DIPTERA. — CULICIDZ. 509 
in the females, however, they are generally very short. The head 
is small; the antenne are slender and filiform, as long as or longer 
than the thorax; they are described as 15-jointed * and plumose 
in the males, and as 14-jointed and pilose in the females, — the basal 
joint being subglobose and tubercular in form; the eyes are lunate ; 
the ocelli obsolete ; the thorax is oblong-oval ; the abdomen is long 
and slender, upon which the wings are incumbent when at rest; the 
latter have the nervures furnished with scales; the legs are very long 
and slender. 
The extreme irritation produced by the bite of the gnat is too 
well known even in our own country. The manner, however, in 
which the operation is effected is interesting: thirsting for its 
evening meal, the little animal enters our apartments, and instead 
of whirling, like the moths, round the light, it betakes itself to 
its employment; sounding an approach, however, by a tolerably loud 
humming +, which, in our chambers, at least, is often sufficient to 
banish sleep. Taking its station upon an uncovered part of the skin, 
with so light a motion as not to be perceptible when it alights (although 
it will not hesitate to make its attacks occasionally through our thick 
clothing), it lowers its rostrum and pierces the skin by means of its 
exceedingly slender needle-like lancets, which are barbed at the tips, 
and, as by degrees it pushes these deeper into the skin, the lower lip 
or sheath, in which they were enclosed when at rest, becomes more 
and more elbowed towards the breast, until the whole length of the 
* Tt appears to me that authors have erred in their computation of the num- 
ber of joints in the antenne of the male gnat. By Curtis they are described as 
15-jointed (including the large basal joint); that is, as possessing one joint more 
than the females, there being 12 short joints figured, succeeding the large basal 
globular joint and the long penultimate joint; and each of these 12 joints is fur- 
ther represented as verticillate at its extremity. Such is not, however, their real 
structure, the articulations occurring half way between the several whorls of hairs ; 
the consequence of which is, that the last whorl, instead of being at the apex of the 
short antepenultimate joint, is at a short distance from the base of the penultimate 
(18th) jeint, which is greatly elongated beyond the whorl: I bave clearly ascertained 
that there is no articulation immediately following the last whorl, the articulation 
by which the long penultimate joint is moved, occurring half way between the 
last and the penultimate whorl. Hence the number of joints is alike in both 
sexes, namely, 14. (Fig. 124.5. represents the penultimate and antepenultimate 
joints of the male antenne). - 
+ From a caleulation made by the Baron Caignard de Latour, communicated to 
me by M. Audouin, the gnat, during flight, vibrates its wings 3000 times in a 
minute. 
