EXPERIMENT STATION EErORT. 641 



one patcli of woods to another^ but even a \aide road throiigii the 

 woods would be freely crossed at night, though no mosquitoes 

 would be found on it during the day. 



A few of these pot holes may be easily and i-lieajjly drained, and 

 that Avill be the best way of getting rid of such. A great many of 

 them can be easily filled with soil from the surrounding hillocks. 

 There will remain a consideral)le number tliat cannot be easily 

 drained and which it would be rather expen^avfi to fill in the ordi- 

 nary way. These would have to be dealt with l)y oiling or by mak- 

 ing them unsttitable for mosqtiito breeding. Oiling is usually an 

 tmsatisfactory makeshift and not to be reecanmonded, and yet it 

 deser\'es consideration in this connection berause it would have to 

 be done once only. Xone of the sylvan specie^ f xcept C. canadensis 

 have more than one brood, and this matures in late April or early 

 May — usually the latter. A couple of men with knapsack sprayers 

 and a supply wagon could cover a A^ery large area in one day and 

 could oil-cover the pools in it so' thoroughly that, few larvae could 

 come to maturity. Done once, the task wovild lie finished for the 

 season, and each year would make it easier, since persistent thor- 

 ough work results in practical extermination in all the easily acces- 

 sible pools. The matter is worth careful consideration. 



To render the pools unfit for breeding places would mean to 

 cover them in such a way as to prevent the larva from getting free 

 access to the air. These pot holes are natural sinks into which the 

 water drains from the surroimding slopes, but while the hole may 

 be inevitable, it need not remain freely open, to mosquitoes. It 

 could be loosely filled with stones and boulders, over which logs 

 and branches could be ]>iled in such a way as to foi-m a rather solid 

 covering to the pool so dense as to make it uninviting as a breeding 

 jDlace. Mosqtiitoes do not like too much shaxUi, and even a filling 

 with branches of trees cut into short lengths would be sufficient in 

 many instances. This would cost more than oiling, but would be 

 more permanent, though it would have to be looked over at inter- 

 vals of two or three years. 



As to the other breeding places for sylvesfris and its companions, 

 a few intelligently-placed ditches, a little filling and a few culverts 

 or pipes across roads will be nearly all that is necessary. 



41 



