89 



been inspired bj' a desire to reduce the numbers of these pests, to 

 make habitalile at certain seasons of the year large areas that may be 

 devoted to a variety of enterprises, and to check the spread of dis- 

 eases, our studies were beg^un with the idea of assisting as far as pos- 

 sible in this laudable cause, and we trust that some of the facts as set 

 forth in this paper ma}' prove of value in future work upon this 

 subject. 



The mosquito genera that have come under our observations are 

 Stegoniyia, Culex^ Co7ichyllates, P><oropli(ym^ and Anopheles^ and as 

 many as 2-1: species have been studied more or less. We had expected 

 to discuss our observations upon all the species common to Baton 

 Rouge and vicinity, but it would take more time than that usually 

 allotted to the discussion of a single topic on occasions like this. We 

 have, therefore, thought best to discuss in a general way the problems 

 associated with the hibernation and development of mosquitoes as a 

 whole and to discuss in detail, though briefly, the life cycle of Psoro- 

 phoia. 



The time required for the transformation of mosquitoes, as with 

 most insects, is decidedly a variable quantity, dependent upon food 

 and temperature conditions, and thus statements of so-called normal 

 life of mosquitoes are misleading unless accompanied b}^ the exact 

 conditions under which this information was procured. While with 

 most students of insect development, a knowledge of conditions is 

 assumed, yet public sentiment, upon which science is more or less 

 dependent for the operation of remedial measures, is seldom conver- 

 sant with details of conditions, and if remedies fail much time is lost 

 in explaining the reasons why failure occurred. 



RESULTS OF OBSERVATIONS ON MOSQUITOES. 



From our studies of mosquitoes in general we have observed the 

 foUoAving: 



Flnt. That local pools are common breeding grounds for most spe- 

 cies of mosquitoes. Of the 24 species found here every one has, in 

 some stage of its development, been taken from a small pond 10 feet 

 long, 4 feet wide, and of that depth that two weeks' drought was suffi- 

 cient to evaporate all the water it contained. The lack of enemies of 

 mosquitoes in such places may largely be responsible for the prevalence 

 of such a variety of forms of variable life histor}^ 



Secovd. That most mosquitoes deposit eggs singly upon the surface 

 of the water (exceptions are Culex pipien^s^ C. con^^ohrinuH^ and possi- 

 bly one or two other species) and, except in the cases of Anopheles and 

 those placed in boat masses, the majority will sink to the bottom of 

 ponds or breeding vessels. 



Third. That the sinking of eggs and low temperature, as well as the 

 rapid evaporation of the water of pools on which eggs are laid, produce 



