Des 
Prof. Riley, indeed, remarks in the first report: ‘‘There is every 
reason to believe, however, that Nature has her own means of keep- 
ing these flies within due bounds, for they are known to be preyed 
upon by parasitic Ichneumon flies in Hurope, and I noticed many 
flies of this last description, of polished hues and active movements, 
deftly darting through and resting upon the wheat plants of the 
fields infested with the Meromyza.”’ 
Mr. Lintner makes no mention of parasites in his article on this 
species, and the first discovery of them was made by myself in 
April of this year, among specimens from the field at Cuba already 
frequently referred to, which I was rearing to the perfect stage. 
Indeed, the first pupa-case of Meromyza which I opened (April 25), 
contained a well formed pupa of a hymenopterous parasite (Plate 
II, Fig. 2), and on the 6th of May—two days after the adult Mero- 
myzas began to appear,—two mature specimens of this parasite oc- 
curred in our breeding cages. These were evidently of the genus 
Ceelinius, but of a species of which I have not been able to find 
any description, and which is probably new. 
The abundance of these parasites in this field may be inferred 
from the fact that out of fifty-five larve obtained here, only twenty- 
one developed the fly, and the thirty-four remaining all gave origin 
to the Ccelinius, which continued to emerge from May 6 to May 
19. Sweepings of these infested fields in April yielded none of this 
species, and there can be no doubt that the eggs are deposited 
within the bodies of the larve in autumn. 
Whether this same parasite infests likewise the summer brood of 
larve, we are unable to say; but it seems extremely doubtful if it 
is at that time as destructive to the host species as when the latter 
is freely exposed to its attack among the leaves of the young wheat. 
It is' probably partly on this account that the midsummer brood 
seems much less numerous and destructive than the autumnal. The 
attack of the parasite does not arrest the growth of the larva, and 
consequently cannot prevent the injury to the plant; but, on the 
contrary, the infested worm goes on eating until it is ready to pu- 
pate, and, indeed, actually transforms. The prevalence of the para- 
site must, however, greatly diminish the number of the perfect 
insects appearing in spring, and consequently of the midsummer 
larve. On the other hand, the relative immunity of the latter from 
parasitism will not increase their own mischief in the field, but will 
_ have the effect to increase the number of the autumnal brood. 
In short, as the parasitism takes effect only on the damage done 
by the generation succeeding that parasitized, and as it seems to 
prevail chiefly among the winter brood of the larvie, it is the mid- 
summer brood whose injuries are lessened by it,—from which it fol- 
lows that the autumnal and winter brood will ordinarily be found 
the more mischievous of the two. There is, however, one circum- 
stance to modify this conclusion. The autumnal damage, and even 
that of spring, is done at a time when the wheat plant is some- 
times able, by tillermg, to replace in part the stalks killed by the 
worms, while that of midsummer is irremediable. I add description 
and figure of this parasite. 
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