WHEAT-FLY. 
which has never obtained any distinctive popu- 
lar name. All these are dipterous insects or true 
flies; and the first and second belong to the 
tipula family, and the third to the musca family. 
The genus Cecidomyia is an extensive group, 
and comprises nearly 30 British species. Their 
antenne are slender, granose, as long as the head 
or longer, more or less necklace-shaped, com- 
prising in the female 13 subovate joints, and 
furnished with short verticillated hairs; their 
eyes are entire, and either oval or round; their 
forehead is narrowed and prolonged in the man- 
ner of a rostrum; their wings are membranous, 
ciliated, pubescent, and incumbent on the body, 
and present each but three nervures ; their pal- 
pi are long and four-jointed; and the extremity 
of their tibie is spinous. But though forming a 
perfectly natural and quite distinct group as to 
their structural character, they differ very wide- 
ly from one another in habit and economy; for 
while two, as we have hinted, live upon the ears 
of wheat, some live on rotting tulip and hyacinth 
bulbs and on half-decayed cow-dung, others in- 
habit the leaves of the Scotch pine, the buds of 
the sallow, and the flower-buds of the common 
hedge-mustard ; and many form downy excres- 
cences, somewhat similar to galls, upon ground- 
ivy, field wormwood, common campion, and some 
other plants. 
The wheat-midge, or British wheat-midge, or 
chief wheat-fly, Cecidomyta tritici, is very minute, 
scarcely exceeding the twelfth part of an inch in 
length, and resembling a small gnat or midge. 
The female has a pale ochreovs colour and is 
pubescent. Her eyes are intensely black, and 
coarsely granulated, meeting on the crown, and 
covering nearly the whole head. No part of the 
mouth is visible, except a short bilobed pilose lip, 
and two incurved palpi or feelers, which are 
four-jointed and slightly pilose. The antenne 
are stretched forward or curved upward, and in- 
serted close together in front of the face; they 
are as long as the body, pale brown, and clothed 
with longish hairs; and they comprise thirteen 
sub-elliptical joints, contracted round the middle 
and connected at the ends by a single thread, 
like a string of beads. The thorax is ovate and 
of a deep reddish ochre colour. The scutellum 
is transverse-oval. The abdomen is rather short 
and tapering to the apex, which is furnished 
with an ovipositor nearly thrice as long as the 
body, the sheaths at the base stout, the oviduct 
exceedingly slender. The wings are incumbent 
in repose, longer than the body, yellowish-white, 
and beautifully iridescent, pubescent, and cili- 
ated ; the costal nervure surrounding the wing, 
the subcostal short, the second extending to the 
margin, the third shorter, the apex forked. The 
two halteres or poisers are large and capitate. 
The six legs are long, slender, and nearly of equal 
length. The thighs and shanks are equally long. 
The tarsi or feet are five-jointed, the basal-joint 
minute in all, the second as long as the tibie, the 
IV. 
105 
remainder decreasing in length. The claws are 
very minute. The male is seldom seen; and his 
antenne are believed to be usually composed of 
twenty fine globose and somewhat remotely 
strung joints. The ovipositor of the female, not- 
withstanding its great length, is not seen, and 
would not be suspected by a stranger to exist in 
the ordinary condition of the fly; but is readily 
discovered by pressing the anus, or at the season 
of oviposition. It can be unsheathed by the in- 
sect at pleasure; and it comprises a long re- 
tractile tube or vagina, together with an aculeus, 
or pointed instrument like a sting, as fine as 
hair. 
The wheat-midge makes its appearance in 
wheat-fields just about the time when the ear is 
beginning to emerge from its leafy envelope, most 
commonly in the early part of June. It readily 
escapes the observation of persons ignorant of its 
character, or not looking out for it; but, to an 
intelligent observer, it may be seen on calm 
evenings, most frequently about eight o’clock, 
swarming about in small undulating clouds, in 
the manner of winter gnats and other kindred 
species, and it is occasionally seen also in the 
mornings and during the day. Each female usu- 
ally chooses as the receptacle of her eggs an ear 
just emerging from the sheath; and she intro- 
duces them by means of her ovipositor into the 
floret,—and while doing so, keeps her anus nearly 
at right angles with the margin of the floret’s 
glume. She is so engrossed with her occupation 
that she is not easily disturbed, and may even 
go on with her proceedings though a magnifying 
glass should be held close to her by an observer ; 
and she slowly introduces her ovipositor, and 
slowly parts with her eggs, and then cautiously 
and deliberately withdraws the instrument. So 
many as thirty-five flies may sometimes be seen 
at one time upon one ear; and some one or more 
of them may become almost exhausted in the 
effort to withdraw the ovipositor, or even may 
entirely fail to withdraw it, and remain fastened 
to the spot till devoured by some enemy. Mr. 
Kirby, after some vain attempts to see the eggs | 
pass through the long retractile tube, eventually 
witnessed that curious phenomenon. “I gathered 
an ear upon which some of the insects were busy,” 
says he, “and held it so as to let a sunbeam fall 
upon one of them, examining its operation under 
the three glasses of a pocket microscope. I could 
then very distinctly perceive the eggs passing 
one after another, like minute air- bubbles, 
through the vagina, the aculeus being wholly in- 
serted into the floret. I examined the process 
for full ten minutes before the patient little ani- | 
mal disengaged itself; and at last it was through 
my violence that she discontinued her employ- 
ment and flew away.” The eggs, in passing 
through the oviduct, receive a coating of glutin- 
ous matter which causes them to adhere firmly 
to the glumes; and they are deposited in small 
clusters, varying in number fromtwo to upwards 
2 Y 
