ALDER SAW-FLIES. 633 
20. Cimbex americana Leach. 
This Cimbex occurred on the alder at Brunswick, September 3. 
Larva. — Head not so wide as the body, somewhat excavated in front ; pale amber 
with a whitish bloom ; eyes large, black ; body moderately thick ; eight pairs of 
abdominal legs ; the segments with coarse wrinkles, about five to each segment. A 
black conspicuous narrow dorsal line, fading out before reaching the end of the body. 
Across each segment two rows of prominent raised white warts, which become more 
numerous down on the side. Tail curved up to one side. Length, 19 to 20 mm . 
21. Selandria-like larva. 
(Plate iv ; fig. 13, 13a.) 
This false caterpillar occurred on the alder September 3. 
Larva. — Body flat ; thoracic legs spreading out ; body bottle-green above, with 
obscure, paler warts; much paler low down on the sides and beneath ; body serrated ; 
it differs from the species common on the oak and poplar, in the head being rust- 
thrown above, paler in front, not red on each side. Supra-anal plate small, clouded 
-above. Length, 13 mm . 
22. Nematus ? sp. 
This is the most common saw-fly larva observed on the alder. It 
first appears early in July and remains on the bushes until early in 
September. The eggs are laid in pairs, twenty to forty pairs on the 
under side of the midrib of the leaf. In one example there were about 
forty pairs of gashes, which are slightly semicircular, opposite to each 
other, and sometimes so near as to run together. I have found two 
broods on two leaves, July 23 ; the leaf had been two-thirds skeleton- 
ized. The larvae apparently, on hatching, walking to the end of the leaf, 
and beginning at the end, gradually eat out the parenchym between 
the secondary and smaller veins. At first the larvae have yellow heads, 
and two faint lateral double rows of black spots ; the adults have' black 
heads, and a distinct lateral black line, the abdomen being curled up 
snail-like. (Figs. 210, 211.) 
Larva after first molt.— Length, 4 mm . Head wider than the body, deep gamboge yel- 
low, with black eyes ; bristly ; body greenish ; papillated, with a double lateral 
row of dark elongated flattened tubercles. 
Larva fully groivn. — Head jet-black, with short scattered hairs, not quite so wide as 
the body, which is long and narrow, the end curled up or raised over the back ; sur- 
face wrinkled and rough, with small piliferous warts, the hairs short ; a distinct 
lateral black line, below which is a double row of black elongated tubercles. Length, 
10 mm . 
23. Nematus sp. 
This saw-fly larva was observed on the alder in September, i-n Maine. 
Larva. — Head full and rounded, red, black in the middle above. Two large and 
one small fleshy prothoracic granulated acute tubercles ; four black very sharp fleshy 
