INJURIOUS TO CUCUMBER, SQUASH AND MELON 111 



larvit? work their way down aloiiLi; the stem or under the vines 

 or fruit where they He on the ground. They burrow into the 

 tissue, causing more injury in this stage than is usually thought. 

 Squash vines have been observed practically killed in July and 

 early August from the attacks of the grubs. The stem just 

 below the ground is completely riddled by their burrows. The 

 larva becomes mature in about a month. It is then about -^ 

 inch in length and very slender; the color is white with the 

 head, thoracic and anal plates brown (Fig. 69). When mature, 

 the larva constructs an earthen cell a few inches below the sur- 

 face within which it soon transforms to a nearly white pupa. 

 The pupal stage lasts a 

 week or more. The 

 beetles begin to emerge 

 the last of August or in t.' ^ a. • j v u .1 i '^ 



1 • 1 riG. G9. — iStriped cucumber beetle, larva 



beptember m the more (X7|). 



northern part of the 



insect's range and after feeding for some time on howers, 

 such as goldenrod and asters, go into hibernation with the 

 occurrence of heavy frost. Late in the season the beetles 

 sometimes injure melons by eating holes in the rind and have 

 been known to eat holes in bean pods. In the North there is 

 only one generation annually ; in the South it is thought that 

 the insect is double-brooded. 



The beetles also serve as carriers for a serious disease of 

 cucurbits known as bacterial wilt. They not only transmit 

 the disease from plant to plant in the summer, but the hiber- 

 nating beetles carry over the wilt bacteria and infect the plants 

 in the spring. 



Control. 



As a rule, attempts to poison the beetles have not been suc- 

 cessful because the insects refuse to eat leaves covered with 

 the poison. In many cases it is practicable to protect the 



