44 
The dependence of the beetle for food upon the bark of the tree 
which it infests has suggested the use of poisons for its destruction, 
and some tests made at the New York Agricultural Experin^ent 
Station show that the ordinary arsenical poisons applied as a spray- 
will destroy it. Arsenate of lead is the best of these for the pur- 
pose, because of its adhesive quality. Trees to be protected should 
be thoroly sprayed at intervals of about a fortnight, beginning 
Fig. -47. Poplar and Willow Borer, 
Cryptor/iynchug lapathi, a.d\i\t. Length, 
about one-fourth inch. 
with the middle of July and continuing thru August. Moder- 
ately infested trees may be saved by cutting out the grubs and cov- 
ering the wound with tar. Badly infested trees should be taken out 
and burned, either during the winter or before July i of the follow- 
ing season. Nursery trees infested by this insect should be un- 
hesitatingly destroyed, since they are far worse than worthless, and 
are the principal means of conveying the species to places not pre- 
viously infested by it. 
The Dogwood Twig-girdler 
{Ohcrea tripiiuctata Swederus) 
Among the insects whose nice and elaborate instincts connected 
with the placing of their eggs are the wonder of entomologists, we 
must class the twig-girdlers, for their careful preliminary opera- 
tions are such as to suggest a knowledge of vegetable physiology 
and a prevision of the possible difficulties in the way of the de- 
velopment of their young certainly quite beyond the powers of 
insect intelligence, and an unsolved puzzle if regarded as a product 
