124 
Ohsercalions on the various Imecfs 
is very pointed, with two black lines on the crown, and two horny 
spines or jaws at the mouth : the body is composed of about 
twelve segments, thickening towards the tai], which is blunt and 
rounded, with two brown spots, being the tips of two tubercles : 
they are about 5 lines, or not quite ^ an inch long (fig. 26 p). 
VVlien full-grown in November, I placed them, with the diseased 
root they inhabited, in a garden-pot with mould, and in the fol- 
lowing April a great number of female gnats had hatched, but 
were all dead ; they therefore must have come forth at an earlier 
period : the empty pupae-cases were lying about, but I could not 
find one unhatched, which I am led to regret, because even De 
Geer was unacquainted with the economy of this insect ; a figure, 
therefore, of the pupa would have been interesting. The empty 
cases were pale dirty ochreous, exhibiting the forms of the dif- 
ferent members of the imago ; they were a little arched, the tail 
was pointed, with two parallel spines at the tip, and two short- 
pointed teeth above them. The gnats are often seen resting upon 
the inside of our windows in the winter, especially after the break- 
ing up of frosts, and in calm days they fly- in troops in fields and 
gardens, dancing together in the air without separating, and dur- 
ing the severest frosts these fragile flies, which are so delicate 
that one would imagine a breath, much more a northern blast, 
would annihilate them, may be found standing upon tlie sides of 
walls in damp gardens as unaffected apparently as in the finest 
days of spring. Six species have been found in England;* and 
one of them has been bred from putrid Fungi by Mr. Haliday. 
These gnats belong to the Order Diptera, and to the Family 
TlPULiD^. ; they form a Genus called by Meigen Triciiocera : 
the species infesting the turnips is named by the Baron De Geer 
7. T. hiemalis, the Winter turnip-gnat (fig. 27). The males 
are smaller than the females, and are distinguished by the struc- 
ture of the tail : they are of an ash-colour ; the head is small and 
globular, with two lateral black eyes ; the neck is slender ; the 
mouth forms a little beak; the feelers are distinct, incurved, and 
five-jointed ; the horns are longish, pubescent, setaceous, being 
very slender at the tips, composed of many joints, the two basal 
globose, third the longest, the remainder elongated : thorax oval, 
cinereous, with four fuscous stripes ; body cylindric, pubescent, 
the apex obtuse in the male, with two incurved appendages, 
forming a pair of forceps ; more conical in the female ; with two 
parallel black hooks bent down like a claw at the apex, and 
forming the ovipositor ; wings incumbent in repose, ample, much 
longer than the body, glassy, iridescent, slightly stained with 
yellow, having numerous longitudinal nervures, forming one dis- 
Cartis"s Guide, Gen, 11G5. 
