216 
MR WALTER RITCHIE ON THE STRUCTURE, BIONOMICS, AND 
brown in colour. The body is deeply wrinkled, with fine hairs scattered over it. 
The larva is made up of the chitinous head-piece and thirteen segments, the first 
three segments forming the thorax and the remaining ten the abdomen. The 
thoracic segments are slightly larger than the abdominal ones. The 8th and 
9th abdominal segments are much smaller than the others, while the 10th is 
made up of three lobes around the anus. The 1st thoracic segment and the first 
eight abdominal segments bear each a pair of spiracles. The full-grown larva 
measures on an average 4'5 mm. 
The Head (fig. 9). 
The head of the larva of M. minor, viewed from above with the aid of a binocular 
microscope, shows the following In the centre of the chitinous head-piece may be 
seen a triangular region called the frons (f)] at the anterior corners of the triangular 
fronS lie the antennae (a.), each single-jointed and sunk in a pit ; along the anterior 
base of the frons is a narrow area, the epistome (e.), composed of a thick band of 
chitin extending from one antennal pit to the other and supporting anteriorly the 
clypeus ( c .) ; anterior and jointed on to the clypeus is the labrum (l.). 
On either side of the frons posteriorly lies the epicranium (ep.), divided 
into two by the frontal sutures ( f.s .) anteriorly, and by the epicranial suture 
posteriorly ( e.s .). 
Examined from above, the mandibles (m.) can be seen in part projecting beyond 
the labrum ; their greater part, however, is overlapped by the labrum. Each 
mandible shows three prominent teeth, is dark brown in colour, and is highly 
chitinised. 
As the shape of the epistome is often used as a means of distinguishing one 
species of larva from another, I have figured an enlarged view of this region of the 
head (fig. 10). 
Looking at the head from the ventral side, one can see the maxillae (fig. ll). 
The 1st maxillae are the outermost parts in this view and are- composed of three 
portions : posteriorly the cardo (C.), anterior to this the stipes ( S .), which bears the 
three-jointed maxillary palp ( M.p .) and a few bristles, and thirdly, the lacinial lobe 
(l.l.), which has fairly strong bristles. . In the centre is the labium or fused 2nd 
maxillae, which comprises the mentum (M.) anteriorly, bearing two labial palps (l-p.), 
each of which is two-jointed, and the ligulae ( l .) in the middle line. The sub- 
mentum ( S.m .) is posterior to the mentum, while still more further back is the 
submental area ( S.a .). 
The Thorax. 
In a side view (fig. 8) of the thorax of the larva we have the prothoracic segment 
lying just behind the head, next the mesothoracic, and next the metathoracic 
segment. These are the three largest segments of the body. 
