2 Dragon-Flies : their Life-History. [Sess. 



now known that the metamorphoses which those belonging to 

 the different orders undergo vary in degree and differ widely one 

 from another. Like all those with incomplete metamorphoses 

 (i.e., in which the changes are not sharply defined), dragon-flies 

 have no quiescent pupal condition, no abrupt transition be- 

 tween the larval and the " nymph " or pupa stage ; what 

 changes there are consist principally in increase in size. The 

 eggs are deposited in water, and when hatched give rise to 

 the larvae. These and their further advanced form or pupa? 

 are entirely aquatic, living at the bottoms of ponds, chiefly in 

 the mud or on the submerged parts of water-plants. 



The larval or first stage of life, properly so called, is one of 

 sterility, in which existence is usually more prolonged than in 

 any other. In it the active larva — one of the most predaceous 

 of insects — does nothing, from the moment it emerges from the 

 egg to the time when it quits the water to be transformed into, 

 or rather emerge as, the perfect form, but eat voraciously to 

 satisfy its insatiable hunger, — the result being rapid increase 

 of growth. This enlargement renders the casting of the skin,, 

 or moulting by means of a split in the back, a necessary pro- 

 cess. The number of moults is uncertain, but doubtless they 

 are numerous ; and on dissecting the larva, one is almost sure 

 to find the skin for the succeeding period of growth. At 

 probably about the penultimate of these operations rudiment- 

 ary wings begin to appear as thoracic offshoots, in the full- 

 grown nymph form extending about half-way along the back ; 

 and as ability to eat continues as before, they form the only 

 real difference between the two stages, or rather an indi- 

 cation of the latter of the two. The following instance, in 

 illustration of the nature of the insect in this stage, was 

 brought under my notice during this last summer. A gentle- 

 man, walking along the canal bank one evening, observed a 

 perch of medium size swimming rapidly in circles, diving 

 suddenly, and performing strange evolutions. He hooked it 

 out with the handle of his walking-stick, and found a larva 

 of dragon-fly holding on to the under side of the perch, and 

 the fish had been struggling to get rid of its tormentor. I 

 tested their devouring capabilities by placing three of these 

 large larvae in a vessel along with a quantity of frog-spawn 

 and a few larval forms of other insects. The latter they 



