THE CUCUMBER BEETLE 
BY C. A. SELL 
INTRODUCTORY NOTE. 
During the past summer, Mr. Sell, a graduate student of the University, 
wishing to do some work in Economic Entomology at a time when ho 
course was being given, took up a special problem for investigation. As 
he had but the summer to work, it was suggested that he work out the life 
history, as far as possible, of the cucumber beetle, which is frequently very 
injurious to cucumbers grown in cold frames and to try a treatment for 
the larval stages which was originally suggested by Mr. F. A. Gibbs, a 
market gardener. The remedy, tobacco extract, has been found to be very 
efficient and could even be used in a much smaller proportion than origin- 
ally employed. 
We wish to thank Mr. Gibbs for the use of his plants and for aid given 
during these experiments. 
WILLIAM MOORE, 
Head of Section of Truck Crop and Greenhouse Insects. 
In Minnesota, early cucumbers are raised in cold frames or 
‘‘out-door hot-beds.” Two or three weeks after the glasses are 
permanently laid aside, cucumber beetles begin to gnaw the leaves. 
While they seem to prefer leaves that are young and tender when 
they begin work, they will usually continue to attack a leaf that has 
been injured in preference to a younger, healthy leaf. As the plants 
grow very rapidly and the beetles are usually very numerous., this 
damage can be overlooked. A.bout the middle of June, they begin 
mating and for about two weeks are more destructive to the plants 
than they have been earlier in the season. They are so much in 
evidence and their injury to the plants is so obvious that the 
farmer is tempted to spray or dust the plants with Paris green or 
lead arsenate, which is of very little value at this time. 
But the feast will not last more than two or three weeks, and 
the plants will easily withstand the attack which is not waged at a 
vital part. If the injury becomes too great, air-slaked lime or ashes 
dusted over the plants will tend to drive the beetles away, and will 
probably be of as much value at this time as an arsenical spray. 
The males die first. Soon after the female is fertilized, the male 
