9 
Method of Colleoting’ and Killing-. 
For capturing mosquitoes in the open an entomologist’s 
collecting net is necessary, from which the insects can be 
transferred to glass-bottomed pill-boxes ; in doing this great 
care must be taken not to pull off the legs ; inside buildings 
it is possible, with care, to capture mosquitoes on walls and 
windows in the pill-boxes themselves. Specimens of species 
that habitually infest houses are best obtained in good con- 
dition by breeding them ; this can readily be done by 
keeping the larvae or pup<e in a basin of water covered over 
with book-muslin. In any case mosquitoes should be col- 
lected alive in the glass-bottomed pill -boxes*; if care is 
taken, several specimens can be got into one pill -box. To 
kill the mosquitoes the box is opened a fraction of an inch 
on one side, and placed for a few minutes in a cj-anide 
killing-jar, t which must, of course, be closed. As soon as 
the insects are quite dead (if the mixture in the jar is of 
* These boxes can be obtained from any dealer in natural history 
apparatus, but care should be taken to see that the hotfomis — and not the 
tops, as is often the case — are made of glass. Since the boxes are con- 
structed of cardboard, they are liable in tropical countries to go to pieces 
in the rains, and to prevent this they should be covered with jaconet 
(cut on Ihe cnm and stuck on with liquid glue) and then coat^ with 
Aspinall’s enamel. 
t A cyanide killing-bottle can be procured ready for use from Hinton 
and Co., Bedford Street, London, W.C., or any other chemist will prepare 
one to order, but when mosquitoes (or inde^ any Diptera) are collected 
in the manner here advised it is preferable to make a large-sized killing- 
jar for oneself as follows Take any fairly large glass jar (such as a 
pickle-bottle) with a wide mouth and closely fitting lid, and cover the 
bottom with a layer of dry plaster of Paris to the depth of half an inch ; 
pour in above this a layer equal in depth consisting of jwwd^’rrd cyanide of 
potassium, mixed A^ith rather more than its bulk of dry plaster of Paris ; 
cover this mixture with a layer of dry plaster of Paris to the depth of a 
quarter of an inch or so, and pour in above the whole a layer, half an inch 
in depth, consisting of plaster of Paris mixed with water to the con- 
sistency of cream. As soon as the top layer of plaster is dry the jar is 
ready for use. To obviate the risk of cracking the j.ar owing to the heat 
evolved when plaster of Paris is mixed Avith Avater, it may be advisable to 
stand the jar in Avarm Avater before adding the final layer. The exact 
amount of cyanide of potassium to be used is of no great consequence, but 
in the case of a properly prepared jar the odour should be readily per- 
ceptible on removing the lid ; if it is not, the reason may be that the 
mixture is too dry, Avhen a little Avater poured on to the top layer Avill 
probably set matters right. After some months’ use the cyanide loses its 
efficacy (to obviate this so far as possible the jar should never be alloAved 
to remain open), and the mixture must then be rencAved. 
