118 MODERN CLASSIFICATION OF INSECTS. 
pressed, terminated by three or four nearly equal teeth, and furnished 
with a large horny lobe ( fig.72. 20.). The action of these jaws must 
be remarkable, because the acute edge of one is brought into con- 
tact, when at rest, with the broad extremity of the other. The max- 
illee are small, and terminated by three lobes; the inner one is oval 
and strongly setose ; the outer one is very minute and exarticulate ; 
whilst the intermediate one, which appears to me to be the analogue 
of the palpus, is broad at the base, and terminated by a small narrower 
part, which I believe to be articulated both at its base and in the 
middle (fig.’72. 21.). The figures given by Hartig of this organ 
(tab. 8. fig. 26. b.), give no notion of its true form. The lower lip is 
fleshy, transverse, and produced considerably within the mouth; it is 
provided at the sides with a pair of minute 3 ? -articulate palpi ( fig. 72. 
22.). Each of the three anterior segments of the body is furnished 
with a pair of minute exarticulate legs. The abdominal segments are 
destitute of prolegs, which are replaced by fleshy protuberances, and 
the terminal segment of the body is large, and armed with a horny point. 
In the larva state these insects reside in the interior of trees, which 
they perforate in various directions, often causing great destruction in 
the pine forests, of which the larger species are inhabitants.* When 
full grown, these larvee are stated by some authors to form a slender 
silken cocoon, mixed with chips of wood and excrement, at the end 
of their burrows, and in which they undergo their final transforma- 
tions. The pupa greatly resembles the imago, having the limbs laid 
along the sides of the body and breast. When the transformations of 
the insect take place in the summer, the imago is produced in the 
space of a month; but if the larve are not full grown until autumn, 
the fly does not appear until the following summer. 
The perfect insects are amongst the largest in the order, and make 
a considerable humming on the wing, like the humble bee ; whence 
Mr. Macleay, who formed them into an osculant order, between the 
* Mr. Raddon forwarded to the Entomological Society specimens of U. Juvencus, 
accompanied by specimens of the wood of a fir tree from Bewdley Forest, Worces- 
tershire, perforated by this insect. Of this tree, 20ft. were so intersected by the 
burrows, that it was fit for nothing but fire-wood; and being placed in an out- 
house, the perfect insects came out every morning, five, six, or more each day. The 
females averaged one in twelve for the first six weeks, but afterwards became more 
plentiful, and continued to make their appearance until the end of November, 
females only being produced during the last two or three weeks. ( Trans. Ent. Soc., 
vol. i. p. 85. App. ) 
