BULLETIN 39, UNITED STATES NATIONAL MUSEUM. 



[6] 



The following adequate and very simple method is commended : Take 

 afield a pocket full of small paper bags, of the coarsest sort used by 

 grocers, and finding imagoes emerging, slip them singly into the bags, 

 each with its own cast skin, writing desired data on the outside of the 

 bag. Before the skin is lifted from Its support the claws should be loos- 

 ened carefully with forceps, else legs will be broken off. Yery delicate 

 and easily broken skins may be slipped into envelopes of tissue paper 

 before they are dropped into the bag; this will diminish the danger 

 of breaking from being tumbled about ; or, they may at once be put into 

 vials of alcohol and numbered to correspond with their imagoes. The 

 bags are closed by twisting the top. To the rough interior the imago 

 clings easily, with plenty of room for exj)anding and drying its wings. 

 Bags thus filled may be carried home loosely piled into a large basket 

 or in a large sack. They should be left unopened for a day" or two, 



until the mature coloration 

 of the imagoes has ap- 

 peared, and the form of all 

 parts is well fixed by chiti- 

 nization. With may flies, 

 specimens of the subimago 

 should of course be pre- 

 served on the approach of 

 the time for the final molt- 

 ing. 



While gathering such 

 material one should en- 

 deavor to get besides males 

 and females with their skins 

 (only afew of which for each 

 species need be kept sepa- 

 rately for x^ositive determi- 

 nation) also nymphs leaving or ready to leave the water and others 

 transforming; and, as in other collecting, good series are very desirable. 

 As to the time and place for such collecting little need be said, since 

 members of these three orders are transforming throughout the open 

 season and live in all sorts of fresh water. Certain stone flies may, 

 indeed, be found transforming abundantly in midwinter. In general, 

 it may be stated that the nymphs all transform at the edge of the 

 water. A few, like Gomphns villosipes, may clamber only far enough 

 upon sloping banks to expose their backs, while others, like some of 

 the larger Lihelhdidce, may crawl several rods from the water, when 

 this is necessary, to find suitable place to transform. The majority 

 transform within a few inches of the water's edge. Some specie of 

 these three orders transform habitually at night, many throughout the 

 day, but a majority of the dragon flies, at least, transform early in the 

 morning. 



Fig. 3. — A morning's catch of dragon flies taken in transfor- 

 mation and properly fixed for maturing ttieir colors. 



