Harvesting Ants and Trap-Door Spiders / Notes and Observations on Their Habits and Dwellings

by John Traherne Moggridge

[54] Nests belonging to the type A, are represented in Plates VII., p. 88, and VIII., p. 94.

The West Indian nests are of a much tougher and coarser texture than those which I have seen in Europe, and vary somewhat in the shape of their tube, which is curved or straight, and sometimes has near its lower extremity a short spur-shaped enlargement, giving to the whole a ludicrous resemblance to a stocking, of which this spur is the heel.

Mr. Gosse,[55] in his Naturalist's Sojourn in Jamaica, has given an admirable description of one of these single door wafer nests, the work of Cteniza nidulans, which I cannot do better than quote:—

[55] Gosse (P. H.), Naturalist's Sojourn in Jamaica (1851), p. 115-118. See also for another description of the same nest Latreille's Vues Générales sur les Araneides, in the Nouv. Ann. du Muséum (Paris, 1832), tom. i. p. 73-4.

The nest is "cylindrical, or nearly so, from four to ten inches deep, and about one inch in diameter; the bottom is rounded; and the top, which is at the surface of the soil, is closed very accurately with a circular lid. They are not all equally finished, some being much more compact, and having the lid more closely fitted than others. Some have irregular bulgings, and ragged laminated offsets on the outer surface; but all are smooth and silky on the inside.... The mouth of the tube, and the parts near it, are very strong; the walls here often having a thickness of from one-eighth to one-fourth of an inch; but the lower parts are much thinner. The lid is continuous with the tube for about a third of its circumference, and this part may be called the hinge, though it presents no structure peculiar to itself; it is simply bent at a right angle, as is manifest, if a nest be cut longitudinally through with scissors, the incision passing through the midst of the lid. The mode of construction, I judge, from examination of many nests, to be this. The spider digs a cylindrical hole in the moist earth, with her jointed fangs or mandibles, carrying out the fragments as they are dislodged. When the excavation has proceeded a little way, she begins to spin the lining which forms the dwelling. I conclude thus, because nests are occasionally found a few inches in length, with the lid and upper part perfect, but without any bottom, these being evidently in the course of formation. I suppose that she weaves her silk at first in unconnected patches, against the earthy sides, perhaps where the mould is liable to fall in; and thus I account for the loose rough laminæ of silk that are always found projecting from the outer surface. These are overlaid with other patches more and more extensive, until the whole interior walls are covered; after which the silk is spun evenly and continuously all round the interior, in successive layers of very dense texture, though thin. Under the microscope, with a power of 220 diameters, these layers are resolved into threads laid across each other and intertwined in a very irregular manner; some are simple, varying from ¹/₇₀₀₀ to ¹/₂₀₀₀ of an inch in diameter, and others are compound, several threads, in one part separate, being united into one of greater thickness which cannot then be resolved.... The mouth of the tube is commonly dilated a little, so as to form a slightly recurved brim or lip; and the lid is sometimes a little convex internally, so as to fall more accurately into the mouth and close it.

"The thickening of the hinge by additional layers is, I think, accidental only, as, out of the many specimens that I have examined, only one or two had such a structure. In the neatest examples, the lid is of equal thickness throughout its extent, agreeing also with the walls for the first few inches of their depth."

Mr. Gosse says that he possesses one specimen of peculiar compactness, which differs from all the others that he has examined in having "a row of minute holes, such as might be made by a very fine needle, pierced around the free edge of the lid, and a double row of similar ones just within the margin of the tube. There are about fifteen or sixteen punctures in each series, and they penetrate through the whole substance, the light being clearly seen through each hole. I do not think, as I have somewhere seen suggested, that they are intended to afford a hold for the spider's claws when she would keep her door shut against the efforts of an enemy, for what would be the use of having them in the tube close to the lid, so close that not the eighth of an inch intervenes between the surface of the lid and that of the tube, when the former is tightly closed? I would suggest whether they may not be air-holes, for so tight is the fitting of the lid, and so compact the texture of the material, that I should suppose the interior would be impermeable to air but for this contrivance."[56] "The spider that inhabits this nest is black, with the thorax of an exceedingly lustrous polish, its abdomen is full and round, its legs very short."

[56] I cannot myself think this explanation probable, and should still be inclined to consider these punctures to be the claw marks of the spider, as is the case in some European nests.

Another form of this single door wafer nest is described by Mr. Sells,[57] in which there is a hinge-like thickening of the silk lining of the tube about an inch below the actual hinge of the door, which it is suggested may serve to give additional elasticity. This was not found, however, in all the nests examined, and Mr. Sells conjectures that in newly constructed nests the lid may close sufficiently firmly without this contrivance, and that it is only added in older nests.

[57] Mr. W. Sells. Notes respecting the Nest of Cteniza nidulans, in Trans. Ent. Soc. ii. 207-210.