DIPTERA. — CECIDOMYIDES. 519 
with the exserted organs of respiration so remarkable in the larve of 
the preceding subfamily. According to Stannius, their spiracles are 
arranged as in the fungivorous larvae. * ( Observ. Mycetophila, p. viii.) 
The species of the genera Cecidomyia and Lasioptera are very 
numerous, inhabiting many different plants, some depositing their 
eggs in the young sprigs, others in the leaves, and others in the 
flowers, causing thereby either the production of galls similar to 
those produced by the Cynipidz, or the distortion of the flowers. 
De Geer has represented the transformations of several species (M/ém. 
tom. vi. pl. 25, 26, 27.), including Lasioptera Juniperi, and Cecidomyia 
Loti and Pini, the larve of which (jig. 125. 6.) are fleshy oval 
grubs, rather attenuated in front, without any exserted appendages, 
except that of L. Pini, which has short rudimental feet (which 
Bouché, however, did not find); the pup (fig. 125. 7.) resemble 
the imago, except in being of a much more contracted form, with 
the wings and legs very short and resting upon the breast, in distinct 
cases. One of the species produces galls on the willow, which Swam- 
merdam has accordingly described under the name of the Rose-wil- 
low. (Hill, Trans. p. 85, 86.) 
M. Macquart has noticed, however, that all the species do not pro- 
duce such alterations in plants. The larvee of C. bicolor Mezg., which 
are found upon the leaves of the mothwort, are amongst this number ; 
and they enclose themselves in a case, although M. Macquart could 
not determine whether this was the skin of the larva or a spun co- 
coon. M. Vallot also (who has observed the history of several species 
of these insects) describes the larve of a species, which reside on 
the under side of the leaves of Chelidonium majus, sucking the acari 
found in that situation, thus differing from all the rest. 
Some of the species in this genus are extremely injurious to the 
wheat crops both in England, Europe, and North America. Mr. 
Kirby has given ample details of the economy of one species, C. Tritici 
K. (Linn. Trans. vol. iii. iv. and v.), the eggs of which are deposited by 
the female in the centre of the corolla, where the larvae when hatched, 
perhaps by eating the pollen, prevent the impregnation of the plant, 
and thus destroy a considerable portion of the crop. Another species, 
still more destructive, known in America under the name of the 
= 
* Stannius noticed the curious connection which appears to exist in these two 
groups of insects — between the possession of spiracles along the sides of the bodies, 
and their habits of spinning a cocoon. 
LL 4 
