Dr. G. B. Longstaff's Bionomic Notes on Butterfiies. 635 



Mortehoe, 25 August, 1908. The Syrphid fly, Chilosia 

 illustrata, Harr., is common, sometimes abundant, at 

 Mortehoe on the flowers of Ragwort, Hcradeuvi, 

 Anf/elica, etc., where it mimics Bomhus sylvarum, Linn., 

 and the more local Anthophora furcata, Panz., suffi- 

 ciently closely to have deceived for the moment such 

 an experienced hymenopterist as Dr. H. Swale. 



Of course we can form but a very imperfect idea of the 

 sense impressions of the lower animals. We know by 

 their actions that hawks see their prey from a consider- 

 able distance. The phenomena of mimicry compel the 

 inference that insectivorous birds, and possibly lizards, 

 appreciate comparatively minute differences of shape and 

 colour, yet it is quite conceivable that they cannot dis- 

 tinguish these at a greater distance than a myopic man. 

 We know even less about the sense impressions of insects, 

 in spite of the patient observations of Forel and Lubbock, 

 and the brilliant experiment of Exner. The whole subject 

 is discussed in detail by Dr. Auguste Forel, who seems to 

 have established the fact that insects have a very keen 

 perception of movement — possibly far more acute than 

 their sense of form and colour.* It has often occurred to 

 me when collecting butterflies that it is just possible that 

 they can smell a collector as far as they can see him. 



§ 7. Notes on the fiight of sundry Butterfiies. 



Too many systematic works deal with insects as mere 

 cabinet specimens, though there are notable exceptions. 

 Not the least valuable part of the late Mr. C. G. Barrett's 

 great work on the " Lepidoptera of the British Islands " is 

 his vivid description of their habits and flight. Again in 

 Moore's " Lepidoptera of Ceylon " the short notes on the 

 mode of flight of many species supplied by Capt. H. Wade- 

 Dalton, Mr. F. M. Mackwood and more frequently Capt. F. S. 

 Hutchison are of great interest. The value of the notes 

 in the last-named work is not diminished by the fact that 

 the observers are not always agreed. The habits of the 

 sexes are usually different ; the time of day, not to speak 

 of the weather, greatly affects their flight ; probably the 

 time that has elapsed since emergence from the pupa is 



* Forel, " The Senses of Insects." Translated by Macleod Yearsley, 

 1908, passim. 



