1917] Hungerford—Life-History of Mesovelia mulsanti White five 
arranged in such a way that the front surface is concave forming a 
wide groove, reminding one, when in action, of the tip of an apple 
corer. Upon dissection it is seen to be made up of three parts, 
two lateral shafts that are strongly chitinized and toothed or 
serrated along the lower portion of their lateral margins and a 
broader central plate (see Pl. I, Figs. 14 and 15). The lateral 
shafts are attached to the flat plates of the abdominal wall. The 
central portion is in reality made up of paired parts attached to 
the median pair of sclerites ‘that serve as the valves or shields for 
the ovipositor. ; 
The manipulation of this instrument during oviposition may be 
observed any time during the spring, summer or autumn by con- 
fining a number of mating insects in a petrie dish containing only 
clear water and some food. After being thus deprived for a couple 
of days of materials in which to place their eggs they. will gather 
about a small bit of sedge stem or cat tail leaf supplied them, and 
most eagerly set about the business of laying eggs. The writer 
has seen as many as eight thus employed about a portion of sedge 
stem one and one-half inches long and has had ample opportunity 
to watch the process under the binocular. | 
The female frequently explores the stem with the tips of her ° 
beak and antennz if indifferent in the matter, but if eager to 
oviposit, she mounts the stem without delay, raises the abdomen 
slightly, unsheaths the ovipositor and turns its tip down to the 
surface of the stem. At times the surface is tested out at several 
points—again if the first point of contact is favorable, the tip is 
caused to quiver back and forth till it gains a footing, and then 
rocking the body slightly from side to side the entire drill is caused 
to rotate or twist back and forth on its axis—rapidly at times, or 
again more slowly as may suit the necessity of the work, until a 
hole is effected and the ovipositor is buried to its base. During the 
deeper drillings the longitudinal alternate thrusts of the drill parts 
are apparent. The first part of the operation at least involves 
much the same sort of a motion as one employs in making a hole 
with a gimlet or awl.! 
1In addition to the twisting motion and the alternate thrusts of the stylets there is yet an- 
other. It is the expanding or spreading of the drill parts during the enlarging or reaming out 
of the hole. 
