284 MOSQUITOES OF NORTH AMERICA 



upon the human species is undoubtedly of ancient development. The preference 

 for human blood is well demonstrated, and, as has been pointed out, the work 

 done by several investigators seems to prove that calopus does not oviposit until 

 aft^r having had a meal of human blood. Although Goeldi has shown oviposition 

 after a meal of guinea-pig blood, he considers human blood more efficacious 

 in bringing about ovulation. 



We have already demonstrated that calopus is essentially a town mosquito. 

 The larv£e are found practically exclusively in artificial receptacles about human 

 habitations. It may be said that the larvae of calopus are never found in swamps, 

 in pools or in temporary puddles, even when these are in close proximity to 

 houses. Durham, who studied the species at Para, makes the following state- 

 ment concerning the breeding-places. " Casual water in vessels, etc., in and 

 about houses such as buckets, tins, washtubs, rain gutters, ant-guards (per- 

 forated troughs to protect plants in gardens, and sugar, etc. in houses), larger 

 and deeper collections of water as casks or hogsheads full of rain water. Also 

 in bilge water of barges, lighters, and S. S. Viking (Amazon Telegraph Go's 

 ship, many years on the river) . Not found in sewage collections as cesspools, 

 stable runnings, etc., although found in neighbourhood in cleaner waters. Also 

 not found in natural puddles in forest or streets, etc." We are well aware that 

 there are a number of records of calopus larvae occurring in street puddles and 

 in swamps, but it would seem that in these cases the larvae were not bred and 

 most probably they were those of some other species of Aedes, many of which 

 greatly resemble calopus in general appearance. 



In the tropics the large earthen jars in which drinking water is kept are the 

 most frequent and unfailing habitat of the larva. Rain-water barrels are abun- 

 dant breeding-places. In New Orleans and other southern cities, like Galveston 

 and Mobile, rain-water tanks, so abundant behind the houses, are probably the 

 source of the most abundant supplies of these mosquitoes. Eeed and Carroll 

 state that in their search for the larva of this insect in Cuba they found them 

 in the following places: " (1) In rain-water barrels; (2) in sagging gutters 

 containing rain water; (3) in tin cans that had been used for removing excreta 

 and which still contained a small amount of fecal matter; (4) in cesspools; (5) 

 in tin cans placed about table legs to prevent the inroads of red ants ; (6) in the 

 collection of water at the base of the leaves of the agave americana; (7) in one 

 end of a horse trough that was in daily use." 



In New Orleans, in the epidemic of 1905, water-closet tanks were found to be 

 abundant breeding-places, and Surgeon White suggested that an ordinance be 

 made and enforced to cover these tanks with wire gauze. They were also found 

 breeding in the accumulation of water in the drain traps of stationary wash- 

 stands. Eoof gutters, in New Orleans, were especially noticed on a number 

 of occasions, where they sagged, to contain large numbers of calopus larvae. 

 Another interesting place where they were found breeding was in the urns in the 

 cemeteries. In the autumn of 1905, at New Orleans, Surgeon Richardson, of 

 the Public Health and Marine-Hospital Service, told one of the writers 

 (Howard) that at Laredo, Texas, in the outbreak of 1903, calopus was found 



