THE IMPORTED PINE SAWFLY. 9 
experiments both sexes were obtained in the progeny, while, as will 
be stated farther on, in parthenogenetic experiments only male adults 
were obtained, indicates that mating is a regular occurrence. 
OVIPOSITION. 
The eggs are laid in the needles of the pine and the adults emerging 
from their cocoons early in the year oviposit in the old or last year's 
needles, while the adults emerging later in the year lay their eggs in 
the needles of the current year. The following note, made in obser- 
vations on the habits and activities of the adults in the life-history 
and seasonal-history cages, shows the increase in attractiveness of 
the current year's needles. 
All the females, except the one emerging at the latest date, i. e., June 23, 1916, laid 
their eggs in the old or grown needles, but this female, possibly because of the advance 
of the younger needles, delayed her oviposition several days and then apparently 
first attempted egg laying in these new leaves. After two slits or thrusts, possibly 
having succeeded in laying an egg in one of these, she began on the old needles ana 1 
finished her work on them. 
This note seems to indicate a preference for the young needles 
which were still too small for this female to oviposit in them. 
The following account, taken from cage notes made during these 
experiments, gives an accurate description of the method of ovipo- 
sition : 
The female begins laying eggs near the base of the needle and works toward the 
tip, making a new incision for each egg. In oviposition the mandibles usually close 
upon the needle; the antennae extend forward and are usually quiet and the wings 
are folded, at rest on the back. The ovipositor (Fig. 6, b, c) is exserted from between 
the right and left hajves of the sheath, forming an angle of about 60° with the needle. 
It is worked into the needle and straightened until as it disappears it forms a right 
angle with the needle, saw edge forward (Fig. 6, a). 
The posterior margin of the seventh sternite is membranous and is produced 
medianly to form a sort of trough (tr) for conveying the eggs into the slit prepared for 
them. The sides of the trough are supported by a pair of diverging chitinous pieces 
or more rigid areas. This trough during oviposition is immediately in front of the slit 
that is being cut and serves as a support to the abdomen, maintaining a constant 
distance between body and needle and contributing to a rigidity and firmness of the 
base of the working parts in their relation to the needle. Posterior to the trough and 
basad of the sheath proper there is a pair of rather small rectangular plates or trowels 
(0 (Fig. 6, d), one plate at each side, attached to the base of the basal portion of the 
sheath (sh 1 ) and appearing similarly attached to the base of the lance (le). These 
plates were observed for the first time in this insect and are not found in Neodiprion 
lecontei, which belongs to the same subfamily, nor has the writer been able to discover 
similar developments in sawflies outside of the Diprioninae. The function of these 
plates or trowels is apparently to support and mold the torn needle fiber into walls 
and cover for the egg pocket. The sheath (sh 1 and sh 2 ) is posterior to these plates (t) 
and its right and left halves cover respectively the right and left sides of the needle at 
the point of incision. During the sawing there are alternate contractions and expan- 
sions of the pleurum of the ninth urite which cause the sheath to flex or bend at the 
juncture of the basal (sh 1 ) and apical (sh 2 ) portions, and a side-to-side oblique move- 
ment of the trough (tr). The saw is worked or dragged until the trough (tr) reaches the 
mesothoracic legs. The puncture is then complete and the abdomen is slightly ele- 
vated. The trough (tr) and the trowels (t) are now pushed back together, smoothing 
off the torn fiber at the mouth of the pocket and bringing together the walls of the 
cavity at its opening. The saw is withdrawn at the same time. It is not visible 
except through the needle tissue, being hidden by the trowel (t), and its withdrawal 
is accomplished or accompanied by a backward, upward folding movement. The 
entire egg-laying process consumes about two minutes. 
53373— 23— Bull. 1182 2 
