Prefatory Note.

Having had the privilege of seeing something of Mr. Chorley's very fine work against Glossina palpalis, and having had four of his traps (of the types shown in Pl. xi, figs. 1, 2, 5) in experimental use myself, I would like to state that he has, in my opinion, done particularly excellent service in evolving several good types of trap for this tsetse-fly. They have not been properly tested yet against other species of tsetse. The choice of exactly suitable sites for the traps, as with all tsetse-traps, is a matter of considerable difficulty and demands expert knowledge, but if skilfully sited, the traps catch well. They represent the acme of cheapness. The mere tacking of a skirt on a Conical Hoop Trap (1912), a Hughen's trap (1919) or a Barrel Trap (Burnett 1918) makes a “ Chorley ” Trap for tsetse-fly. A mere sack or trouserleg kept open by a hoop and with a non-return cage on the top suffices ; and the trap collapses, like a lady's dress, into no space at all. It is simply, in some of its forms (as in Pl. xi, figs. 1, 2, 5), a very slight adaptation to tsetse of Richmond's Crinoline Trap for mosquitos, published in 1927 in the Government of India's Health Bulletin, No. 11 ; in its “ ventilator ” forms (e.g., fig. 3), it is an adaptation of the Wahl & du Plessis trap for blow-flies, published in 1923 in the Journal of the Department of Agriculture of South Africa—though even here the form most used has been cylindrical.