60 DRAGOISr FLIES VS. MOSQUITOES. 



to ^vhicll Riley, Packard, and Thomas ^^^ have given some 

 attention in the case of other insects. 



The ranltiplication of electric lights may hold forth 

 some promises, as nrged by some writers, though we be- 

 lieve that neither Culex nor Musca is likely to be greatly 

 decreased by this method. 



Having discussed those insecticides which are generally 

 applicable to this work of extermination, we come now to 

 more specific considerations, to be taken up in detail. 



The Culicidse are much more vulnerable in their larval 

 state, and a consideration, of their early stages yields sev- 

 eral new points. The means for extermination may be 

 divided into natural and artificial insecticides and destruc- 

 tive methods. Under the former may be classed all 

 chemical or animal enemies, aquatic Hemiptera and Co- 

 leoptera, fish, Odonata larvae, etc. Of the latter class, 

 flushing the breeding places with water, draining swamps^ 

 and creating active artificial currents may be mentioned. 

 Aquatic predatory insects may be dismissed at once ; while 

 such have been observed to be inimical to the Odonata 

 while in their earliest stages, such genera as Notonecta, 

 Ranatra, Geoifria, et al., do not bother themselves with the 

 slender Culicidte, which lacks substance and pulpiness. 



Fish are active and untiring in their efforts to thin out 

 the Culicid ranks. A small sunfish taken from our 

 aquarium and put into one of our many tanks of water 

 well filled with these larvte, had soon to be removed, as he 

 reduced the ranks too rapidly. Unfortunately it is sel- 

 dom that fish can be utilized, as Culex usually selects for 

 oviposition those pools and stagnant ponds where fish can- 

 not live. Where the breeding ponds or marshes are near 

 the seashore or inland bays, flushing these pest holes will 



