INSECT PESTS OF OHIO SHADE AND FOREST TREES 233 



mines probably are constructed before the larva reaches maturity. 

 The writer has observed nearly full-grown larvae in the act of con- 

 structing new mines, eating through the upper surface of the leaf 

 as a starting point. 



Pupation occurs within the mine. Differing from most pupae, 

 that of this species is very active, easily shifting its position to 

 various parts of the mine. This moving about is greatly facilitated 

 because of the spinelike protuberances with which the sides of the 

 body are armed. 



Almost all the beetles have emerged from the mines by August 

 1, and a general migration occurs, the insects scattering far and 

 wide to new fields. After this short period of wandering, they 

 deposit the second lot of eggs of the season, and the resulting beetles 

 appear in early fall and constitute the over-wintering stage. Thus 

 it will be observed that there are two full broods per season. 



Nature of work. — On black locust this pest is destructive in 

 both adult and larval stages, but in the main, only the adults are 

 destructive to other hosts. In other words, black locust is the most 

 common plant recorded in which the larvae mine the leaves, though 

 the larvae have been recorded (15) from false indigo {Amorpha 

 fruticosa) and from soybean. The adult beetles are foliage feeders, 

 eating irregular holes, and when in sufficient numbers, almost 

 defoliate the trees. Only a partial destruction of the leaf area, 

 however, is sufficient to cause the death of the entire leaf structure, 

 since the unconsumed parts adjoining the mutilations die and turn 

 brown. 



In mining the leaves of the black locust, the young larva, after 

 eating through the leaf surface, proceeds to feed on the inner leaf 

 substances, leaving intact the upper and lower surfaces. Rarely 

 are mines found larger in area than a dime. More than one mine 

 may occur in a single leaflet, but one large mine usually is sufficient 

 to cause its death and browning. In instances of severe attacks 

 the combined feeding of larvae and adults may kill the foliage of 

 the entire tree twice in a single season, once in July and again in 

 September. Thus, during some seasons in southern Ohio whole 

 areas of black locust may be browned and appear as if fire-swept. 

 Because of this fact areas of black locust may be detected for miles 

 distant because of their contrast to the surrounding green trees of 

 other species. The year of 1912 will be long remembered in south- 

 ern Ohio because of this connection, as will also the seasons of 1904 

 and 1905. In 1907 the locust leaf beetle was reported as being 

 unusually destructive in parts of Pennsylvania, and in 1911 and 1912 

 locust ti'ees in some areas of Long Island were very severely injured. 



