58 BULLETIN Sl% IT. S. DEPARTMENT OE AGRI CULTURE. 
within the cage was not disturbed and the natural covering of grass 
and leaves was left intact. The insects were fed on the fruits and 
leaves of mosaic cucumber plants as long as these could be secured. 
Later in the fall seeds of the wild cucumber (Micrampelis lobata) 
were scattered in all the cages, in order to furnish plants for an 
immediate test of the beetles when they emerged in the spring. 
On June 17, 1918, two beetles appeared in each of two cages, 
but no others were found in any cages during the rest of the season. 
The beetles which appeared were allowed to feed on the wild cucum- 
ber plants present in the cages, but were not otherwise tested. The 
writer did not observe these plants after June 22, but other observers 
report that no mosaic appeared. So far, therefore, the tests of beetles 
hibernated under artificial conditions have given no evidence that the 
insects are concerned in the overwintering of the disease. 
Natural hibernation experiments. — Frequent observations were made 
in the fields at Madison, Wis., during the spring of 1917, and the first ^ 
insects which appeared were collected and tested for mosaic infection. 
The first beetles were noted on May 25, the insects suddenly appearing 
on seedlings of Micrampelis lobata growing in a sand pit about 50 
yards from the main experimental plats of 1916 and 1917. About 
250 of these beetles were collected by the writer between May 25 
•and June 5, and varying numbers of them were placed on healthy 
cucumber plants under cages in the greenhouse. In this work 83 
plants were used, and the insects were allowed to remain on them 
for two weeks, but no mosaic infection occurred. In addition to 
these tests, 60 small cucumber plants were set out in the sand pit 
and in adjacent fields at points where they would be likely to attract 
the beetles. Nearly all these plants were somewhat injured by the 
insects, but all remained healthy until after mosaic had developed at 4. 
other points in the locality. 
The first beetles to appear in the spring of 1918 were again tested 
in the same manner as in 1917. About 400 striped beetles were 
collected between May 15, when they first appeared, and May 28. 
These were placed under cages with healthy cucumber plants in the 
greenhouse, 98 plants being used for the tests. About 100 beetles 
were also collected at Plymouth, Ind., during the latter part of May 
and similarly tested on 25 healthy cucumber plants. No mosaic 
appeared on any of these plants, however, although they were 
observed for three weeks. Young plants were set out in the sand 
pit as in 1917, but no signs of mosaic developed, although the plants ^ 
were exposed to the beetles from May 30 to June 20. 
Field observations in 1917. — The striped beetles were very numerous 
about Madison, Wis., during June and July, 1917, and the young 
cucumber plants, which appeared about June 25 on the experimental 
plats, were severely injured by thorn. No mosaic was found in any 
