BACTERIAL WILT OF CUCURBITS. 6 
been tested so fully, but sufficient work has been done to show that 
they are also capable of direct wilt transmission. 
TRANSMISSION FROM RANDOM COLLECTIONS OF BEETLES. 
Collections of striped cucumber beetles and 12-spotted cucumber 
beetles taken at random in the fields have given widely varying 
results as to wilt transmission according to time of year, prevalence 
of wilt, amount of territory devoted to cucurbits, and length of time 
the beetles had fed since attaining the adult stage. In eastern Long 
Island from the first collections of early spring only an occasional 
striped beetle has proved to be a wilt carrier. Later in the season 
some collections have shown a large percentage capable of spreading 
the disease. For example, on September 1, 1916, striped beetles 
were collected at random in a cucurbit field and several put into each 
of four beetle-proof cages containing healthy cucumber plants. Many 
of the vines in each of the cages contracted bacterial wilt, so that at 
least one of the beetles introduced into each cage must have been a 
wilt carrier. About two weeks previously six beetles collected in the 
same locality failed to give infection. In this locality late cucumbers 
constitute one of the main crops. 
However, in the trucking sections around the District of Columbia 
late cucurbits are rather the exception, most of these crops being 
planted there in early spring. In that locality random collections 
from the field have given a much smaller percentage of infection. 
During the summer of 1917, at Tuxedo, Md., from fire to seven large 
insect cages were kept constantly as storage cages for both species of 
cucumber beetles. Healthy plants grown in the cages and healthy 
potted cucumber plants brought frequently from the greenhouses at 
Washington, D. C, were kept in the cages as food for the beetles. 
Collections of beetles made at frequent intervals from fields where 
wilt was present were placed in these cages, but throughout the season 
only two cases of wilt occurred in these cages. In many instances 
the beetles were taken directly from wilting vines. 
Twelve striped beetles, among the first of the season found, were 
collected May 20, 1918, in an early cymling field at Kenilworth, D. C. 
Careful search over the field failed to reveal any cases of wilt. These 
beetles were caged for four days with 10 cucumber seedlings, after 
which the plants were held for observation in a beetle-free cage. On 
June 4 two of the ten plants had wilted. Cultures were made and 
Bacillus tracJieiphilus was isolated and tested by successful inocu- 
lations. 
In a large collection of striped beetles made at Norfolk, Va., about 
October 1, 1916, wilt resulted in one out of several cages among which 
the beetles were distributed. 
In most instances only a very small proportion of the cucumber 
beetles present in a field actually carry infection. 
