242 
NATURE’S CRAFTSMEN 
came in. “But they are not so plump; their 
habit of burrowing under the sediment along the 
bottom tends to flatten them out. Indeed often 
all that can be seen of this species is the tip end of 
their body reaching upward for breathing pur¬ 
poses. Yet other nymphs exist that are so widely 
different in form that their relationship would 
never be suspected but for their bulldog faces. 
These nymphs have worm-shaped bodies, with 
three flat gauzy gills shaped like so many elm 
leaves clustered at the posterior end. 
“ Nymphs are the larvae of certain very inter¬ 
esting little winged creatures, but I am not going 
to disclose their identity. Feed your captives 
well on flies or any other creatures that come to 
hand which are smaller or weaker than them¬ 
selves, and watch daily for developments. You 
will find them changing their suits whenever they 
get too small, and probably several such changes 
will be made before the grand transformation. 
The nymph does not pupate; when it gets good 
and ready it simply casts its old larval skin and 
unfolds its wings, shakes them dry and sets out 
on its self-appointed task of policing the air for 
flies, gnats and mosquitoes.” 
“Air policemen are they —hmm ” murmured 
Max. “ Let’s see: if we guess ’em, will you tell 
us, Uncle John? ” 
“No, he W 071 H” Tommy decided sharply. 
