CIRCULAR 2 3 7, U. S. DEPARTMENT OF AGRICULTURE 



seldom attacked. Among the shade trees, it is especially fond of 

 linden, chestnut, horsechestnut, sassafras, and elm. Buttonwood, 

 willow, birch, Lombardy poplar, Norway maple, and certain varieties 

 of oak are occasionally attacked. The beetle rarely feeds on the 

 foliage of most maples, ash, magnolia, mulberry, sweetgum, tupelo 

 (sour gum), tuliptree, hackberry, and beech. As a rule conifers are 



untouched, although 

 occasionally the needles 

 of larch and of bald 

 cypress are injured. 



NATURE OF THE 

 INJURY 



The Japanese beetle 

 has mouth parts 

 adapted for chewing. 

 In general it consumes 

 the tissue between the 

 veins of the leaves and 

 also eats portions of 

 the blossoms and of the 

 fruit. The leaves are 

 skeletonized (figs. 2 

 and 3) and then turn 

 brown and fall. The 

 beetle prefers to feed 

 on portions of the plant 

 exposed to the direct 

 rays of the sun. It 

 usually begins on the 

 upper and outer por- 

 tions and works down- 

 ward and inward (figs. 

 4 and 5). When the 

 infestation is severe, 

 even large trees may be 

 completely defoliated 

 within a few days. On 

 fruit trees a partial 

 second crop of leaves 

 may be produced after 

 the beetle has ceased 

 feeding. This increases 

 the likelihood of winter injury to the twigs, and the tree usually 

 bears no fruit the following year. Kepeated annual defoliation of 

 trees weakens them and ultimately may cause their death. 



Of the susceptible fruits, those that ripen early in the summer 

 are most subject to attack. Very little feeding — only a few punc- 

 tures in the skin — is sufficient to destroy the market value of the 

 fruit, but at times beetles gather on ripening apples and peaches in 



Figure 



-Injury by the Japanese beetle to the foliage 

 of apple. 



