July 1, 1925 
Overwintering and Dissemination of Cucurbit Mosaic 
13 
Table IV. — Transmission of cucurbit mosaic from Micrampelis lobata to healthy 
cucumber plants by Diabrotica vittata 
Date 
Cage 
Source of infection 
Number 
of beetles 
in cage 
Number 
of cucum¬ 
ber plants 
in cage 
Number 
of mosaic 
plants 
Date 
observed 
May 6,1919_ 
1 
1 mosaic Micrampelis plant in cage 
with healthy cucumbers. 
25 
6 
3 
May 15,1919 
Do 
2 
__do__ . _ 
<*0 
6 
0 
Do. 
June 14,1919... 
1 
3 mosaic Micrampelis plants in cage 
with healthy cucumbers. 
30 
5 
2 
June 30, 1919 
Do 
2 
_do...... 
a 0 
5 
0 
Do. 
June 11, 1920... 
1 
_do.... 
20 
8 
3 
June 30,1920 
Do 
2 
do .. _ _ 
20 
8 
2 
Do. 
Do 
3 
.do.... 
20 
8 
1 
Do. 
Do_ 
4 
_do-- 
“0 
10 
0 
Do. 
a Control. 
Table V.— Transmission of cucurbit mosaic from Micrampelis lobata to healthy 
cucumber plants by Diabrotica 12-punctata 
Date 
Cage 
Source of infection 
Number 
of beetles 
in cage 
Number 
of cucum¬ 
ber plants 
in cage 
Number 
of mosaic 
plants 
Date 
observed 
July 10, 1919.... 
1 
3 mosaic Micrampelis plants in 
cage with healthy cucumbers. 
25 
6 
2 
July 25 1919 
Dn 
2 
.do__ 
25 
6 
3 
Do. 
Dn 
3 
.do_ _ 
a 0 
6 
0 
Do. 
Aug. 15, 1920... 
1 
1 mosaic Micrampelis plant in cage 
with healthy cucumbers. 
30 
6 
3 
Aug. 29, 1920 
Dn 
2 
25 
* 4 
1 
Do. 
Dn 
3 
38 
10 
3 
Do. 
Do_ 
4 
a 0 
8 
0 
Do. 
* Control. 
Although the beetles used were first tested by allowing them to 
feed on healthy plants, there is a remote possibility that they may 
have carried infection from outside sources. This seems unlikely, 
however, as the experiments with Diabrotica vittata were conducted 
early in the spring at a time when no cultivated cucurbits had ap¬ 
peared in the vicinity, so that the only probable source of infection 
would have been mosaic plants on which the beetles had fed before 
they were collected. Other experiments, however, were in progress 
at the same time, in which beetles collected in the open were fed 
on healthy cucumber plants, but no infection occurred in such 
cases. The experiments with Diabrotica 12-'punctata were necessarily 
conducted at a later date, as this species does not appear in any con¬ 
siderable numbers until after cucumbers in the field have passed 
the seedling stage. No mosaic was found on cucumbers, how¬ 
ever, until some time after the insects had been collected, so that 
mosaic wild cucumber plants were, in all probability, the only 
source from which the insects may have carried infection. The 
preliminary tests with these insects, however, seem to have eliminated 
this possibility. 
Importance of the Striped Cucumber Beetle in the Transmission $>f 
Mosaic from the Wild Cucumber 
The striped cucumber beetle is apparently of greater importance 
than either the 12-spotted beetle or the cucumber aphis in carrying 
