RESEARCH IN BRITISH WEST AFRICA. 237 



bag of the net should be seized near the bottom so as to imprison ihe flies in a 

 small space ; this portion can then be placed bodily into the killing-bottle for a 

 minute or so, and when tlie insects cease to move they can all be transferred to 

 the bottle. 



The flies which are most urgently required are those which suck the blood of men 

 and animals, and of these long series should be sent from every different locality 

 visited. Tahuiiidae, Slomoxys, and tsetse-flies (Glossina) may often be captured 

 while attacking man and other mammals ; and it should be remembered that 

 freshly-killed animals are often as attractive, if not more so, than living ones. 



Ki LINING. — Flies brought: b.om.e alive, may be killed by the method recom- 

 mended for mosquitos. 



Preserving. — For general purposes these insects should be preserved chy, 

 either pinned or in papers. 



Pinned Specimens. — For insects not larger than a blue-bottle a No. 10 pin 

 should be used, and they should be treated in exactly the same manner as mos- 

 quitos. In the case of larger flies, they may be pinned with the long No. 16 

 pins. The insect should be pushed up the pin for at least two-thirds of its 

 length, and a card, on which all the data have been written, should be run up the 

 pin close beneath the insect, so as to serve as a support for its legs. 



Unpinned Specimens.— Vve^i^Ye a number of rectangular pieces of fairly thin 

 soft paper ; 2 x 2^, inches will be the most generally useful size, but 2^ x 3 inches 

 would be needed for the largest Diptera. Take one of these papers and write 

 on it all the particulars of capture, including the locality, date, name of collector, 

 &c. Make this into a " cushion " envelope as described and figured on page 229, 

 and pack only one insect in each. Never use yum to fasten the edge of the envelopes. 



Packing. — Pinned Insects. — These should be treated in precisely the same 

 manner as mosquitos. In the case of lai'ge insects, special care must be taken 

 that the pins are firmly driven into the bottom of the box as far as they will go. 

 In doing this never hold the pin above the insfect, but always below it. 



Insects in Papers. — For packing these, take a small tin or wooden box, pour a 

 few drops of medical creosote and also a spoonful of melted naphthaline into it to 

 prevent mould. Cover the bottom with a sheet of paper, then carefully put in 

 the envelopes in such a way as to minimise the pressure on the insects, and 

 replace the lid as soon as possible to prevent the evaporation of the creosote. 

 When the box is full, place a layer of teased-6iVt cotton-wool on the top of the 

 envelopes, using just sufficient to prevent them from moving about without unduly 

 pressing the specimens. Carefully pack the box in a covering box, and dispatch 

 it as soon after it is filled as possible. If the specimens have been kept for six 

 weeks or so before posting, put a/ew more drops of creosote on the cotton-wool 

 covering the envelopes. On no account must an excess of creosote be used or it 

 will discolour the insects. If medical creosote or other preventive of mould 

 is not procurable, the insects must be kept in wooden boxes only and as free 

 from damp as possible. In very moist climates it may be found necessary to 

 expose such specimens near a fire from time to time, or to place them in the sun, 

 care being taken not to allow ants or other destructive insects to gain access to 

 thera. 



21H67 D 2 



