ence to the commonly cultivated wheats, and has 
been supposed or observed to do prime injury to 
some, secondary injury to others, and little in- 
jury or none to others. One reason why some 
wheats are little affected by it may be that they 
are generally sown at a time which, conjointly 
with their habits, occasions their coming into 
~ear ata period when the midge is not in a con- 
dition to attack them ; and another reason why 
the same or other varieties enjoy comparative 
safety may be that they have too hard an enve- 
lope to be readily pierced by the midge’s ovipo- 
sitor. “The species of woolly-eared, Lammas 
red, and Rivet wheats,” says Mr. Shirreff, “ have 
been stated in Hast Lothian to resist the attack 
of the fly. The two first mentioned kinds come 
into ear about a week sooner, the last about a week 
later, than those commonly cultivated, and to these 
peculiarities owe their occasional escape, earing 
either before or after the general depositing of 
eggs takes place. The fly, however, does not al- 
ways appear in strict conformity with the growth 
of the wheat plant, and the earing of different 
species is late or early, compared with the general 
crop, according to the time at which they are 
sown, ‘The eggs of the wheat-fly are generally 
deposited when the ear is escaping from the 
sheath,—and when delayed beyond this period, 
the grains either become diminutive, or the mag- 
gots perish; and therefore a species of wheat in 
some measure impervious to the ovipositor of the 
fly at this stage of the plant’s growth must tend 
to mitigate the ravages of the fly. There is such 
a species cultivated in many countries, the name 
of which is the Polish wheat, Triticum poloni- 
cum. It is characterized by a large exterior 
chaff, which closely envelopes the cups when the 
ear is escaping from the sheath, and at this time 
defends the flower in a great measure from the 
fily’s ovipositor. J have grown the polonicum, on 
a small scale, amongst other kinds; and although 
it did not altogether escape the attack of the 
fly, it was much less injured than any of those 
which came into ear at the same time.” The 
| Triticum polonieum, however, is very far from 
being eminent in other good agricultural proper- 
ties; and, if really proof against the midge, it} 
circumstances upon the fly. 
probably could not render better service to far- 
mers than by being made to communicate its 
large exterior chaff to some of the best cultivated 
varieties through the process of hybridizement. 
A variety called in some parts of England cone 
wheat, and known in some parts of Scotland as 
antifly or cone Rivet or German thickset wheat, 
belonging to the species Triticum turgidum, and 
somewhat nearly akin to the common Rivet and 
Pole Rivet wheats, possessing a tall vigorous 
stem, and yielding a very large produce, though 
the grains are coarse and of inferior quality to 
those of the common winter wheat, was found by | 
Mr. Gorrie, in the course of comparative experi- 
ments during the prevalence of the wheat-midge 
in 1829, to be completely proof against the midge. 
WHEAT-FLY. 
707 
“JT had a fall of it,” says he, “growing in the 
centre of a field of common wheat, which came 
in the ear on the 22d June, exactly at the same 
time with the common variety. At that period, 
I visited the field every evening for a week, and 
although the flies were numerously and busily 
employed on every ear of the common wheat, the 
half of which they destroyed, I, and my friends, 
who went frequently with me, could only detect 
one solitary fly at work on the new variety ; and 
although the ear was marked, no maggots could 
therein be afterwards observed.” The field of 15 
acres examined by Mr. Kirby was planted partly 
with common white wheat and partly with com- 
mon red; and the result of his examination was 
that in thirty ears of the white, seventy-three 
grains were destroyed by the fly, being at the 
rate of not quite 25 grains per ear, while in 
twenty ears of the red twenty-nine grains were 
destroyed, being at the rate of not quite 14 grain 
per ear. But all these instances, as well as 
some others which have been recorded, are pro- 
bably more or less deceptive; and the different 
results may have been in an appreciable measure 
due either to the accidental circumstance of one 
crop being more exactly in the stage of fitness for 
the insect’s use than another, or to the influence 
of the gregarious habits of the midge, whose 
swarms usually assemble and remain in the 
neighbourhood of the spot where it first finds a 
nidus or is induced to make a settlement; and 
even in periods and districts which have become 
signalized by great and recent ravages of the 
midge, many an intelligent farmer may perhaps 
think himself less safe in trusting to the reputed 
antifly properties of any particular variety, than 
in aiming to bring wheat crops of the best com- 
mon agricultural varieties into developement a 
little before or after the time when the fly is 
likely to be most active in the work of deposit- 
ing its eggs. Yet though this device might seem 
to be obvious and efficient, and though it has 
been recommended as a preventive by very dis- 
tinguished practical agriculturists, it may often 
be baffled either by the retarding or accelerating 
of unusual weather upon the crops, or by the 
sustaining and modifying influence of. unusual 
“The designs of 
Nature,” remarks Mr. Duncan, “are not to be 
thus easily frustrated. There is a plastic and ac- 
commodating principle in the nature of insects, 
conferred upon them by that Benevolence which 
-careth for all its creatures, apparently for the 
express purpose of enabling them to maintain their 
existence among the numerous hostile influences 
to which they are continually exposed. In such 
a case as that here supposed—the female being 
ready to deposit her eggs before the appropriate 
plant is ready to receive them—it usually hap- 
pens that the life of the insect is purposely pro- 
longed until a suitable opportunity occur for con- 
tinuing the species. A whole season is in this way 
sometimes added tothe ordinary duration of insect 
