A. D. Imms and M. a. Husain 283 



All the oils enumerated above wer6 used both in wire balloon traps 

 and the Minnesota model traps. In one series of experiments a few drops 

 were allowed to fall on blotting paper and placed in the usual receptacle 

 within the traps. In a second series of experiments, an approximately 

 similar quantity of each oil was added to 50 c.c. of water and shaken to 

 form an emulsion. 



(2) Kerosene. This substance is known abroad to attract insects 

 belonging to such diverse groups as aphids, mosquitos, barklice, moths, 

 cockroaches, Syrphid flies, Coccinellidae and their larvae, also a number 

 of Tachinidae and parasitic Hymenoptera (Severin, H..H. P. and H. C, 

 1915). In our experiments it was exposed on four occasions: during one 

 exposure it attracted a number of Nematocera, but on the remaining 

 occasions the results were negative. It is important, however, to recog- 

 nise that the kerosene used in these trials probably differed in composition 

 from that employed in America. 



(3) Vinegar. The records were as follows : 



Aug. 19-30. 40 c.c. vinegar 100 c.c. water 22 Diptera 



Aug. 30-31. 25 c.c. „ 50 c.c. „ 3 



10 c.c. „ 50 c.c. „ 1 „ and 1 Vespa vulgaris 



5 c.c. „ 50 c.c. „ 2 „ 



Aug. 31. 40 c.c. „ 100 c.c. „ 5 



(4) Ethyl alcohol. Ethyl alcohol (approximately 95 per cent, strength) 

 was used in the following percentages, 36, 22-5, 12-5, 10, 7, 5, 3, 2*5, 1, 

 •7, -4, and -2. These solutions (50 c.c.) were used both as controls for other 

 experiments and as independent chemotropic agents, but no attractive 

 properties were evident in any instance. Our experiments with solutions 

 stronger than 36 per cent, were vitiated, and need to be repeated. The 

 5 per cent, solution attracted eight Diptera and this result was only 

 achieved after 48 hours exposure. Our results are somewhat remarkable 

 in view of the fact that Richardson (1917), in New Jersey, caught 891 

 examples of Musca domestica in the course of six experiments, representing 

 an aggregate of 207 hours exposure, using 4 per cent, ethyl alcohol. 

 This observer found that a 10 per cent, solution, exposed in the same 

 series of experiments, attracted 544 examples of that same species, 

 which made up more than 95 per cent, of the Diptera attracted during 

 the whole course of his trials. The latter were conducted within 50 yards 

 of a prolific breeding ground of the insect, and our own experiments 

 were carried out within 60 yards of farm accumulations of manure, and 

 decaying organic matter of various kinds. Buck (1915), also in America, 

 observed that not less than 3 per cent, and not more than 8 per cent, of 

 95 per cent, ethyl alcohol was a markedly attractive agent. 



