, following a shower of rain which 

 provided the required conditions for that emergence. It is thus not 

 only a probability but a fact that the green specks referred to by Bur- 

 rill partake of this same nature. In the case of the specimens reared 

 by the writer from the city water of Champaign the green exudations 

 were very pronounced, though green algae could have formed but a 

 very small portion, if any, of the food of the larvae. 



An attempt was made by the writer to ascertain how long the 

 imagines of viridicollis would live under laboratory conditions. Upon 

 emergence the imagines were placed in one-ounce bottles, which were 

 corked and laid close to a window where they would be least subject to 

 the indoor conditions. The room was kept, by means of automatic 

 heaters, at a fairly even temperature of 70 to 75 degrees F., but the 



*Loc. cit., pp. 104-105. 



iBull. Wis. Nat. Hist. Soc, Yol. X, 1913, p. 139. 



