374 Watter N. Hess 
This larva may undoubtedly be recognized by its habitat in the cambium 
of recently killed pine trees, by its relatively large size when mature, 
and by its broad, flattened head and body. 
The mouth parts of the larva 
Since these larvae closely resemble in appearance the flat-headed borers, 
the prothorax and the head are very wide and flat, resulting in a rather 
broad, short clypeus and labrum (fig. 63). The clypeus (Cl) is very wide 
at its basal part but tapers anteriorly to 
join the labrum. The labrum is about 
twice as wide as it is long, and bears 
on its dorsal side many long bristles and 
sense pits. 
The mandibles (fig. 64) are broad and 
heavily chitinized, and bear near the 
apices three rather sharp cutting teeth 
which fit them for both cutting and 
chewing. 
The maxillae of the larva (fig. 65) are 
of a much simpler type than those of 
the adult. The cardo (C) is a distinet 
sclerite, triangular in shape. The 
stipes (S) and the lacinia and galea 
(LG) are not differentiated but are 
represented by one segment;. near the 
Fic, 65. MAXILLA, VENTRAL VIEW apex on the inner margin are. many 
mc: EEO ees mone ease long bristles, which probably repre- 
sent the region of the future lacinia. 
The palpus (P) is three-segmented. 
The labium (fig. 66) is large and covers the greater part of the lower 
side of the head. The submentum (SM) is broad and short. The 
mentum (M), while narrower than the submentum, is broad and flat. 
It bears the ligula (L), from which arise the two-segmented labial 
palpi (P). The greater part of the surface of the labium, but more 
especially the anterior edge of the ligula, bears numerous long bristles 
and sense pits. 
