1916] Attraction of Diptera to Ammonia 409 



reactions in Drosophila. The author ascertained also that 

 the olfactory organs in Drosophila which are concerned with the 

 location of food are situated in the third or terminal segments 

 of the antennas. When stimulated by a weak food odor the 

 flies responded by random movements, but as they passed into an 

 area of greater stimulation, they became directly oriented and 

 proceeded toward the source of the odor. 



Verschaffelt (1910) has pubHshed an important paper on the 

 compounds that determine the selection of food in larvae of 

 Pieris brassiccE and Pieris rapcB. These larv« feed upon certain 

 Cruciferae as well as Tropaeolium and Reseda, plants which 

 contain a group of glucosides, the mustard oils. A solution 

 of sinigrin, one of these mustard oils, when spread upon foUage 

 which the larvas ordinarily refused caused them to devour it 

 readily. The larvae of a sawfly, Priophorus padi, which feed 

 upon the leaves of certain Rosaceas, were attracted by amygda- 

 line, a glucoside found in these plants. 



Howlett (1912) attracted fruit-flies of the genus Dacus to 

 rags moistened with oil of citronella. Only the males responded 

 to this odor and he was able to show quite conclusively that the 

 females emit an odor closely resembling the oil of citronella. 

 In other experiments he induced a species of Sarcophaga to 

 deposit larv^ in a flask containing a solution of skatol, a com- 

 pound present in the feces of many animals. He also found that 

 Stomoxys calcitrans L. would oviposit on cotton-wool which 

 had been soaked in valerianic acid and that both valerianic 

 and butyric acids were similarly attractive to an ortaHd fly 

 of the genus Ulidia (?). The work was done at Pusa, India. 



The same author (Howlett, 1914) demonstrated the attract- 

 iveness of benzaldehyde, cinnamylaldehyde and anisaldehyde 

 to two undetermined species of thrips. SaHcylaldehyde and 

 isobutylaldehyde were also tried, but the results from these 

 were not so striking. The experiments were conducted in 

 England during the months of November and December, when 

 thrips are not abundant. The author believes larger catches 

 would be obtained in summer. 



The Severins (1914, a and b), have studied the attractiveness 

 of various oils to the Mediterranean Fruit-fly, Ceratitis capitata 

 Wied. in the Hawaiian Islands. Kerosene was used as a bait 

 in many experiments and it was found that most of the flies 

 captured were males. Indeed in eight month's trapping an 



