Report of Entomologists of Experiment Station. 567 



from Mr. Wm. II. Williams, of Jericho, L. I. Mr. Williams sajs: 

 "This beetle is quite discouraging to the growers of early pickles or 

 cucumbers. Half-grown vines as they begin to produce fruit, die 

 here and there^ and in most pickle iields the vines also appear to be 

 injured as a result of an attack upon the roots. This last evil 

 threatens to ruin the industry. It has moved the western limit of 

 successful pickle growing from the immediate vicinity of Jamaica 

 to Westbury* in twenty-five years." While there are other destruc- 

 tive insects which feed upon the cucumber, including one or two 

 species of cut-worms known to attack the roots, there is, probably, 

 no one species which has been so persistent in its attacks in the 

 locality referred to as the cucumber beetle. This insect may be 

 considered tlien, a regular visitor, although like other insects, its 

 increase is influenced by the weather. Dry seasons are considered 

 more favorable for its growth and development. The two seasons 

 previous to this were unusually dry on Long Island and the beetles 

 were very abundant, but during the past season rain has been more 

 plenty and the beetles less numerous. 



Description and Life History. 



The cucumber beetle is too well known among farmers and 

 gardeners to need a description here, excepting for the fact that 

 there is another beetle of about the same size and general outline 

 which is frequently found in company with it. Judging from our 

 experience, tliis fact often leads to confusion in the minds of many 

 growers as to the identity of the real cucumber beetle. The beetle 

 referred to is commonly known as the twelve-spotted diabrotica, 

 and scientifically as Diahrotica \%jpiinctata. It is not considered 

 an enemy of any importance to cucurbitaneous plants, In its larval 

 form, however, it is known as the Southern corn-root worm, and 

 is a well known and often much-dreaded pest to corn growers. 



Although the beetles resemble each other in general outline, they 

 may be easily distinguished by their markings. As its name indi- 

 cates, the twelve spotted Diabrotica is marked with twelve spots. 

 These are conspicuous black spots on the wing covers. The striped 

 cucumber beetle has three black stripes in place of the spots. Fig. 6 

 represents the striped cucumber beetle greatly enlarged. The head 



* A distance of over 115^ miles. 



