44d On an Insect injurious to Fruit Trees. 
and branches of the trees from which they have emerged ; flying 
about, like other moths, only in the night. The sexes, judging 
from those I reared under glass, copulate soon after their ex- 
clusion from the chrysalis; and as the female, as remarked by 
Brahm, is not providéd with any instrument for piercing the 
bark, it is probable that she deposits her eggs on the outside of 
it, the young larva subsequently making their way into the tree. 
» The only work in which [| have found any allusion to the 
ceconomy of this insect, is a German publication, Brahm’s In- 
sekten Kalender. In this it is briefly observed, that the larve 
winter in the trunks of apricot- and almond-trees, upon the sap 
of which they are supposed to live, and to which it is conjec- 
tured they are very injurious. 
With regard to the best mode of destroying these insects, 
when their attacks are injurious, | have nothing better to offer 
than afew imperfect hints. ‘The first and most essential process 
evidently is, to cut away the edges of the cankers where they 
are chiefly found, making the wound smooth, and covering it 
with any composition likely to prevent the moth from depositing 
her eggs there again. One precaution is necessary, to put into 
boiling water, or bury at a considerable depth, the cut out pieces 
of decayed bark containing the larve; whicli, if left near the 
tree, would soon craw! from their holes and remount it; thus de- 
feating the labour of the horticulturist, who, often, from neg- 
lecting a slight additional trouble, loses the benefit of more pain- 
ful exertions. 
Rosell tells us (Insekten Belustigung, 1. iv. 171.) that the 
German gardeners, after collectiig from their cabbages, with 
uuwearied industry, whole baskets full of the destruetive Noctua 
Brassice, bury them in a shallow hole in the earth; thus un- 
wittingly counteracting their objeet in the most effectual way. 
For as this insect naturally undergoes its metamorphosis under 
ground, and many of the larve are full grown, they assume the 
chrysalis form in the hole into which they have been thrown, 
and in a few weeks emerge in the moth state, ready to lay thou- 
sands of eggs for a new brood. 
Where the larve are found to have insinuated themselves ge- 
nerally into the rough bark of old trees, it would probably be 
advisable to adopt Mr. Knight’s judicious recommendation on an- 
other occasion, and scrape off the whole of the lifeless bark, and 
such portions of the alburnum as are injured; a process which, 
there can be no doubt, would be advantageous to the tree in 
other respects pointed out by Mr. Knight. Where projecting 
saw-dust-like masses. show that the larva has attacked even 
smooth-barked trees, the insertion of a blunt pricker into the 
hole would probably, in most cases, suffice to destroy it, and do 
less 
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