80 HOW TO COLLECT DIPTERA (TWO-WINGED PLIES). 
to which a larva belongs. Larvae for preservation should be killed by 
immersion for a moment or two in boiling water, and should then be 
placed in weak spirit (two-thirds spirit and one-third water); after 
being allowed to remain in this for two or three weeks until 
thoroughly hardened, they can be transferred to stronger spirit. 
The larvae of each species must of course be kept separate, and 
should be put up in a small corked glass-tube full of spirit, the 
necessary particulars, with, if possible, a reference to pinned specimens 
of the perfect insect, being written in pencil on a scrap of paper and 
placed inside. 
Notes on Habits, etc. 
Very little is yet known as to the bionomics of Diptera in 
geneial, so that notes on the habits, distribution, seasonal occurrence, 
lelative frequency, etc., of particular species will always be of great 
value and interest.* Particular attention should be paid to the 
habits of bloodsucking species and others of economic importance. 
A good look-out should also be kept for cases of mimicrj between 
Diptera and, Hymenoptera, which will be found to occur chiefly 
among, the Syrphidce (to a lesser degree also among the Asilidce. 
The Syrphidce as a family may be said to mimic Hymenoptera 
but in some genera—e.g. Volucella, Arctophila , Calliprobola—iYiQ 
resemblance is especially pronounced). Instances of mimicry between 
Diptera and insects belonging to any Order other than Hymenoptera 
a , re ex f edin gly rare - Cases of mimicry between particular species 
should be specially noted. 
. *, b. or special points in connection with Mosquitoes as to which information 
is desired, see p. 88. „ 
