! 
= se 
* 
; THE PEAR LEAF-WORM. 9 
ie ,: 
-positor at right angles to the sheath (fig.4,@). The rhythmical sawing 
goes on for about 50 seconds more, the two surfaces of the leaf being 
forced apart to form a more or less oval cavity. The sawing ceases, 
and the portion of the ovipositor still outside the leaf is seen to be- 
come more opaque and greenish. This is due to the passage of the 
ege and the mucilaginous matter around it. The abdomen moves 
up and down slightly as the egg is forced into the cavity, and the 
saws are removed gradually. The actual depositing of the egg occu- 
pies about 30 seconds, and as soon as the ovipositor is iree the anten- 
nx, which have been practically quiet during the whole operation, 
immediately resume their rapid vibrations, and the fly moves to a 
SSS NNN ee Se 
== EY Zod 
— 
SS —— S « 
~ Eee SH 
Whi & 
i] 
aft 
“it Ug 
ly! 
‘ 
Si 
= 1 
(an 
y 
Pon 
= nae 
ts | 
Bye 
= = 
NN 
X 
AS EON i a ‘34 AI 
Fic. 4.—Ovipositor of adult female of the pear sawfly: a, Last three abdominal segments with 
ovipositor protruding; 6b, ventral view of last segments of abdomen with ovipositor retracted 
within its sheath; c, ventral view of ovipositor and portion of sheath, showing lateral ridges 
on inferior blades; d, single superior saw blade; e, single inferior saw blade; 0, ovipositor; 
s, superior saw blade; i, inferior saw blade; sh, sheath; cerc, cerci. All highly magnified. 
(Original.) 
new place. One female was observed to deposit 5 eggs in 20 minutes, 
but not all in the same leaf. 
BIOLOGY. 
There is one generation annually. In California, from observations. 
made in 1912 and 1913, it was found that adults issued during March 
and the first half of April, but before the middle of March very few 
emerged. In Washington, in the spring of 1915, practically all the 
adults emerged between the 1st and 15th of April. In both localities. 
the period of emergence probably varies more or less with the season. 
Immediately after issuing, the sexes presumably mate and the. 
females oviposit on young pear leaves. 
.§7170°—Bull. 488—16——2 
= 
