48 
EASTERN SHADE TREE CONFERENCE 
Tree Preferences of the Beetle. Experience has shown that in 
its choice of food, the Japanese beetle shows a marked preference for 
certain forms of vegetation and more or less avoids, or but rarely attacks 
others. Among shade and ornamental trees, it is especially fond of 
sweet and ornamental cherries, linden, Lombardy poplar, plum, horse- 
chestnut, sassafras, willow, apple, and elm. Where the beetles are 
extremely abundant it frequently happens that all or the greater part of 
the foliage of such trees will be completely riddled and turned a rusty- 
brown tint, suggestive of conditions in late autumn. Other trees, such 
as buttonwood, birch, Norway maple, and certain varieties of oak, 
namely, pin oak, chestnut oak and white oak, are often extensively 
attacked, but rarely so frequently or so severely as those first mentioned. 
Among broadleaved deciduous trees the Japanese beetle either does not 
attack at all, or at most only very rarely, the foliage of such shade trees 
as most maples and poplars, the ash, magnolia, mulberry, sweet gum, 
sour gum, tulip tree, hackberry, and beech. As a rule conifers are un¬ 
touched, but there are occasions when the beetles injure quite severely 
the fresh and tender needles of bald cypress and larch. 
The usual food preferences of the beetle are often modified by local 
conditions to such an extent that a species of tree usually preferred may 
be only incidentally attacked, while a tree which is ordinarily but slightly 
fed upon may be very seriously attacked. Trees in closest proximity 
to favored breeding grounds, such as lawns and golf courses, from which 
beetles are emerging in numbers, are usually attacked first, even though 
they are of the less favored “occasionally attacked” group. The extent 
to which a tree is exposed to sunlight is a very important factor causing 
variation in species susceptibility to beetle attack. Other factors being 
equal, trees standing alone are more liable to attack than the same 
species when in groups. In group plantings, the inner trees being 
shaded and protected, are seldom if ever attacked to any extent, while 
the outer trees, especially those most exposed to sunlight, may be severe¬ 
ly attacked. In the same way, trees in wide thoroughfares exposed to 
sunlight during the middle of the day are more susceptible to attack 
than those on narrow, shaded streets. In general, a shady environment 
is not only less attractive to beetles, but at times may be very repellent. 
Recommendations for Shade Tree Protection. It is not a difficult 
matter to protect most healthy, vigorous shade trees from attack by 
Japanese beetles, provided suitable equipment is available, proper ma¬ 
terials are used, and the work is properly done. Diseased and poorly 
