58 THE SCOTTISH NATURALIST 



of Cordyluridae, Ephydridas, Limnobiidae, and DoHchopodidae, 

 while the foliage of the trees overhanging the margins of a 

 pond or stream often harbours a number of Empidae, 

 Simuliidre, and other groups. The hour of sunset is par 

 excellence the time for the appearance of the tiny but 

 interesting and beautiful midges of the family Chironomidae, 

 Large swarms, each as a rule made up of a single species, 

 may be commonly seen disporting over a damp spot on 

 the margin of a ditch or stream on a calm, clear afternoon 

 when the sun is disappearing, and in a few minutes more 

 specimens can be obtained than it is possible to pin and 

 preserve to say nothing of the task of identification. 

 Lastly, Dung-flies {Scatophaga, Borborus^ etc.), Carrion- and 

 Flesh-flies {SarcopJiaga and its relatives), and Fungus-gnats 

 (Mycetophilidae) are to be sought for in the habitats 

 suggested by their names, while obviously Gad-flies, Bot-flies 

 and other parasitic forms are seldom met with except in the 

 vicinity of their hosts. 



Apparatus Required. 



The outfit of a collector of Diptera is comparatively 

 simple and inexpensive. The first item to be considered is 

 the net. The material of which the bag is made should be 

 much softer and finer meshed than those usually employed 

 by the lepidopterist, should be either green or white, while in 

 shape it should taper backwards from its mouth almost to 

 a point. The writer uses a soft green silk gauze, but some 

 collectors prefer a white material for the sake of greater 

 facility in detecting the minuter specimens. The ring should 

 be of strong wire (about one-eighth of an inch in diameter) 

 and nickel-silver may be strongly recommended as not liable 

 to rust, while the ring should by means of loops or rivets be 

 divided into four segments so that when not in use it can, 

 without removing the bag, be folded up and carried in a bag 

 or even in the pocket. The stick to which it is screwed 

 should not be longer than 2 feet, and must be light but 

 strong, preferably of bamboo. A spare bag should invariably 

 accompany the collector, in case of accident to the first one. 

 The butterfly-nets (small model) supplied by De}'rolle & Co., 



