Supplement to Harvesting Ants and Trap-Door Spiders

by John Traherne Moggridge; Octavius Pickard-Cambridge

Between this date and the end of November when the spider died, eggs were laid on seven distinct occasions—viz., on July 31, August 11, 15, 31 (when I again found the eggs floating in a drop of liquid, having been deposited on the gauze between two and half-past four o'clock in the afternoon); September 9 (23 eggs laid on the earth near the entrance to the nest); September 19 (about 30 eggs on the gauze), and November 4 (about 30 eggs on the gauze).

Thus, between July 13 and November 4, this spider laid nine clusters of eggs, all but one of which were placed on the same part of the gauze cover, above and a little in front of the door, and the total number of eggs deposited cannot have been less than 250. It is difficult to understand why she should have laid these eggs outside the nest, unless indeed she knew them to be sterile, and so treated them as refuse. I can scarcely believe that such a procedure is in accordance with the ordinary habits of these spiders; for, if the eggs and young are habitually exposed, then the perfect concealment of the nest would lose one of its most important uses. When we remember that there are minute hymenopterous insects which lay their eggs within the eggs of the spiders, we can see how important it may be that the entrance to a nest, which is at once nursery and stronghold, should be closed by a well-fitting door, and one which may exclude, not only the larger and more powerful enemies of the full-grown spiders, but also the tiny and almost imperceptible assailants of the eggs and young.

This Californian spider was always careful to eject from the nest the remains of insects with which I had supplied her, and, as she did so deliberately and by day as well as by night, I had frequent opportunities of watching her. Sometimes, if not alarmed by any sudden movement, she would remain for one or two minutes at the mouth of the nest with the door partly raised, and I was glad to seize these opportunities for making some experiments, with a view to learning whether she would prove as sensitive to sound as she did to other vibrations and to the sight of moving objects.

Placing myself so that the partly-opened door screened me from her view, I was able to approach close to the nest without causing her alarm, and to make different sounds and noises at distances varying from three to fourteen inches.

In no case, however, did she pay the slightest attention; and neither shrill and sudden whistling, deep chest and buzzing sounds, an octave of piercing notes struck upon brass bells, my best imitation of the whirring of the fern owl, or finally, the angry hum of a large humble-bee imprisoned in a paper box, and held within three inches of the door of the nest, appeared to produce any kind of effect. This surprised me, I confess, for, though I am aware that no auditory apparatus has as yet been discovered in spiders, I can scarcely believe that they stand at so great a disadvantage as creatures would seem to do which lack the power of hearing.

These experiments must not, however, be taken for more than they are worth; and the results obtained may have been due rather to apathy in the individual spider than to a want of perception in the race generally. In any case they suggest the need of further experiment and observation in this direction.

In October I carried this Californian spider out with me to Mentone, and she lived there and appeared plump and well until the end of the following month, when she suddenly died, having laid one more group of eggs in the interval. On examination, I found a dark brown spot on one side of the abdomen, and this, I think, probably indicates that her death was caused by some insect of the ichneumon family, which had laid its eggs within the spider's body, after having stabbed it at the place indicated by the discolouration.

Not very long before this melancholy event occurred, I had put the spider to some inconvenience in order to secure her portrait from life, to effect which I took her from her nest and placed her in a deep china saucer.

She exhibited the strongest dislike to exposure, and sought to hide herself even under a fold of blotting-paper which lay in the saucer with her. I also noted that she appeared quite incapable of walking up the sides of the saucer, and it would therefore seem that she was destitute of the viscid hairs which enable some spiders to traverse glazed and polished surfaces.