Proceedings of Sixth Annual Meeting 69 



The Mosquito Control Problem on the New Jersey Side of 

 the Delaware River from Penns Grove to Qloudester 



BY MITCHEL CARROLL, PH.D., ASST. ENTOMOLOGIST, N. J. AGL. 



EXPT. STA. 



During March, 1918, in response to a demand for protection from 

 the mosquito pest for the war industries along the Delaware River, 

 the speaker made an inspection of the area from Camden to Penns 

 Grove and extending back from 3 to 6 miles from the river. The 

 figures and estimates hereinafter given are based on this inspection. 



The residents throughout this region report mosquitoes very- 

 troublesome in the evenings and at night. Except in the marshes, 

 themselves, they are not troubled by mosquitoes during the day, 

 unless the weather is damp and cloudy. In the latter case, es- 

 pecially if the wind be from the direction of large swamps, mos- 

 quitoes are reported often present in large numbers at some places 

 even during the day. From Big Timber Creek south to Oldman's 

 Creek, sylvestris seems to be the prevailing species. Residents 

 everywhere in this district describe the common mosquito as a 

 small species with white spots on its back. At intervals most 

 places in this region are subject also to invasions from a large 

 brown mosquito. The latter is usually described as a fierce biter, 

 leaving a much larger swelling about the wound than the smaller 

 species. It is possible that this large mosquito may be in some 

 cases Mansonia perturbans Wlk., and in others Aedes suhcantans 

 Felt. And in the southern part of the region under discussion, 

 Aedes sollicitans Wlk., and Aedes cantator Coq., may occur as 

 migrants from the salt marshes down the bay. 



It does not seem probable that any salt marsh species breed in 

 the above area, as the salinity of the river water at Chester Island 

 (in March) is only about 3 per cent. Nor could any reliable re- 

 ports of the presence of Anophelines be obtained. At the Gibbs- 

 town plant of the Dupont Powder Company, 4 or 5 cases of malaria 

 appeared during the summer of 1917, but only 2 of these showed the 

 parasite in the blood, and all had come from the tropics. 



Psorophora ciliata Fabr., occurs at several places along the Dela- 

 ware. A mosquito described by employees of the New Jersey 

 Shipbuilding Company at the mouth of Big Timber Creek, and by 

 a fisherman at the mouth of Mantua Creek, was evidently this 

 species. , 



