REPORT OX MOSQUITOES. 479 



The woodland areas often breed many mosquitoes, mainly of 

 the species of Ciilex sylvestris, but more often are clean and safe. 

 Several times in the spring and again in the fall, the whole terri- 

 tory is flooded by the rising waters of the Passaic River and at 

 such times breeding is at a standstill. Then, in the summer, the 

 majority of the places dry up completely, again suspending the 

 development of larvae. 



This shows that the mosquito breeding periods are very un- 

 certain and depend wholly upon favorable conditions. 



The adults are rather long lived, as is stated in another part of 

 this report, and find shelter in wooded districts, until suitable 

 places are found to deposit eggs ; the eggs do not hatch until 

 other favoring conditions set in, so the mosquito breeding is de- 

 layed in one stage or other, occasionally for long periods of 

 time. Thus, after a long spell of rain that fills the pools but does 

 not flood the meadow, mosquitoes will breed by millions, and 

 when these pools dry up and eggs are laid in the mud, the eggs 

 will not hatch until again covered with water, which may not be 

 very soon. 



There are two distinct kinds of places where mosquitoes breed 

 in the Passaic Valley region, and each breeds its own species, 

 first : the woodland areas referred to above and, second : the 

 grassy areas. These areas irregularly intercept each other and 

 are usually small in extent though, sometimes, they are very 

 large. 



The woodland areas are often flooded and at such times no 

 larvae are found; but when the water subsides millions of larvae 

 breed in the pools which have formed in the depressions. The 

 abundant form is always Culex sylvestris; but Culex canadensis 

 in the spring and Janthinosoma iniisica in the latter part of the 

 summer, also breed in some numbers. 



In times of drought many of the larvae or even an entire brood 

 die through evaporation of the pools, and at other times they 

 are drifted away by the rising waters ; but usually a brood once 

 started has time to mature, as a week in most cases is sufficient.. 



Adult mosquitoes are almost always present in large numbers 

 in these woodlands and it is surprising to see what a large num- 

 ber are strictly salt marsh forms — Cidex cantator and sollicitans. 



In the grassy areas breeding is comparatively rare ; water is 

 almost aways present and covers the entire surface, i. e.. it is not 

 collected into pools. Fish rarely, if ever, get in these j^laces. for 

 the vegetation is too dense; but water insects are numerous and 

 to a certain extent keep down mosquito life. Where water 

 beetles were very plentiful, larvae were never found. 



