COLLECTING AND REARING 
N COLLECTING dragonfly nymphs the best single 
j tool is a sieve-net which scrapes up the bottom 
sediment and sifts it at a single operation. Thus 
it gathers bottom sprawlers and _ burrowers. 
Being stoutly built it may be used, also, to 
sweep standing vegetation, to dislodge and 
gather up the climbing forms. A good sieve-net costs several dollars. 
Lacking a sieve-net, a common garden rake may be used. When 
there is a sloping shore, and the bottom is strewn with fallen trash 
(as is usually the case), the rake will draw ashore the mixed mud and 
trash and nymphs. When drawn out of the water the nymphs begin 
kicking and squirming, and may readily be found by picking over the 
rakings. 


Fig. 20. The reshaping of the end of the abdomen during the process of 
transformation in Ophiogomphus carolus. M, nymph; N and O, adult just 
emerged; P and Q, mature adult. 
The nymphs move shoreward and climb higher as the time of their 
transformation approaches; and forms that ordinarily live as sprawlers 
on the bottom, may at such times be found abundantly in mats of 
floating pond scum. A dip net of some sort will then be useful. A stout 
dip net is best for collecting from green, growing aquatic plants. 
For rearing the nymphs the best kind of a cage is the ‘“‘pillow cage’”’ 
(so called, from its shape) shown in figure 21. It is also the simplest. 
We have used very many kinds of rearing cages, and have discarded 
all the others for this one. It is made out of a square of ordinary 
window-screen wire-cloth. The tools needed are a tinner’s shears 
40 
