140 Notes on Chemotrqpism in the House-Fly 



Sarcophaga assidua Walk, was a common insect at the time, and 

 was attracted to valerianic acid, grape juice, and banana only. Howlett 

 has observed that other species of Sarcophaga are strongly influenced 

 by a solution of Skatol, which contains the benzene ring and a methyl 

 group. This substance is found in faeces. Its effect upon Sarcophaga 

 seems to be to guide the female to places for oviposition. It may be 

 that the benzene ring reacts positively to fertile females, and products 

 of fermentation to individuals generally as a guide to food only. 



Amongst the other insects caught in these experiments, the Cole- 

 optera, Epitrix parvula Fab., and Chaetocnema denticulata Illiger, oc- 

 curred in valerianic aldehyde and amyl acetate respectively — one 

 specimen of each. 



Gryllidae were often found in traps baited with essential oils, namely, 

 citronella, lemon, and camphor oil: also in traps baited with amyl 

 alcohol and methyl alcohol, but in the latter cases seldom more than 

 one in each trap. 



Thysaneura of the Genus Lepidocyrtus, and, on Mr Banks' authority, 

 closely allied to, but distinct from L. metallicus, were attracted in some 

 numbers to amyl acetate, valerianic acid, and amyl alcohol. These 

 insects were not influenced by benzaldehyde or cinnamic acid. 



Finally, it is not considered that the Valerianic series of substances 

 is necessarily the series acting most positively to the house-fly, and it 

 is suggested that experiments be carried out with the Butyric series. 



