affecting Carrots and Parsnips. 
191 
pulp of the leaf, causing large blisters upon them ; and when two 
or three larvae are feeding on the same leaf, the blisters unite and 
form large discoloured patches (fig. 22), for the inflated skin, 
which at first is pale or whilibh, as it dries becomes yellow or 
tawny, and the maggot may be distinctly seen when the leaf is 
held up to the light (fig. 23). Thus the leaves are disfigured 
from Midsummer to near Christmas, and as the maggots arrive 
at maturity, they either change to pupae in the blisters amongst 
the excrement of the larvae, or pierce the skin, and falling upon 
the earth undergo their transformations in the soil, and from these 
the flies are again produced. 
These two-winged flies belong to the Order Diptera, the 
Family Muscid^e, and the Genus Tepuritis : the species was 
named by Fabricius * 
T. Onopordinis, from its frequenting the cotton-thistle (OrtO^or- 
dum Acanthiinn). It varies in the spots of the wings, which has 
led the same author to describe a variety under the name of T. 
CentaurecE, from its resorting to another genus of composite 
flowers. The eggs I have never seen, but the larvae (fig. 24) are 
nearly 4 lines long, shining pale green ; they look fat and some- 
what transparent, so that the alimentary canal is visible along the 
back, forming a darker line (fig. 25, magnified) : it is attenuated 
to the head, which is pointed, and the tail is blunt and tubercled ; 
the body is divided mto segments, and the sides are wrinkled. 
The chrysalis (fig. 26, f. 27, jnagnified) is horny, pale-yellow, 
glossy, and oval ; the segments deeply impressed from the contract- 
ing of the maggot, of which this is only the indurated skin, for 
maggots do not cast their skins as caterpillars do. When one 
of the pupae was opened in February, a delicate nymph of a 
beautiful green colour was seen inside ; and when the fly is per- 
fectly matured, it elongates its body, which is filled with a thick 
cream-like fluid or meconium ; the pupa-case cracks at the head 
and through the opening the fly walks forth. 
12. T. Onopordinis. The Male is about 2 lines long, and the 
wings expand 5 or 6 lines: it is shining, tawny, with a few black 
bristles scattered over the head and thorax : the lower part of the 
face and the 2 little drooping horns are yellowish ; the latter are 
3-joinled, with a black bristle ochi eous at the base, attached to 
the back of the 3rd joint, which is oval ; at the lower part of the 
face is a large cavity to receive the mouth, which is composed of 
a fleshy hairy bilobed lip, 2 long hairy fleshy feelers, and a short 
strong horny pointed tongue ^-j- the lateral compound eyes are 
remote, ovate, and deep green, and there are 3 little simple eyes 
* ' Entom. Syst.,' vol. iv. p. 360. Trypeta, Meig., vol. v. p. .316. 
•|- Vide Curtis's ' Brit. Ent.,' pi. 241, lor dissections. 
