244 THE MOSQUITOES OF NEW JERSEY 



Examination of the gut contents of larvae, brought into the laboratory 

 directly from the pools, gave some interesting indications of what they 

 really lived on. Results of a few examinations will suffice as examples. 



"Number 23. Gut contents of two larvae. Protozoa : Euglypha, 

 Trinema, Trachelomonas, Arcella, Chlamydomonas, Euglena. Plants: 

 Fungus spores, zygospores of an alga, a few diatoms ; there was also 

 a cyst of what was probably a ciliate. Most of the food, however, was 

 Trachelomonas and the algal spore. No oil was present in the gut and 

 but little in the larvae. 



"Number 20. The gut contents of two larvae showed that they had 

 eaten heavily of Daphnia, which were numerous in the water, but had, 

 perhaps, eaten the dead and disintegrating Copepods, for the living 

 ones were clearly too large for a mouthful. The gut contents showed 

 also some black mud and huge quantities of a well digested alga, appar- 

 ently Tribonema. Some few diatoms and specimens of Phacus, along 

 with an organism somewhat like Chlamydomonas, completed the menu. 

 Not many protozoa were present in the water in which these larvae lived. 



"Number 32. These larvae had practically nothing in their intestines 

 but Trachelomonas, which organism was most abundant in the water. 



"These examples show that the larvae (all A. canadensis) lived on 

 the animals and plants as they occurred in the water. In the case of 

 Number 23 the diet was mixed, including protozoa and algae; in the 

 case of Number 20, they fed mostly on algae, whereas in the case of 

 Number 32 practically nothing but a protozoa was devoured. 



"We notice from Tables VII and VIII that, in the pool in Union 

 County, where no breeding was expected, during the middle of March 

 enough food was present to support larvae for a short time. This food 

 supply decreased until, in the beginning of August, the water was al- 

 most sterile. Up to this time, some larvae of a little fly, Corethra sp., 

 were found. In the second part of August the food supply increased 

 somewhat and the larvae of a non-biting mosquito, Uranotaenia sap- 

 phirina, were found. These occurred when the chloride content de- 

 creased markedly. They disappeared again, coinciding with a consider- 

 able increase of chloride and sulfate content, due apparently to rains 

 causing street washings from the concrete road to flow into the pond. 

 On September 15, when the chloride content was lowest and the food 

 supply had increased, larvae of C. pipiens and Anopheles species were 

 taken. The week in September, when chlorides had increased again but 

 all sulfates disappeared, larvae were still present. During the entire 

 season sulfates were comparatively high in this water. Every time, when 

 these comparatively large quantities of sulfates were present, a strong 



