SB 



° -L ° No. 13, Second Series. 



C578 



ENT lited States Department of Agriculture, 



DIVISION OP^ ENTOMOLOGY. 



MOSQUITOES AND FLEAS. 



I. — MOSQUITOES. 



We are accustomed to think of but a single species of mosquito, and 

 of this as occurring in most parts of the countr}^ but as a matter of fact 

 Osten Sacken's Catalogue of the Diptera records twenty-one species from 

 North America, and Mr. F. W. Urich states that he has observed at 

 least ten species in Trinidad. Twenty species are contained in the 

 collection of the U. S. National Museum. 



The following statement concerning the life histor}' of these insects is 

 based upon a series of observations made in this Division upon the 

 development of two summer generations of Gnlex pungens^ one of our 

 commonest and most widespread species. The writer has seen speci- 

 mens of this insect from New Hampshire, Massachusetts, New York, 

 Maryland, District of Columbia, Illinois, Minnesota, Kentucky, Nebraska, 

 'Louisiana, (leorgia, and the Island of Jamaica, West Indies. No doubt 

 it is also abundant in New Jersej'. 



Egg-laying takes place at night. The eggs are deposited in boat- 

 shaped masses on the surface of the water, the number varying from 

 200 to 400 in each mass. The eggs may hatch in sixteen hours. The 

 larvae live beneath the surface of the water, coming to the top at fre- 

 quent intervals to breathe. The larval state may be completed in seven 

 daj's; the pupal state ma}- last only twenty-four hours. An entire gen- 

 eration in summer time, then, may be completed in ten days. This 

 length of time, however, may be almost indefinitely enlarged if the 

 weather be cool. There are, therefore, man}'' generations in the course 

 of a season and the insect may breed successfully in a more or less 

 transient surface pool of water. 



Mosquitoes hibernate in the adult condition in cellars and outhouses 

 and under all sorts of shelter. The degree of cold makes no difference 

 in successful hibernation ; mosquitoes are alnmdant in the arctic regions. 



REMEDIES. 



Of remedies against mosquitoes in houses the best is a thorough 

 screening of windov.'s and the placing of nets about beds. If the insects 

 are troublesome in sitting or sleeping rooms during the evening, the 

 burning of pyrethrum will so stupefy them as to make their presence 

 unobjectionable. Pyrethrum for this purpose should be prepared bj' 

 moistening the powder suflicientlj' to allow of its being roughly molded 

 by hand into little cones about the size and shape of a large chocolate 

 drop. These cones are then placed in a pan and thoroughl}- dried in 

 an oven. When fired at the apex, such a cone will smoulder slowly, 

 and send up a thin column of pungent smoke, not hurtful to man, but 

 stupefying to mosquitoes. In actual experience two or three such cones 

 burned during the course of an evening have given much relief from 

 mosquitoes in sitting rooms. It does not kill the insects, however, and 

 is at best but a palliative. 



