38 
except between the ninth and tenth. Compared with the previous 
stages, the larva is now more cylindrical, the prothorax being about 
twice the width of the head, mesothorax rather wider, and metathorax 
rather narrower. The first abdominal segment is very narrow still, 
the following segments increase in size to the fourth, which is the 
widest. Then they decrease gradually to the eighth. The ninth is 
very much narrower than the eighth and the tenth, half the width of 
the ninth and very long, terminating in two long points. If viewed 
in profile the head appears long, wedge-shaped, and partly retractile in 
the prothorax, which is much wider and deeper than the head. The 
segments gradually increase in depth to the second abdominal, and 
then slowly taper right away to the end of the terminal forks. The 
skin is very delicate and elastic, showing soft wrinkles whenever the 
larva moves about. The dorsum of the larva is fairly smooth, but 
there are w r ide lateral ridges ; the venter is also rather smooth, though 
it shows certain depressions. In the lateral ridges the very small 
spiracles are deeply embedded. They are very difficult to observe, but 
if we take a killed larva, cut it in half, and carefully roll out the con¬ 
tents of the skin, we can easily see the tracheal tubes and the branches 
from them to the spiracles. From the lateral ridges rise on certain of 
the abdominal segments—Liiders says from the first to seventh—small 
fleshy cones, which appear to be retractile. While the larva is in the 
mine these points may be seen in contact with the leaf cuticle above 
them. The eighth and ninth abdominal segments carry each four 
long, partly retractile, fleshy cones, two situated dorsally and two 
ventrally, so that, viewed in section, these segments appear like a 
four-rayed star. It is not always easy to make out the ventral cones. 
These eight long, fleshy points are kept in contact with the mine, and 
are of great service to the larva in keeping it firmly anchored in posi¬ 
tion, acting as a thrusting-block while the larva feeds. They are also 
used in progression, as Albarda remarks ( l.c .). Of the curious 
tenth abdominal Liiders gives such an excellent description that I feel 
bound to translate it (l.c., p. 26):—“Tenth of extraordinary length, 
fully as long as the three preceding segments, narrowed down towards 
the posterior, flat, with a longitudinal furrow, so that it appears as if 
it were formed out of two parts grown together; it terminates as a 
fish’s tail in two outwardly directed points.” Every writer on the 
subject says the larva has no feet, and I believe that to be true, except 
in the last stage, as the larva always appears so perfectly helpless 
when taken from the mine. Nevertheless, there are some very sug¬ 
gestive furrows and depressions on the abdominal segments, which 
usually carry prolegs in other larva?. When the larva mines on the under 
surface of a well-hidden leaf it is so perfectly colourless that it reminds 
one rather of a beautiful marine creature than an inhabitant of the 
dry land. The dark thoracic patch is then absent, and even the mouth 
parts are almost devoid of colour. 
Cocoon. —As soon as the larva has completed the work of mining 
out this space which is to become the cocoon, it stretches itself straight 
out, so that the head comes in contact with one end of this oval space, 
and the tail with the opposite boundary, the body of the larva lying 
parallel with the edge of the leaf. Now is the time to determine the 
sex of the larva, for the creature has not yet lost its transparency, 
though some of the internal organs appear to be gaining in opacity. 
