REPORT ON MOSQUITOES. 41 



undoubtedly exists in soUicitans at least. I have not observed it 

 in others. 



VEGETATION AND MOSQUITOES. 



Prom the fact that mosquitoes are often found in large num- 

 bers in grasses and bushes, and are usually most troublesome 

 about porches that are vine-covered, a popular belief has devel- 

 oped that this vegetation in some way favors their breeding or 

 that they actually breed in the grass itself. 



That they breed in or among the grasses and bushes is of 

 course an erroneous belief ; but there is no doubt that such places 

 afford convenient shelter for the insects and that they rest there 

 during the day. Those that hide in the grass are usually the 

 salt marsh species ; those that seek the shelter of bushes and vines 

 are usually Culex pipiens and restuans, the species of Anopheles 

 and sometimes, C. syhestris. 



The better the hiding places, and the nearer they arfe to the 

 house, the more its inhabitants are apt to be troubled. Other 

 than as above stated there is no relation between the two. 



Coming somewhat under the same heading are the suggestions 

 that certain plants are so repugnant to mosquitoes that they will 

 not go near them and that these might be employed as repellants. 



Castor beans were once suggested and as I had usually set a 

 few of these very ornamental plants, I put out several groups of 

 them in 1902 in my front lawn and next to- the porch. They 

 were faithfully tested; but under the very plants themselves the 

 mosquitoes were a little worse than anywhere else. The offend- 

 ers were soUicitans and cantator and for these at least the castor 

 oil bean has no^ terrors. Mr. Brakeley had an almost, identical 

 experience with the South American castor bean seeds which he 

 procured to test this point. 



No other plant has been tested by me and none of the reports 

 concerning other plants have been sufficiently definite tO' make 

 experiments advisable for the present investigation. 



MOSQUITO WEATHER. 



That the character of the weather is in some direct relation to 

 the prevalence of mosquitoes is recognized by the common refer- 

 ence of a sultry, rainy period in mid-summer, as "good mosquito 

 weather." What has been already said of the breeding habits 

 of the insects explains why that should be so. Water is needed 

 for the wrigglers ; a heavy shower produces puddles and pools, 



