DRAGONFLIES AND DAMSELFLIES IN PONDFISH CULTURE. 207 
The nymph eats voraciously as long as it remains light colored; while the color 
pattern is disappearing the amount eaten also diminishes, and after it has turned brown 
the nymph’s gizzard contains little if any food. All the nymphs whose gizzards were 
empty were dark-colored, but the intestine usually contained indigestible débris from food 
previously eaten. One very dark nymph of L. /uctuosa contained only a single tiny Cypris 
imequivala, another had but one Ceratopogon larva, while a third yielded two Ischnura 
nymphs with nothing in the intestine. Similarly two dark-colored nymphs of Anax had 
each eaten but one Ischnura nymph, and the intestines were empty. A dark nymph of 
E. simplicicollis contained only half a dozen short algal filaments with nothing in the 
intestine. This condition is particularly true of nymphs as they approach their final 
transformation, when they apparently fast for quite a long period before crawling out 
of the water. Hence we conclude that an empty digestive tube is one of the essential 
prerequisites for the great change which then takes place. 
Warren (1915, p.8) has given the lengths of the various instars, meaning by that the 
periods between molts, during the entire nymphal life of four specimens of Pantala fla- 
vescens. ‘These periods are about the same length for the first 9 or 10 molts and then 
increase greatly the last two molts. The final period, corresponding to the pupal stage in 
insects which have a complete metamorphosis, lasted for a month, while the first nine 
molts were only five or six dayseach. He did not record the periods of fasting, but it is 
probable that these nymphs ate very little during the last week before transformation. 
Balfour-Brown (1909, p. 270) similarly found that the periods between molts tend 
to lengthen as the nymph grows larger. In some of his damselflies there were nearly two 
months in the last period; in such cases the fast preceding transformation would also be 
lengthened. 
Besides these fasts which accompany the various molts and the one which precedes 
the final emergence, the nymph is able to go without food for long intervals when necessary 
and apparently suffer no injury. It is doubtful, however, if a nymph could transform 
when the fast preceding emergence was considerably lengthened. It is quite possible 
that some of the failures to fully emerge from the nymph skin (p. 222) may be caused by 
an insufficiency of food. 
Foop oF Hawalan Nympus.—Warren examined the contents of the alimentary 
canal of 253 Anax and Pantala nymphs captured in the vicinity of Honolulu, Hawaii, and 
it is interesting to compare his results with those recorded for Fairport. (See table, 
p. 201.) 
Foop Founp In ALIMENTARY CANAL OF 253 ODONATE NympHs FROM HONOLULU, Hawan, 
EXAMINED By A. WARREN. 
Molisea:, Spiral SHES so 60)0.<0:¢.c.0:020 oie, obo 14 | Ants and bees: 
CCEES DIV CISCIG EE 1, «ciao t ots sie.0. es vielleese Mh lot 16 Pheidole megacephala (Myrmicidez)..... 2 
Flies: Ants, undetermined species.............. II 
Ciitrononitd larvee es. see Shh eck ek 168 | Dragonflies: Pantala flavescens, nymphs..... 6 
Ciiroromid adultss . 62 ..)0402 40. ea 4 | Crustacea: 
Mosquito larve and pupe.............. 12 CY PHS) SPias pores =1.he Ae. OR 108 
WSO LO ACUTE 2s wie aap eo Se REL I DHEAINS SSP oc sxcieini-rietoia.cl Sasa 3 
DTT TSTMVELTEN Ecco ois src 6 ot, 5 spp does a «.6, «ice {| Protozoa: Euglena, sp...< 2... 2 qeeeer eee nee 30 
Adult fly, undetermined................ T jf Worms: (Nereis; Spo...)... 2.1. as oe a eS I 
Bugs: Ayphibians: Tadpoles ./2/). iy: aalestee’ «crane 8 
Merragata hebroides (Nzogeide)........ 1 | Fish: Top minnow (?)...................00 I 
bd 
Microvelia vagans (Veliide)............ 
