80 



Lirr-: TIistoky of "Paxtai.a flavescens" Fabr. 



As far as eonld be learned the life liistorv of none of the loeal 

 dragonflies had been worked ont. As the dragonfly is in evi- 

 dence all the year ronnd in Hawaii, it will be of interest to have 

 some idea as to the length of development from egg to adnlt. A 

 brief review of the resnlts of some rearing experiments with the 

 Pnufala will therefore be given. There are three distinct stages 

 in the life of the dragonfly, — the egg; the nymph, or growing 

 period : and the adnlt, or matnre stage. 



Eqq. — The eggs are whitish (later on they become qnite 

 yellow), snbspherical bodies, about one-fifth mm. by one-third 

 mm. in size. They are laid singly or a few at a time by the fe- 

 male as she flies close over a body of water striking the tip of 

 li.er abdomen down on the surface. The eggs of this species are 

 laid anywhere in the o]^en where water flows or accumulates — 

 from a small mud-puddle in the street to a large stream or pond. 



The eggs for the purpose of carrying out the breeding exper- 

 iments were secured by catching female dragonflies in the act of 

 ovipositing, and collecting in a glass those eggs which were ex- 

 truded from the bursa copulatrix in large masses. The numl)er 

 of eggs thus obtained varied from 50 to several hmidred. In 

 one case 816 were collected in this way from a single female, 

 most of which proved to be fertile. Each batch was placed sep- 

 arately in a small Petri dish filled with water where the eggs 

 hatched in from 5 to 7 days. 



Nymph. — The newly hatched nymph is al)out two-third mm. 

 long. Its first activity is to moult almost immediately after 

 hatching, increasing its length by a fraction of a millimeter, when 

 it is ready to start out on its life-long hunt for food, — food which 

 is in all cases animal life. In these rearing experiments it was 

 soon found that, on accoimt of their strong cannibalistic char- 

 acter, the nymphs had to be ]daced in separate vessels. As an 

 illustration of their cannibalism the following incident may be 

 given: Seventy (69 Pantala and one Anax) nymphs of various 

 sizes Avere placed in a small rearing tank and provided with no 

 outside food, except a small top minnow. One week later there 

 were left 7 Paidala. the one Anax\ and the little fish, so that 

 ('>2 nymphs were eaten by their fellows. 



Four nym])hs were successfully reared to maturity. The 

 following gives in tabular form the life history of the four 

 draii'onfiics from egg; to adnlt: 



