ORDER COLEOPTERA 203 



enter the leaf. If the leaf becomes too dry or the space 

 within it too crowded, the larva will leave its mine and crawl 

 about in search of a place to start a new one. Cutting a slit 

 in the epidermis, it may readily re-enter by eating its way in. 

 The larva when grown leaves the mine and descends an 

 inch or less into soft soil to form a pupal chamber there. It 

 emerges as an adult about two weeks later. In the northern 

 United States there is a single annual brood, but in the 

 latitude of Washington and southward two generations 

 occur. 



Phyllotreta 



The flea beetles of this genus are widely known as pests 

 of cruciferous plants. The adults of the various species 

 feed upon the leaves of our various cultivated cruciferous 

 plants, such as cabbage, radish, turnip as well as upon 

 various wild cresses and weeds. In the larval state some 

 of the species live in the interior of the leaves while others 

 are subterranean in habit and feed on roots. Phyllotreta 

 vittata according to Comstock, Chittenden, Thomas and 

 others, has the latter habit. The grub is described as 

 small and slender and almost entirely white. The pupa is 

 said to be found in a little earthen cell a few inches deep in 

 the soil. Phyllotreta nemorum of Europe and Phyllotreta 

 sinuata of North America, on the other hand, mine in the 

 interior of leaves in the way described by Harris. It is 

 probable that others of our species do likewise. According 

 to Miss Murtfeldt Phyllotreta sinuata breeds chiefly in the 

 leaves of pepper grass (Lepidium spp.) and rock cresses 

 (Arabis spp.). Chittenden (1923) lists P. zimmermanniy 

 P. liebeckei and P. aeneicollis as leaf miners. 



The cucumber flea-beetle, Epitrix cucumeris, is said by 

 Comstock and others to be a further example of a flea-beetle 

 with a mining larva. This is a common pest on cucumber 

 and melon vines. It is also known to attack potato, rasp- 



