SAW-FLIES. 515 
yet been able to manufacture into paper; — the herculean 
labors of ants in throwing up their hillocks, or mining their 
galleries, compared wherewith, if the small size of the la- 
borers be taken into account, the efforts of man in his proud- 
est monuments, his pyramids and his catacombs, dwindle 
into insignificance. These are only a few of the objects 
deserving of notice among the insects of this order; many 
others might be mentioned, that would lead us to observe 
with what consummate skill these little creatures have been 
fashioned, and how richly they have been endowed with 
instincts that never fail them in providing for their own 
welfare, and that of their future progeny. 
Comparatively speaking, there are not many of the Hy- 
menoptera which are actually or seriously injurious to vege- 
tation. Those which I propose now to describe are not 
provided with venomous stings, and, consequently, are to 
be included among the Piercers. 
Such are the saw-flies (Tenthredinidje), insects that 
are found on the leaves of plants, and live almost entirely 
on vegetable food. They are the least active of the Hvmen- 
optera, are sluggish in their habits, fly heavily and but little, 
and do not attempt to escape when touched. Most of them 
are rather short and somewhat flattened. They have a 
broad head, which, seen from above, appears transversely 
square. The hind body is not narrowed to a point where 
it joins the thorax, but is as broad as the latter, and is closely 
united to it. The antennae are generally short ; but they 
vary much in form ; in many species they are thread-like 
and slightly tapering; in some, thickened or knobbed at 
the end ; more rarely, they end suddenly with a few very 
small joints, much more slender than the rest; they are 
feathered in some males, and notched in the other sex ; and 
sometimes they are forked, or divided into long branches. 
Their wings cross and overlap each other, and cover the 
back horizontally when closed. But the most striking pe- 
culiarity of these insects consists in the double saws where- 
