HYMENOPTERA. Mason Wasp.—­In Ceylon as in all other countries, the order of hymenopterous insects arrests us less by the beauty of their forms than the marvels of their sagacity and the achievements of their instinct.  A fossorial wasp of the family of Sphegidoe,[1] which is distinguished by its metallic lustre, enters by the open windows, and disarms irritation at its movements by admiration of the graceful industry with which it stops up the keyholes and similar apertures with clay in order to build in them a cell, into which it thrusts the pupa of some other insect, within whose body it has previously introduced its own eggs; and, enclosing the whole with moistened earth, the young parasite, after undergoing its transformations, gnaws its way into light, and emerges a four-winged fly.[2]

[Footnote 1:  It belongs to the genus Pelopoeus, P.  Spinoloe, St. Fargeau.  The Ampulex compressa, which drags about the larvae of cockroaches into which it has implanted its eggs, belongs to the same family.]

[Footnote 2:  Mr. E. L. Layard has given an interesting account of this Mason wasp in the Annals and Magazine of Nat.  History for May, 1853.

“I have frequently,” he says, “selected one of these flies for observation, and have seen their labours extend over a period of a fortnight or twenty days; sometimes only half a cell was completed in a day, at others as much as two.  I never saw more than twenty cells in one nest, seldom indeed that number, and whence the caterpillars were procured was always to me a mystery.  I have seen thirty or forty brought in of a species which I knew to be very rare in the perfect state, and which I had sought for in vain, although I knew on what plant they fed.

“Then again how are they disabled by the wasp, and yet not injured so as to cause their immediate death?  Die they all do, at least all that I have ever tried to rear, after taking them from the nest.

“The perfected fly never effects its egress from the closed aperture, through which the caterpillars were inserted, and when cells are placed end to end, as they are in many instances, the outward end of each is always selected.  I cannot detect any difference in the thickness in the crust of the cell to cause this uniformity of practice.  It is often as much as half an inch through, of great hardness, and as far as I can see impervious to air and light.  How then does the enclosed fly always select the right end, and with what secretion is it supplied to decompose this mortar?”]

Wasps.—­Of the wasps, one formidable species (Sphex ferruginea of St. Fargeau), which is common to India and most of the eastern islands, is regarded with the utmost dread by the unclad natives, who fly precipitately on finding themselves in the vicinity[1] of its nests, which are of such ample dimensions, that when suspended from a branch, they often measure upwards of six feet in length.[2]