168 MESSRS. C. HORNE AND F. SMITH ON HYMENOPTERA 
in size and colour, doubtless in consequence of obtaining more or less food in their larva- 
state. Their sting is very sharp; but they do not attack one when disturbed, but 
fly off. : 
RuAYNCHIUM BRUNNEUM, Fabr. 
This insect in its habits resembles its associate R. carnaticum. It uses holes ready 
prepared—although, having seen it emerge from a gnawed hole in a soft post, the hole 
being the work of the insect, I believe it sometimes to work for itself in preparing a 
habitation. Its body is singularly flexible, so that it is almost impossible to hold it, 
when alive, without being stung by it. 
RHYNCHIUM NITIDULUM, Fabr. (Plate XX. figs. 1 & 1 a.) 
This extremely interesting insect constructs cells of exceeding strength, mostly upon 
timber. The clay is very finely worked with water and some kind of gum—not only 
viscid ejection being employed, but also the juices of the ‘‘ Peepul” (cus religiosa), bird- 
lime in fact, and the gum of the Acacia catechu and other trees. Hence there is no 
need of thickness, and we accordingly find the walls of the chambers very thin, whilst 
their tenacity is so great that the portion of the hard wood on which the series of cells 
was fixed I have cut out with a chisel and hammer without in any way injuring the 
structure. One pair of insects does not usually make more than three cells; but it 
must be remembered that they take a much longer time in making them than does the 
rapid rough-working Megachile. 
The food stored consists of caterpillars; and I have not yet succeeded in hatching a 
parasite from one of their nests, which are strong enough to resist all ordinary attacks. 
Until completed, either one or the other of the insects appears to remain at home (fig. 1); 
and hence parasites have no opportunity of effecting an entrance before the cell is closed 
over. The covering, though thin, is very tough, so tough that I doubt the power of a 
parasite to pierce it. In the figure it will be observed that six cells have been built one 
on another, only one being affixed to the door. This one was attached to a smoothly 
plane surface of “Sal wood” (Shorea robusta); so that the cementing gum must have 
possessed great strength to allow me to cut it out with a hammer and chisel, as before 
alluded to. 
These insects build on roof-beams, so that their nests generally escape notice, besides 
which they are far from common. ‘They are externally of a rich brown colour, glisten- 
ing with gum. 
PTEROCHILUS PULCHELLUS, Smith. (Plate XXI. figs. 8, 8a, & 84.) 
This little insect builds its parallel galleries on the nearly smooth surfaces of white- 
washed and other walls. ‘The cells, as shown in the drawing, are above one another, 
lined with a gummy substance and fine si/k(?) The chrysalis resembles that of Pelopeus, 
to which, however, the insect is altogether unlike. The clay must necessarily, from the 
