No. 401.] THE FRUITING OF THE BLUE FLAG. 377 
within its burrow and remains there as an imago, until the 
bursting of the capsules in autumn causes the seeds and the 
weevils to be shed together. 
To determine the extent of the damage done by the weevil 
to the flag seeds, I picked at random, in several situations, fifty 
well-developed capsules and counted the weevils inthem. The 
result by capsules was as follows: 
Number of larvz per capsule, o, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 15, 16. 
Number of times occurring, 3, 2, 4, 8, 4, 11, 3, 6 1, I, 2, I, I, I 
Thus, but three were found without larvae in them; two con- 
tained such numbers (fifteen and sixteen, respectively) that 
there were hardly enough seeds to insure their development ; 
the total number of larvae was 269, the average number per 
capsule, five. Each larva destroys on an average about four 
seeds; a preceding table has shown that the average number 
of seeds developing per capsule (among thirty counted) was 
forty-three. So it appeared that the weevils destroyed nearly 
half the seeds in capsules which had escaped other destroyers, 
all of which had had their turn first. 
While this weevil is the most constant enemy of the blue 
flag, it is at the same time the one best regulated. Unlike 
other enemies, it is present on or in the plant throughout the 
season, and, though occurring everywhere, it is never wholly 
destructive anywhere. Its own habits furnish checks to too 
great multiplication. This is but saying that the weevil repre- 
sents a higher type of ecologic specialization. It has become 
adapted for living on the blue flag exclusively. Other enemies 
might totally devastate the flag clumps and, in the next gener- 
ation, turn to some other food plant; but excessive injury by 
the weevil means future starvation for its kind. The grasshop- 
pers, Mamestra and Chzetopsis, work a havoc that strikingly 
suggests a disturbance of the balance of nature. But the wee- 
vil goes its accustomed way — the way into which it has been 
led by natural selection — and gets its living unobtrusively ; 
and save for the rather rare damage to flowers, which may as 
often be done after fertilization as before, the flags show no 
visible sign of the burden which, under natural conditions, 
they are doubtless able to carry. 
