150 
WISCONSIN HORTICULTURE 
June, 1918 
than the dust sprays due to the 
fact that the latter were more 
easily washed off by the heavy dews 
and rains. Tobacco dust and lime 
seemed to have practically no effect 
upon the cabbage worms. 
Common laundry soap used with 
the liquid sprays at the rate of one 
pound or more to fifty gallons gave 
far better results than where either 
molasses alone or molasses and lime 
were used, due to the more even dis- 
tribution of the poison in the case 
of the iormer. 
From one to two applications of 
spray are generally used to com- 
bat the cabbage worm. Ordinarily 
one application made a week or ten 
days after the butterflies appear in 
large numbers in July and another 
in August will give satisfactory 
control. 
In order to determine whether 
or not there is any danger of pois- 
oning to the consumer from the 
use of arsenieals, one head from 
each of six sprayed plats and one 
head from the check plat were 
analyzed by the Agricultural 
Chemistry Department of the Uni- 
versity. The plats from which 
these heads were taken had receiv- 
ed five sprayings, the last spray- 
ing having been applied about a 
week before picking. In preparing 
the heads for analysis, only the 
outer leaves were removed as is 
done by the grower, then one more 
layer of leaves was removed to cor- 
respond to those taken off by the 
housewife. 
Conclusions: While Paris green 
gives efficient control the cost is 
too high for economical use. Lead 
arsenate and calcium arsenate at 
the rate of one pound of the pow- 
der or two pounds of the paste to 
fifty gallons, with the addition of 
one pound or more of common 
laundry soap, give efficient control 
and are the most economical to use. 
No trace of arsenic was found 
to be present on sprayed heads 
prepared for cooking even when 
sprayed as late as a week before 
picking. The outer leaves may 
carry enough arsenic to poison 
stock and are therefore dangerous 
to use for that purpose. 
Control of the Striped Cucumber 
Beetle 
University of Illinois Agricul- 
tural Experiment Station, Urbana, 
Illinois, May, 1918. 
Circular No. 220 
By H. D. Brown 
The striped cucumber beetle is 
one of the most familiar garden 
insects, and one of the most de- 
structive, with which vegetable 
growers must contend. The in- 
jury done to cucumber, squash, 
The striped cucumber beetle, enlarged 5 times. 
pumpkins, watermelon, and musk- 
melon vines by this pest is often the 
cause of the failure of these crops. 
Besides the damage which the 
beetle and its larvae do directly to 
the plants, the adult beetles are 
spreaders of a bacterial wilt. 
LIFE HISTORY 
The adult beetle hibernates in 
the fall under rubbish or boards, 
or in the ground. These beetles 
emerge in the spring several weeks 
before the cucurbitous, or vine 
crops appear. During this time 
they feed upon a wide range of 
vegetation, but congregate imme- 
diately upon any vine crop which 
they may find. They feed raven- 
ously for five to ten days on the 
vine crops, regardless of any poison 
which may have been applied to the 
plants. After that they begin to 
pair and refuse to eat any portion 
of a plant protected by insecticides. 
The eggs are laid the latter part 
of June and during July and hatch 
in about ten days. They may be 
laid wherever the beetle is feeding, 
but will not hatch unless deposited 
in a moist place. 
The larvae likewise require mois- 
ture, and will soon perish if forced 
to remain for any length of time 
in contact with an extremely dry 
soil. Consequently they are likely 
to be found at the base of the plant 
along the stem, and upon the fruit 
where moisture is available. They 
are about three-tenths of an inch 
long, white, with dark brown head 
and anal plate. The larvae feed 
for about a month and then pass 
into the pupal or resting stage. 
The adults begin to emerge about 
the first of August and continue 
until the latter part of September. 
Injury 
The greatest injury is done by 
the adult beetles. They may 
either totally destroy the small 
plants soon after they appear above 
the ground, or they may eat sec- 
tions from their bases, so weaken- 
ing the plants that they are easily 
destroyed by winds. Later they 
congregate on the blossoms and 
destroy the pistils and pollen, and 
seriously interfere with the setting 
of the fruit. It is at this stage 
that injury by bacterial wilt is 
usually noticed. 
