420 THE INSECT WORLD. 
and begin to eat it. I have remarked that they do not spare those 
of their own kind, but that they eat each other up when they can, 
and I have also seen them devouring very small fish which I put 
by them. It is very difficult for other insects to avoid their blows, 
because, walking along generally in the water very gently, and, 
as it were, with measured steps, almost in the same way a cat does 
on the look-out for birds, they suddenly dart forward their mask 
and seize their prey instantaneously.”* Fig. 393 represents, to 
the left, the larva of the dragon-fly, with the instrument of attack 
which we have called “a mask,” and which it is making use of 






Fig. 393.—Larva of the Libed/u/a and the perfect insect emerging. 
for seizing a small insect; ou the right, the adult dragon-fly 
coming out of the nymph. 
The respiration of these larvee is very singular. Their abdomen 
is terminated by appendages which they open to allow the water to 
penetrate into the digestive tube, whose sides are furnished with 
gills communicating with the trachee. The water, deprived of 
oxygen, is then thrown out, and the larva advances thus in the 
water by the recoil. It has no tufts of external lateral gills, which 
* Charles de Geer, ‘‘ Mémoires pour servir 4 l Histoire des Insectes,” tome ii., 
2e partie, p. 674. 
