522 
HYMENOPTERA. 
become almost yellow. The greater part of them then sud¬ 
denly leave the trees, either by travelling down the trunks, 
or by falling from the branches to the ground. A few, 
either from weakness or from some other cause, remain on 
the trees, make their cdcoons among the leaves, and rarely 
finish their transformations, ’most of them perishing from 
the internal attacks of ichneumon-grubs. Some creep into 
cracks in fences, and into other crevices ; but most of those 
which reach the ground bury themselves under decayed 
leaves, or among the roots of the grass, and in such secure 
places make their cocoons. The latter are oblong oval 
cases, of tough grayish silk, and measure nearly three tenths 
of an inch in length. In due time the insects change to 
saw-flies, and come out of their cocoons, one end whereof 
separates, like, a lid, to allow of their escape. Although 
some of them are found to finish their transformations in 
August, it is probable that the greater part of them remain 
unchanged in the ground till the following spring. 
No means for the destruction of the caterpillars of the 
fir saw-fly have been tried here, except showering them 
with soapsuds, and with solutions of whale-oil soap, which 
has been found effectual. They may also be shaken off or 
beaten from the trees, early in the morning, when they 
are torpid and easily fall, and may be collected in sheets, 
and be burned or given to swine. For other means to 
check their depredations, the reader may consult" the arti¬ 
cles on the pine and fir saw-flies of Europe, contained in 
Kollar’s “ Treatise.” 
The following account of a kind of saw-fly which at¬ 
tacks the grape-vine is chiefly extracted from my Discourse 
before the Massachusetts Horticultural Society, in 1832, 
where the insect is named Selandria Vitis. The saw-fly 
of the vine is of a jet-black color, except the upper side 
of the thorax, which is red, and the fore legs and under 
side of the other legs, which are pale yellow or whitish. 
The wings are semitransparent, of a smoky color, with 
