42 SOME INSECTS INJURIOUS TO TRUCK CROPS. 
insects were not observed to leave the vines unless disturbed, and the 
probability is that unless the food gives out they do not migrate dur- 
ing this season. It has been repeatedly observed by the hop growers 
of Chilliwack and Agassiz valleys that yards which were badly in- 
fested one summer would be almost free from beetles the next, while 
the adjoining yards which were not attacked the preceding season 
would be severely damaged. One explanation of this is that the 
beetles, having eaten up all the food remaining in the yards after the 
vines have been burned, migrate to the adjoining block, hibernate 
there, and emerge in the spring. As the beetles were not observed 
moving about during the spring and summer this is the only prob- 
able time of migration. 
Activities at night.—The beetles go into the bud scales or down 
under the clods at the base of the vine on cold nights, but when mild 
weather approaches they remain on the leaves. They were observed 
to move about slightly, but are very much less active than during the 
day. 
Flight.—When disturbed during warm weather the beetles occa- 
sionally spread their wings as they jump, and fly back to about the 
same place they started from. General flight is seldom indulged in, but 
during the last of April those which were disturbed by the Bordeaux 
spray circled around at an elevation of about 4 feet for a few minutes, 
then settled down. This was the only time when beetles were observed 
on the wing. 
Protection by concealment.—On cold spring days some of the beetles 
crawl down into the opening buds of the hop or nettle. Here they are 
protected from the weather and may feed upon the tender buds which 
are their choicest food. When the leaves have expanded beetles will 
be found on the under surface, and in very cold weather under the 
clods at the base of the vine. Although some are thus concealed dur- 
ing the active season, the majority remain on the upper surface of the 
leaves. 
Protection by locomotion.—When disturbed the beetles jump from 
the vine and fall among clods or rubbish where they are not readily 
seen. They do not feign death as some other beetles do, but spread 
out their legs, right themselves, and after a short pause, begin slowly 
to move about. The distance that they jump depends somewhat upon 
the height from which they start. Horizontally they can leap about 
a foot and a half, and about 10 inches in a vertical direction. 
SEASONAL HISTORY. 
LENGTH OF LIFE CYCLES. 
Judging from observations on the appearance of beetles in the 
field, the lengths of the life cycles of the spring and summer genera- 
82 
