120 THE GOLDFISH AND ITS CULTURE. 
They all fiy very rapidly, feed upon insects of every description 
that they catch flying about, and from this fact they may’be made 
useful to destroy the mosquitoes in bedrooms and elsewhere. Al- 
though very voracious, they are perfectly harmless to man—they 
can not injure him in any way. The manner of their copulation is 
somewhat curious. The male fastens the extreme back part of its 
body to the neck of the female, and thus attached, both fly about for 
one or two hours, when, over some water, they separate. The 
female then deposits her small white eggs by immersing the posterior 
part of the body in the water, attaching them to the submerged 
surfaces of water-plants; there they remain until hatched. 
The larve or grubs of the dragon-flies live in the water; those 
of the libellula are short and thick, while those of the other genera 
are more slender, corresponding with the shape of the adult. The 
color of these grubs varies from blackish-brown to a brilliant green. 
They breathe through the posterior part of the body, which apparatus 
is also used to propel them forwards through the water, making them 
good swimmers. 
They are extremely destructive to young fish and fish-eggs, upon 
which, together with tadpoles and snails, they manage to make a 
good living. Instead of hunting their victims, they lay concealed in 
the mud with the eyes only protruding from the surface. Whenever 
a victim comes within reach, they produce their concealed pincers 
by a rapid motion, rarely missing the mark they aim at. (See 
illustration. ) 
There are instances on record where one of the larve of the 
libellula, which was overlooked in the fish-tank, destroyed two 
thousand (2,000) young fish in a week’s time. 
After they have attained their full growth, the grubs leave the 
water, climb upon some object projecting from it, when the perfect 
