of the attacks of insects.
Dodge and Rickett (1948) report that _Corylus_ may be affected by a
leaf-damage from the feeding of leaf-hoppers (_Phepsins ishida_; _P.
tinctorius_), which may involve less than half the leaf or may extend to
the entire leaf. The first leaves to be infested are those next to the
ground, which are affected early in July. Most of the damage ceases by
the first week of August. Control is by spraying with nicotine sulphate
and soap on the undersides of the leaves in late June or early July,
repeating at the end of a week.

Certain nut weevils (_Balaninus spp._) attack the native hazels, but
Slate (1930) reports they do not attack the European filbert (_C.
avellana_). Mr. Slate reports that in Geneva where nuts are carefully
picked up they do not have much of a problem with weevils.

Dr. Crane reports that the Japanese beetle severely damages the filbert.
While the Japanese beetle has not yet become widely established in
Virginia, it undoubtedly will eventually become a problem throughout
this state. The Japanese beetle can be destroyed by using four pounds of
50% wettable DDT or two pounds of actual DDT per 100 gallons. Such
sprays should be applied as the Japanese beetles begin to cause injury,
and usually two applications may be sufficient.

Mr. G. F. Gravatt has reported that his filbert plantings, surrounded on
three sides by woods, are badly attacked by stink bugs that sting the
nuts. DDT as suggested for Japanese beetles may also be used for stink
bugs.

Another serious insect pest on hazelnut is the curculio. Clean
cultivation has been reported as a supplementary measure for curculio
control, as they depend, upon unbroken soil in the fall for their
metamorphosis. Some hybrids are reported as being relatively immune to
the attacks of curculio (Weschcke, 1946). Benezene hexachloride has
shown promise with other plants in curculio control and may have
possibilities on the filbert.

LACK OF HARDINESS. A third limitation has been lack of hardiness in the
case of European varieties. With the European varieties the staminate or
the pistillate flowers or both are likely to be killed by winter
temperatures. In fact, occasional unduly low winter temperatures may
kill the tree tops or even the tree trunks to the ground. The Winkler
variety (_C. americana_) has been reported as more hardy in New York
State than the Barcelona (_C. avellana_) or the Jones hybrids (_C.
americana_ x. _C. avellana_)