138 
WISCONSIN HORTICULTURE 
June, 1919 
THE INSECT PAGE 
Conducted by the Department of Economic Entomology College of 
Agriculture 
The Striped Cucumber Beetle 
( Diabrotica Vittata) 
Life history and habits : As soon 
as cucumbers, squashes, melons 
and other cucurbits are up, the 
ravages of the striped cucumber 
beetle (see cut) will again be no- 
ticed. Indications point towards 
its presence in great numbers this 
The Striped Cucumber Beetle 
(Enlarged 25 timi?) 
year and the fight against this pest 
so hard to control, should be 
started just as soon as plants 
break through the ground. 
The beetle (adult) spends the 
winter in masses of wejeds and 
rubbish, appearing again about 
the Middle of May. From this 
time until cultivated members of 
the cucumber family are up the 
insect feeds on wild cucumber and 
various weeds, meanwhile laying 
quantities of eggs thereon. Eggs 
hatch in from 7 to 10 days, the 
worms (larvae) immediately eat- 
ing the stems of the food plant, 
there well protected from enemies 
to remain and feed until ready to 
transform into the resting (pupal) 
stage. In this stage also the in- 
sects are safe from attack in their 
earthen cells several inches below 
the surface of the ground. It is 
practically impossible to use con- 
trol measures while the beetles are 
feeding and breeding in waste 
places, consequently the thousands 
of eggs laid on weeds developing 
into beetles in some 50 days or 
about the middle of July fly to 
commercial crops to augment the 
over-wintered beetles already 
there. 
By far the greatest feeding 
damage to cucurbits occurs just 
after they have come up. After 
the vines have commenced to run 
the feeding damage by beetles is 
seldom severe and as soon as blos- 
soms appear they feed largely in 
them to the neglect of the leaves. 
It must be remembered, however, 
that more eggs are being laid and 
the larvae although unseen are de- 
stroying the stems and roots of 
the vines (see cut). 
To add to the feeding injury 
caused by the adults and larvae, 
what creates the greatest loss of 
all are the diseases transmitted to 
the vine by the beetles — the mo- 
saic disease and bacterial wilt. 
Thus control of the insects be- 
comes of supreme inportance and 
has been found to be as baffling as 
it is important. 
Control : Cucumbers, melons 
and squashes can be protected 
from damage in small gardens by 
the use of cloth and screen wire 
cages kept over plants from the 
time they come up until they fill 
the cages. So far this is the only 
practicable means of preventing 
damage that has been established. 
A great many substances such 
as lime, tobacco dust, wood ashes, 
sulfur, naphthalene have been rec- 
ommended to repel the beetles, 
and arsenical sprays have been 
used to kill them, all with varying 
success. From three year’s work 
at Madison on control of the cu- 
cumber beetles, in which a large 
number of substances — dusts and 
sprays — have been tested, the fact 
has been forced out that no treat- 
ment experimented with will con- 
showing injury to roots of cucumber l.y 
larvae. 
sistently repel or kill the insects. 
In fact seldom has a dead beetle 
been found on or beneath any 
treated vine. Bordeaux mixture 
4-4-50 combined with arsenate of 
lead 2-50 has proved to be the best 
spray in partially repelling and 
killing the insects and iu delaying 
the appearance of the diseases. 
Therefore this spray is recom- 
mended as the best means of con- 
trol on large vines, yet discovered. 
Dusts have in the main proved to 
be of little temporary value. 
John E. Dudley, Jr. 
