80 HOW TO COLLECT DIPTERA (tWO-WINGED ELIES). 



to which a larva belongs. Larvae for preservation should be killed by 

 immersion for a 'tnomeiit 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 larvse 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 

 general, so that notes on the habits, distribution, seasonal occurrence, 

 relative frequency, etc., of particular species will always be of great 

 value and interest.* Particular attention should be paid to the 

 habits of hlood-suching species and others of economic importance. 

 A good look-out should also be kept for cases of mimicry between 

 Diptera and Hymenoptera, which will be found to occur chiefly 

 among the Syvphidce (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. Vohtcella, Arctophila, Galliprobola — the 

 resemblance is especially pronounced). Instances of mimicry between 

 Diptera and insects belonging to any Order other than Hymenoptera 

 are exceedingly rare. Cases of mimicry between partlcidar species 

 should be specially noted. 



* For special points in connection with Mosquitoes as to which information 

 is desired, see p. 88. 



