10 NORTH AMERICAN DIPTERA 



For the encouragement he has given during the preparation of the 

 manuscript I shall always feel a deep sense of gratitude to Dr. Frank 

 E. Lutz. The American Museum of Natural History is deserving of 

 particular mention, since the work has been done in this institution 

 without any limitations as to time devoted to it. 



If the book should be found useful and helpful, full credit should be 

 given to the ]\Iuseum as well as to all those who have so generously 

 given of their time and knowledge. 



Collection and Care of Diptera 



So much has been written about the ease with which collections of 

 insects may be cared for that I feel a word of warning to be not amiss. 

 It is true the Lepidoptera and Odonata may be "papered", Hymenop- 

 tera, Hemiptera and CoIeoiJtera may be packed between layers of cotton 

 and Coleoptera may be collected in alcohol but most of the other Orders 

 require more care. With the exception of Coleoptera and the small 

 insects normally collected in alcohol and intended for study in this 

 liquid, or for slide preparation, all insects are much better pinned while 

 fresh. Packing Diptera between layers of cotton may result in recog- 

 nizable si^ecimens and a small percentage of really good specimens may 

 be secured but the majority can never be made to look attractive. 



With small flies pinning should take place within four or five hours 

 of the time of capture and all specimens should be mounted within eight 

 hours. In cold or damp weather a greater time may be allowed to elapse 

 and the time should be shortened in hot, dry weather. 



Mounting Diptera should not be a slip-shod process and care should 

 be taken to have the flies an even height on the pins. An excellent prac- 

 tice is to have the mesonotum about one-third the distance from the top 

 of the pin. This i)ermits of careful handling of the specimen and re- 

 duces danger of damage to a minimum. Many Entomologists pin Diptera 

 less than a fourth the distance from the head of the pin with the result 

 that the specimens are quickly damaged and ultimately cease to have 

 value. Double mounts should never be used for Diptera. If a specim'ni 

 is too small to be pinned through the thorax it should be fastened to 

 the side of the i)in by first circling it (the pin) with a narrow ring of 

 white shellac and touching it to the side of the insect. In this way the 

 specimen may be handled in the usual manner and all parts may be 

 readily seen. If possible, the wings should be arranged so that they 

 extend over the back of the insect in an upright position. Pins of suit- 



