HYMENOPTERA. 207 
nests she has prepared for them, which are frequently constructed 
with so much art as to excite our wonder and surprise, and some- 
times by depositing her eggs in the body of the larvee and nymphs of 
Insects, on which her progeny are to feed. 
Other larvee of Hymenoptera, also destitute of feet, require more 
elaborated and frequently-renewed supplies of aliment, both vegeta- 
ble and animal. These are reared in common by neuters forming 
communities, of which they have the sole care; their labours and 
mode of life will always continue to excite our admiration and as- 
tonishment. 
Almost all Hymenopterous Insects, in their perfect state, live on 
flowers and are usually most abundant in southern climates. Their 
period of life, from their birth to their ultimate metamorphosis, is 
limited to a year. 
M. Leon Dufour in his Memoire sur l’Anatomie des Scolies— 
Journ. de Phys., Sept. 1828—remarks, that in all the Hymenoptera 
submitted to his scalpel, the tracheze are a degree more perfect than 
those of the other orders of Insects; that instead of being formed by 
cylindrical and elastic vessels, the diameter of which decreases by 
their successive divisions, they present constant dilitations, decided 
vesicles favourable to the greater or less permanence of air, and sus- 
ceptible of extension and diminution, according to the quantity of 
that fluid admitted. On each side of the base of the abdomen may 
be found one of these vesicles; it is large, oval, and of a dead lacte- 
ous-white, giving off here and there vascular tracheze which are dis- 
tributed among the adjacent organs. In penetrating into the thorax 
it is strangulated, dilates again, and insensibly degenerates into a 
tube, the subdivisions of which are lost in the head. Behind these 
two abdominal vesicles, the organ of respiration continues on in two 
filiform tubes, giving off an infinity of ramous branches, and becom- 
ing confluent near the anus. In the Xylocope and Bombi, the an- 
terior superior surface of each of the two great abdominal vesicles is 
furnished with a cylindrical, elastic, greyish body, but adhering 
throughout its length in the Xylocope, and free in the Bombi. M. 
Dufour thinks that this body, which is directed towards the insertion 
of the wing, has some part in the production of the humming noise 
made by these Insects, inasmuch as that sound may continue after the - 
wings have been taken off. 
I will divide this order into two sections. 
The first, or that of the TEREBRANTIA, is characterized by the pre- 
sence of an ovipositor in the females. 
I divide this section into two great families. 
