129 
Clear as the proof is thus made of some evident connection 
between the abundance of insects in the field and the injury done 
to the berries, this is rendered still more positive, by a fact already 
alluded to, but not readily shown in this table, viz: that those 
fields in which the injury was the least contained a larger ratio of 
adults than the others, these winged individuals having evidently 
recently entered them from worse infested fields, so that the differ- 
ences in number of bugs between injured and uninjured fields must 
have been decidedly greater before any of the insects of this brood 
got their wings, than when these collections were made. 
Unfortunately my notes are not complete in this particular, but 
of twenty-nine insects from fields but little injured, seventeen were 
adults (fifty-eight per cent.) ; while of two hundred and four collected 
where the damage was serious, only sixty-eight were adults (thirty- 
three per cent). I ought to say in respect to the method of these 
observations, that I was in nearly every case accompanied by the 
owner of the fields, and that the estimate of damage was made by 
him, and entered upon my notes before the plants were searched 
for insects. 
Strong as this evidence may seem, it should have no more than 
its due weight. What we have demonstrated is a decided proba- 
bility of a connection of some sort between the injury to the berries 
and the presence of the plant bugs, and a considerable probability 
that this connection is that of effect and cause; that the injury 
is due, at least in part, to the abstraction of the sap from the berry 
by the bug at a critical time in the development of the fruit. 
Final proof of the amount of the injury due to the work of the 
insect, can only be had by experiment. For instance, two adjoin- 
ing portions of the same field must be treated precisely alike in all 
respects, except that the plant bug shall be kept down in one, and 
allowed free course in the other; when a coinparison of the fields 
will give us exact grounds for a conclusion. 
SUPPOSED POISONOUS EFFECT. 
Before leaving this subject of the injuries to vegetation, it will be 
worth while to advert to one matter of both scientifie and practical 
interest,—that of a supposed poisonous effect upon the plant due to 
the punctures of this insect. 
Dr. Harris says: ‘They principally attack the buds, terminal 
shoots, and most succulent growing parts of these and other herb- 
aceous plants, puncturing them with their beaks, drawing off the 
sap, and, from the effects subsequently visible, apparently poisoning 
the parts attacked. These shortly afterwards withered, turned 
black, and in a few days dried up, or curled, and remained per- 
manently stunted in their growth.” 
Riley remarks: ‘Its puncture seems to have a peculiarly poison- 
ous effect, on which account, from its great numbers, it often 
proves a really formidable foe. It is especially hard on young pear 
