BULLETIX 352^ U. S. DEPAETMEXT OF AGRICULTUEE, 



life history, and the means for its control. The work herein dis- 

 cussed was conducted at North East, Pa., during the season of 1915. 



FOOD PLANTS. 



In the region covered by the "s^Titers' observations the natural food 

 plant of this insect is the pin, fire, or bird cherry {Prunus pennsyl- 

 vanica). (PL I; PL V, A and B.) "Wild black cherry (P. serotina) 

 and chokecherry (P. virginiana) are entirely immune from attack, 

 even by the beetles. Among cultivated fruits only sour cherry and 

 peach trees are attacked. Even in the sour cherries those varieties, 

 such as the Early Richmond, which have comparatively thhi foHage, 

 are much more seriously injm'ed than the thicker leafed varieties. 

 Sweet cherry and plum, common report to the contrary notwith- 

 standing, are not at all eaten. The beetles have frequently been 

 found on these trees, but never feedmg. Color is lent to the belief 

 that the}' attack plums by the very general prevalence of the shot- 

 hole fmigus on these trees, casual observers taking the holes caused 



by the fungus to be the feedmg marks of 

 the beetles. 



All of the foregoing observations in 

 relation to cultivated trees apply to the 

 adult beetle. On only one occasion were 

 larvse found on anything other than the 

 pin cherry. On August 24 two larvae 

 were fomid on leaves of Early Richmond 

 cherry. One of these had attamed nearly 

 full growth, while the other was still in 

 the first stage. Neither of them Uved to 

 maturity. In the confinenient of cages 

 larvffi of the second and third stages fed 

 sparingly on leaves of cultivated cherry, 

 but first-stage larvsB died without feeding. One lot of 57 newly 

 hatched larvae were fed on peach leaves, but within 6 days aE. were dead. 

 From the records just given it appears that, except in the adult 

 stage, this species is not hkely ever to become of economic importance. 

 The beetles are mentioned in literature as having been taken on 

 various other plants, such as apple and chestnut, but these were 

 probably merely strays, although Davis (1896)^ states definitely that 

 they attacked apple m jMichigan. The apple was, however, entirely 

 immune to attack durmg the present outbreak. 



Lugger (1899) mentioned ''native plum" as a natural food plant as 

 well as the "fire cherry." 



The old idea that G. rufosanguinea Say is a Southern form of cavi- 

 toUis together with an obvious mixing of data has led to the inclusion, 

 in literature, of Ranunculus acris, a buttercup, among the host plants 

 of cavicoUis. G. rufosanguinea is known to breed on wild azalea. 



> Dates in parentheses refer to the Bibliography, p. 25. 



Fig. 1. — Cherry leaf-beetle {Galerucella 

 cavicoUis): Adult beetle. Much en- 

 larged; natural size at right. (Origi- 

 nal.) 



I 



