16 
Journal of Agricultural Research 
Vol. XXXI, No. 1 
the mosaic Micrampelis for one-quarter mile to the shore of Lake 
Mendota, and one-half mile east and west. This area was carefully 
inspected to insure the removal of wild host plants, and it was 
believed any infection which occurred in the plats must be carried 
over a distance at least equal to that which separated them from 
the known source of mosaic. 
These experiments were conducted on the same plan during 1920 
and 1921. The number of plats was reduced in 1921, but those 
remaining occupied approximately the same positions as in 1920. 
Frequent inspections were made to note the first appearance of 
mosaic and as soon as it appeared in a plat all of the plants, both 
mosaic and healthy, were at once removed, except in one case which 
will be noted later. This was done to prevent the disease from 
spreading from plat to plat. The various dates of infection in the 
several plats are shown in Table VII. 
Table VII .—Results of experiments to determine distances over which mosaic 
infection may he carried by insects from Micrampelis lohata to cucumber 
1920 j 
' 1921 
Plat 
Dis¬ 
tances 
from 
mosaic 
Micram¬ 
pelis 
Date 
beetles 
appeared 
in plat 
Date 
mosaic 
appeared 
in plat 
Plat 
Dis¬ 
tances 
from 
mosaic 
Micram¬ 
pelis 
Date 
beetles 
appeared 
in plat 
Date 
mosaic 
ap¬ 
peared 
in plat 
la «... 
Yds. 
1 
140 
175 
225 
350 
350 
500 
June 11 
_do_ 
June 27 
July 16 
Aug. 10 
Aug. 2 
July 23 
Aug. 2 1 
July 28 | 
1 
la_.... 
Yds. 
1 
175 
225 
350 
500 
June 8 
_do_ 
June 21 
Aug. 28 
July 17 
Aug. 18 
June 30 
2_ 
26_ 
36_ 
...do. 
__.do. 
_do. 
3c.___ 
—do_ 
June 10 
—do. 
4c... 
4 d _ 
5d. _ 
5e _ 
6__ 
—do 
7e _ 
___do. 
• Letters indicate plats in approximately same location in 1920 and 1921; 1920 plats planted May 28 
1920; 1921 plats planted May 28, 1921. 
In both years many striped and a few 12-spotted beetles were 
already present when the seed was planted and the insects appeared 
in all the plats while the plants were still in the seedling stage. In 
both 1920 and 1921 the plants in plat 1, which was directly adjacent 
to the mosaic wild cucumbers, were infected at an earlier date than 
plants in any of the other plats. Observations showed that there 
were frequent migrations of beetles from the wild cucumbers to this 
plat. In both seasons there was an irregularity of infection as related 
to the distance from the supposed source of mosaic infection on 
Micrampelis. This is noticeable in plats 2 and 3 of tl|e 1921 experi¬ 
ment, which were in an open field at a distance of approximately 50 
yards from one another. Infection in plat 3 occurred on July 17, 
while in plat 2, which was nearer the wild cucumbers, the disease did 
not develop until August 28. The same fact is even more evident 
m the most distant plats of the two experiments, in both of which 
the disease developed much earlier on plants at a distance of 500 
yards from the mosaic Micrampelis plants than in plats at half that 
distance. In the case of part 5, in the experiments of 1921, the in¬ 
fection recorded on June 30 consisted of a single plant, which was 
removed when first observed. As there was practically no possibility 
