A. D. Im3is and M. a. Husain 287 



Traces of valerianic acid in ethyl alcohol is also an attractive mixture. 

 The experiments were as follows : 



1. Aug. 15-16. 10 °o ethyl alcoliol + traces of butyric acid 39 Diptera 



16-19. Water + „ ,, 3 



21-22. 10% ethyl alcohol +-5 c.c. butyric acid 82 



„ Water + -5 c.c. „ 2 



3. „ 22-24. 10% ethyl alcohol +-5 c.c. „ 20 



4- .. „ 10% ,, +-5 c.c. iso-butyric acid , 7 



>» A" /o >> — — — 2 



15-16. 10% „ + traces of valerianic acid 37 



The species attracted were as follows : an * indicates that the sex was 

 undetermined. 



4* 64* 19* Unidentified, mostly Anthomyidae 



39 82 37 Totals 



(11) Beer. Beer has long been known to exercise marked chemo- 

 tropic properties. It forms an important constituent of a number of 

 baits used on a practical scale, for the purpose of attracting and trapping 

 injurious Lepidoptera. Our observations confirm the high attractive 

 properties of this substance, and we have also been able to definitely 

 prove that it is equally, or even more, attractive in so far as Diptera 

 are concerned. Beer is a complex chemical substance, whose composition 

 varies in almost every sample, and it is essential to ascertain which 

 constituent or constituents exercises this power. Our researches are 

 now being conducted with this object in view. 



The following experiments were performed for the purpose of testing 

 the relative value of 50 per cent, solutions of beer and a mixture of beer 



