518 
II YMENOPTERA. 
coming to their growth, and passing through all their trans- 
formations, within six or seven weeks from their first ap- 
pearance. 
The names of above sixty native species of saw-flies may 
he found in my “ Catalogue of the Insects of Massachu- 
setts."’ Some of these are very interesting in their appear- 
ance and habits in the caterpillar state. In what follows, 
an account will be given of one of the largest species, and 
of some smaller kinds, that have been found very injurious 
to cultivated plants. 
Our largest saw-fly belongs to the genus Cimbex (Plate 
VIII. Fig. 12, Cimbex Ulmi). This name was originally 
given by the Greeks to certain insects resembling bees 
and wasps, but not producing honey. It therefore ap- 
plies very well to some kinds of saw-flies, such as the 
female of this species, which, at first sight, might be mis- 
taken for a hornet. Her head and thorax are shining 
black. Her hind body is oval, and of a steel-blue or deep 
violet color, with three or four oval yellowish spots on each 
side. Her antennae are buff-colored, except at the base, 
where they are dusky ; they are short, and end with an 
egg-shaped knob. Her wings are smoky brown, and semi- 
transparent. Her legs are blue-black, and her feet pale 
yellow. The length of her body varies from three quar- 
ters to seven eighths of an inch, and her wings expand an 
inch and three quarters or more. In the manuscript lec- 
tures of the late Professor Peck, she is called Cimbex Ulmi , 
because she inhabits the elm. The male is the Cimbex 
Americana of Dr. Leach, and differs so much from the 
female, that it might be taken for a different species. His 
body is longer and narrower than that of the female, and 
wants the white spots on the sides; and there is a trans- 
verse, oval hole, filled with a whitish film, behind the tho- 
rax, which is hardly perceptible in the other sex. ' His 
hind legs are very thick; the shins are bowed, and hairy 
within ; and the first joint of his feet ends with a stout 
