80 



Life TTistory of "Paxtat.a flavescf.xs" Fabr. 



As far as eoiild be learned the life history of none of the loeal 

 dragonflies had been worked ont. As the draii'onfly 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 

 lirief review of the resnlts of some rearing experiments with the 

 Pantald will therefore be given. There are three distinct stages 

 in the life of the dragonfly, — the e^^\ the nymph, or growing- 

 period ; and the adidt, or matnre stage. 



Eci<i. — The eggs are whitish (later on they become ipiite 

 ^•ellow ) , snbspherical bodies, abont 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 ti]) of 

 her abdomen down on the snrface. The eggs of this species are 

 laid anywhere in the open where water flows or accnmnlates — 

 from a small mnd-pnddle in the street to a large stream or pond. 



The eggs for the pnrpose of carrying ont the breeding exper- 

 iments were secnred by catching female dragonflies in the act of 

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

 trnded from the bnrsa copnlatrix in large masses. The nnnd)er 

 of eggs thns obtained varied from 60 to several Inmdred. In 

 one case S16 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 1 days. 



Njiinpli. — The newly hatched nymph is abont two-tliird mm. 

 hmg. Its first activity is to monlt almost innnediately after 

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

 it is ready to start ont on its life-long hnnt for food, — food which 

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

 soon fonnd that, on acconnt of their strong cannibalistic char- 

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

 illnstration of their cannibalism the following incident may l)e 

 given: Seventy (69 Paniala and one Auax) nymj^hs of varions 

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

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

 were left 7 Paniala, the one Anax, and the little fish, so that 

 (>2 nym])hs were eaten by their fellows. 



Fonr nymphs were snccessfnlly reared to nuitnrity. The 

 following gives in tabnlar form the life history of the fonr 

 dragonflies from eg,Q^ to adnlt : 



