DRAGONFLIES AND DAMSELFLIES IN PONDFISH CULTURE. 193 
Imaco.—In these latitudes the winter is passed in the nymph stage, and toward 
the close of the following spring the nymph, having passed through successive molts, 
is ready for transformation. This is accomplished by crawling out of the water on'to 
some convenient object near at hand, to which it fastens with its claws. In a short 
time the skin splits across the top of the head and then along the back and the imago 
or perfect insect emerges, leaving the old nymph skin, called an exuvia, fastened to its 
support. 
TENERAL.—After emerging, the imago is of a uniform pale yellow or tinged with 
blue, brown, or white, and it takes from a few hours to several days for it to acquire the 
bright colors of the mature adult. During this time it is called a teneral, its body is soft 
and flabby, its wings shine as if varnished, and its powers of flight are quite limited. 
= 
Fics. 1 to 3.—The egg of Pachydiplax longipennis: 1, newly laid; 2, three days old, dorsal view; 3, three days old, side view, 
showing at the right the large ventral plate and in the center the folded legs. Fic. 4.—Pronymph of Pachydiplar 
longipennis; length, o.90mm. Fic. s—Nymph of Pachydiplax longipennis after the first moult: length, x mm. 
PRUINOSE.—After becoming thoroughly hardened, some species, especially the 
males, are gradually covered with a bluish or whitish powder which may hide entirely 
the original bright colors; they are then said to be pruinose. 
In Plathemis lydia the old males are almost white on the dorsal surface; in Erythemis 
and Pachydiplax they become blue; while in the damselfly, Argia putrida, the thorax 
and the last two segments of the abdomen appear to be blue, but this color disappears 
at once when they are put in alcohol. 
MOUTH PARTS OF ODONATE NYMPHS, 
DRAGONFLY NympHs.—In dealing with the food of nymphs and adults we need to 
know a little about the means which they possess for seizing, eating, and digesting their 
prey; let us begin with the mouth parts. 
