1891-92-] Dragon- Flies : their Life- History. 3 



quickly demolished, and the spawn, when hatched into tad- 

 poles, disappeared steadily night after night, the remainder, 

 numbering about fifteen, being cleared out in a single night, 

 and this when they were between half an inch and three- 

 quarters of an inch in length. 



The duration of the aquatic life is no doubt variable accord- 

 ing to the species. In the smaller forms it is probably less 

 than a year, but definite evidence is wanting as to the occur- 

 rence of two broods in one year. On the other hand, as I 

 have taken larvae in full vigour from the bottom of a pool at 

 the end of September, it is certain that often a longer period 

 is requisite to enable the creature to attain its full growth, and 

 three years have been stated to be necessary for this in the 

 large and powerful Anax formosus. 



As is seen from the three specimens shown, representing 

 the three tribes into which dragon-flies are now divided, there 

 are two principal types of larva. One is broad, thick-set, and 

 clumsy, producing the larger and stouter dragon-flies ; the 

 other slender, and carrying leaf-like appendages at the tail. 

 These latter are the immature condition of the slender and 

 graceful members of the group. In the former we see a very 

 clingy, unprepossessing, and ugly creature, of a dirty-green 

 colour, with six sprawling legs, a broad flattened head, promi- 

 nent eyes, and two very short antennae. The thorax has 

 rough ridges on its upper surface ; the abdomen, broadest a 

 little behind the middle, has at its extremity some stout spine- 

 like processes surrounding the terminal orifice of the digestive 

 tube. In the second type the body is elongated, and tapers to 

 the extremity of the abdomen. It is also capable of vigorous 

 movement from side to side. The eyes are if anything more 

 prominent, giving the insect a hammer-headed appearance. 

 These larvae possess a gizzard — absent in the perfect insect 

 — to assist in triturating the hard parts of their food. In the 

 first type it has four protuberances, each furnished with five 

 or six teeth ; in the second type — the larva of the Agrionidaa 

 — the gizzard has ten divisions, each of which is furnished 

 with many minute teeth in the centre, and above these a 

 second row with fewer teeth. The |-inch objective is required 

 to make them out well. 



One of the remarkable peculiarities of the larvae of dragon- 



