572 MISC. PUBLICATION 657, U. S. DEPT. OF AGRICULTURE 
inches below the surface. Either hand picking of the infested stems as 
soon as noticed, or spraying the ground beneath the trees with kero- 
sene emulsion about June 15, when the larvae are entering the ground, 
is the most practical method of control. 
The striped alder sawfly (Hemichroa crocea (Fourcroy) ) has also 
been designated as H. pallida Ashm., H. dyari Roh., H. washingtonia 
Roh. & Midd. ., and Dineura americana Prov., but in 1937 Ross (367) 
placed these in synonomy. The full- -erown larva is about 44 inch 
long, the head is shiny black. The body is yellowish and marked on 
each side by a broad dark-brown subdorsal stripe extending from the 
second thoracic segment to the tenth abdominal segment, and with two 
broken subspiracular stripes composed of irregular blotches and dashes 
extending almost to the ninth abdominal segment. The newly hatched 
larva is pure white, the dark markings becoming visible in the second 
and third instars. This species was ‘first deser Shai from Europe, but 
has apparently been present in North America a great many years. It 
is known to occur through many of the Northeastern States and west- 
ward into Oregon, and in Canada apparently ranges from Quebec 
to British Columbia, feeding on various species of alder and occa- 
sionally birch. Reports indicate that occasionally it causes severe 
defoliation of alders in British Columbia and also in some of the 
Northeastern and Lake States. 
There are two generations annually. The winter is passed as a pre- 
pupal larva in its cocoon, which is very thin and formed within a cell 
made by cementing together particles of sand and earth a few inches 
beneath the surface of the ground. Adults emerge during the latter 
half of May, and the eggs are deposited on the under surface of the 
leaves in slits nade in the sides of the midribs. Larvae of this genera- 
tion become full grown in July. Late in July and early in ‘August 
the adults of the next generation emerge and their larvae may be found 
in August and September. The larvae are gregarious and usually 
devour all but the midrib and larger veins of the leaves. 
The full-grown larva of the mountainash sawfly (Pristiphora gen- 
iculata (Hte. )) is 5 to 834 inch in length. The head and legs are yel- 
low orange, ‘the eyes are black, and the body is yellowish, w ith all seg- 
ments except the last marked with black spots of uneven size and 
shape. The spots are arranged in more or less irregular longitudinal 
rows with four rows on each side of the body (two above and two below 
the line of spiracles), and two broken rows (spots usually absent from 
back of abdominal segments 2 to 5, inclusive) down the middle of the 
back (fig. 161). The young Tinea is greenish white, with head and 
legs blac 1k, and the body marked with black dots. 
"This species was first described from Europe in 1840 by Hartig. 
Although the first definite record of its occurrence in the United States 
was in 1926 from specimens collected at Haines Falls, N. Y., entomol- 
ogists differ in opinion as to whether it is of European origin. In 
1928 and 1929 it was first reported as seriously defoliating mountain- 
ash in widely separated localities in Massachusetts, New York, and 
Vermont. Each year since 1929 this species has been more or less 
abundant in many localities where mountain-ash commonly grows, and 
is now known to occur in New Jersey, New York, and throughout 
New England. In Canada it is found in the Maritime Provinces, 
