1916] Attraction of Diptera to Ammonia 413 



The odor of two cubic centimeters of the acid diluted with 

 fifty cubic centimeters of water was easily perceptible to a man 

 at a distance of fifteen feet from the dish. 



While my results do not agree with Howlett's, this may be 

 due to the fact that we used different methods, or even to some 

 dissimilarity in the responses of Stomoxys in the two regions. 

 One can conceive of the same species of insect attuned to respond 

 to certain odors in one environment, responding to very differ- 

 ent odors in another. 



CONCLUSION. 



The odor of ammonia attracts a varied dipterous aggrega- 

 tion. The species which respond to it are known to spend at 

 least a part of their lives in some form of animal excrement. 

 Practically all animal excrement gives off ammonia during 

 some stage in its decomposition. These flies are probably 

 lured to the manure chiefly by the odor of this gas. The 

 response is not always a simple one, but is sometimes com- 

 plicated by other factors, as has been shown in the studies on 

 Musca domestica L. referred to above. 



I am indebted to Mr. J. R. Malloch for the identification 

 of several species of Diptera. 



BIBLIOGRAPHY. 



Barrows, William Morton— 1907. The reactions of the pomace fly, Drosophila 



ampelophila Loew, to odorous substances. Journ. Exp. ZooL, vol. 4, pp. 



515-537, (5 figs.) 

 Chatterjee, N. C. — 1915. Chemotropism; influence of kusum oil on insects. Journ. 



Bombay Nat. Hist. Soc, Bombay, vol. 24, no. 1, pp. 198-199. 

 Hewlett, F. M. — 1912. The effect of oil of citronella on two species of Dacus. 



Trans. Ent. Soc. London, pp. 412-418, (pis. 39 and 40). 



1914. A trap for thrips. Journ Econ. Biol. London, vol. 9, no. 1, pp. 21-23. 

 Imms, A. D. — 1914. The scope and aims of applied entomology. Parasitology, 



vol. 7, no. 1, pp. 69-87. 

 Richardson, C. H. — 1916a. A chemotropic response of the house-fly, (Musca 



domestica L.). Science n. s., vol. 43, no. 1113, pp. 613-616. 



1916b. The Response of the House-Fly (Musca domestica L.) to Ammonia 



and Other Substances. Bull. 292, N. J. Agric. Expt. Station, 19 pp. 

 Severin, Henry H. P. and Severin, Harry C. — 1914a. Relative attractiveness of 



vegetable, animal and petroleum oils for the Mediterranean fruit fly (Ceratitis 



capitata Wied.) Journ. N. Y. Ent. Soc, vol. 22, no. 3, pp. 240-248. 



1914b. Behavior of the Mediterranean fruit fly (Ceratitis capitata Wied.) 



towards kerosene. Journ. Animal Behavior, vol. 4, no. 3. pp. 223-227. 

 Tragardh, I. — 1913. On the chemotropism of insects and its significance for 



economic entomology. Bull Ent. Research, vol. 4, pp. 113-117. 

 Verschaffffelt, E. — 1910. The cause determining the selection of food in some 



herbivorous insects. Proc. Sci. k. Akad. Wet., vol. 13, pp. 536-542. 



