THE SHARP-HEADED GRAIN LEAFHOPPER. 11 
jump at the slightest provocation. Because of this fact they are 
readily caught in the hopperdozer. A clump of tall grass was 
observed one day to be almost alive with adults, and although there 
was no wind and apparently nothing to disturb them, the adults 
suddenly hopped away, all at once. What caused the alarm was not 
determined. Adults, as well as nymphs, have the habit of dodging 
to the opposite side of a leaf or stem when approached by a foreign 
object. On days when there is a strong wind they remain in hiding 
close to the ground. They are most active during midday, and 
seldom may they be seen hopping about when dew is on the plants. 
As the sunlight recedes in the late afternoon they seek shelter under 
dried leaves and refuse, and at the base of the plant stems. While 
adults are most active on warm sunny days, during the intense heat 
of the summer they seek shade and damp places. From a series of 
observations it has been noted that they are more active on sunny 
than on cloudy days. Many adults, but not in such numbers as 
nymphs, can often be found feeding or resting on the same stem or 
leaf. They both rest and feed with head upward on the plant. 
GENERAL ACTIVITIES OF THE NYMPHS. 
Nymphs are even more active than adults, doing more running 
and dodging and less jumping about the plants. They seem to group 
themselves together; oftentimes 15 to 20 nymphs can be found on 
1 square inch of leaf surface, and it is because of this that their 
feeding becomes injurious to the plant. Mr. Wildermuth has ob- 
served that the nymphs commence feeding immediately after hatch- 
ing. The wind has a stronger effect upon the nymphs than upon 
the adults, and oftentimes a gust of wind will blow the nymphs 
several yards. They attempt to keep out of the wind by hiding 
but are rather easily blown from one plant to another, the thr*oats of 
young corn plants making a favorite hiding place. When resting the 
first-ins tar nymph assumes a characteristic posture, carrying its 
abdomen slightly curled up and over. The nymphs are very sensi- 
tive to heat, and the direct rays of the sun for more than a minute or 
two on hot days will kill these young stages. Many times they have 
been "observed to burst a bubble of excreta from the tip of their abdo- 
men when disturbed or approached by a foreign object, and Mr. 
Wildermuth suggests that this may be a means of defense as it is in 
the case of nymphs of the three-cornered alfalfa hopper (Stictocepliala 
festina Say). 
OVIPOSITION. 
A few days after the male and female adults have emerged from 
the last nymphal molt copulation has been noted to take place. 
In 10 experiments carried on in confinement the male died within 1 and 
2 days after copulation, although the females, in the same experi- 
