176 MOSQUITOES OF NORTH AMERICA 



spiders are among the most important enemies of mosquitoes. Spiders are very 

 abundant in these swamps and Doctor Leon states that enoimous numbers of 

 mosquitoes are caught in their nets and killed. Different species of spiders 

 weave their webs on sedges, reeds and willows and it is not rare to find as many as 

 twenty webs on one willow. Sometimes the number of webs is so great that they 

 become continuous and completely enwrap the tree and one can conceive the 

 large numbers of mosquitoes that can be caught in such webs. 



Mr. W. L. McAtee recently made an observation in Arkansas which is at 

 variance with those already given and which indicates the necessity for more 

 careful observations. 



" On a rainy day a large number of Anopheles quadrimaculatus were found 

 sitting on a spider web in a hollow tree. Thinking they must be at least slightly 

 entangled, I counted on capturing them easily. Upon putting my cyanide bottle 

 near one, the whole swarm rose lightly on the wing, not sticking to the web at 

 all. By further tests I found that they were perfectly at home on the web." 



OTHER ARTHROPODS. 

 Doctor Dupree once stated in a letter that he was satisfied that small crayfish 

 and fresh-water shrimps kill the larvae of mosquitoes. Britton has shown that 

 salt-water shrimps (species not mentioned) will eat the larvae of the salt-marsh 

 mosquitoes but thinks that their structure and small capacity prevent them from 

 consuming any great numbers. 



BATRACHIANS. 



It appears from the observations and experiments of Galli-Valerio and Rochaz 

 de Jongh that frogs and toads will not capture mosquito larvae or pupae. No 

 observations appear to have been made with reference to frogs and toads as de- 

 stroyers of adult mosquitoes but there can be no doubt that they capture mos- 

 quitoes along with other insects. The above-mentioned observers found that the 

 north African Discoglossus pictus, a frog-like batrachian, is an efficient de- 

 stroyer of mosquito larvae. This animal has the habit of capturing its prey under 

 water while the frogs and toads do not do so. The same observers found that in 

 Switzerland Triton cristatus and Triton alpestris are effective destroyers of 

 mosquito larvae. They observed that a certain puddle which in past years was 

 inhabited by Triton cristatus at that time contained no mosquito larvae ; during 

 two subsequent years, when the tritons were absent, this same puddle harbored 

 great numbers of mosquito larvae. They found that the larva of this triton, as 

 well as the adult, destroyed mosquito larvae. 



In the section on " Eemedies " under the head of the " Practical use of natural 

 enemies of mosquitoes," mention is made of the importation into Hawaii of the 

 western salamander or newt {Diemyctylus tortosus) which has been kept for 

 several weeks in an open tank by Mr. Albert Koebele, with the result that they 

 devoured all of the mosquito larvae in the tank. 



The aquatic larvte of our terrestrial salamanders are predaceous and feed on 

 mosquito larvae as well as other aquatic insects. Mr. W. L. McAtee of the Bio- 

 logical Survey has fed the larvae of Amhly stoma opacuni with larvae of Chaoborus 



