M. Lichtenstein told us that this larva, which when entire must have been rather more than an inch long, was that of the mullein moth (_Cucullia verbasci_).
It was not full grown, and as there were no mullein plants within some two feet of the nest and this caterpillar will not leave the plant on which it feeds unless compelled, it would seem as if the spider must have gone afield in order to capture it. It is possible, nevertheless, that the caterpillar may have fallen within reach of the spider when blown off the mullein leaves by the wind.
I have, unfortunately, but few details to give of the nocturnal habits of the trap-door spiders. It would appear, however, that they are more active by night than by day, and that it is more common to find their doors ajar at night, with the spiders posted on the look-out at the narrow opening. This is borne out by my observations on captive spiders, to which I shall allude shortly.
When at Hyères on the 11th of May, 1873, the evening being very warm and a bright moon shining, I went at 8:30 P.M. with my father and sister to see what the spiders would be doing on a hedge bank where we had previously marked five cork and eight wafer nests. The moonlight did not fall upon this spot, but I was provided with a lantern, and by its light the nests at first appeared to be tightly closed, but we soon perceived first one and then another with the door slightly raised, ready to close on the smallest alarm, whether from a footfall or from the flickering of the lamp. When the light of the lantern was steady it did not appear to frighten the spiders in the least, even when brought to within a few inches of the door,[148] and this enabled me to watch them very closely. On either side of the raised door of one of the wafer nests I could see the feet of the spider projecting, and just at that moment I caught sight of a beetle close at hand, feeding on the topmost spray of some small plant below. Using every precaution, I contrived to gather the spray without shaking off the beetle, and gradually pushed it nearer and nearer to the nest. When it almost touched the lip of the nest the door flew open, and the spider snatched at the beetle and dragged it down below.