MAY-FLY FISHING. 357 
flutters before the wind in a heavy laboured flight to the shore, 
unless in the meantime it has fallen a prey to one of its many 
enemies among the fish or the birds. 
The above is the natural order of the metamorphosis under 
normal circumstances, but very frequently the exact sequence 
is destroyed by some slight accident or mishap. Thus, as an 
example, some nymphs will reach the surface too soon, and 
float many yards down before the splitting open of the larval 
envelope can be accomplished ; others, again, will have par- 
tially or even entirely emerged from the shuck before reaching 
the top of the water, and may possibly be drowned or fatally 
crippled in the wings. Again, in many ways the order in 
which the various organs will become detached from the 
exuvium can be altered: the wings may 
be drawn out of the covers before the 
abdomen and sete leave the larval skin, 
or possibly one or more legs on one side 
may get entangled, to extricate which a very 
decided effort may be required. 
Such organs as are only of use in the 
mud or the water are shed with the 
exuvium ; among these may be noted 
the mandibles, the powerful digging claws, 
and the branchiz, whose function it is to separate from the 
water the air required by the nymph for respiratory purposes. 
The hairs which fringe the antenne, legs, body, and sete of 
the nymph are absent from the winged insect, the antenne 
are much shortened, and the mouth organs are generally atro- 
phied. The sete of the subimago are somewhat longer than 
those of the nymph. 
The subimago having flown ashore, finds shelter from the 
sun on blades of grass, sedges, or among the leaves of trees, 
and after a period of from twenty-four to thirty-six hours—the 
length of time being greater or less according to the tempera- 
ture—the final change to the imago or perfect insect takes place. 
As a preparatory step, the subimago fixes its claws firmly to 
SUBIMAGO. 
