Passing on now to the statements of other observers, Huber first noticed the remarkable fact that when beehives are attacked by the death's-head moth the bees close the entrance of their hive with wax and propolis to keep out the marauder. The barricade, which is built immediately behind the gateway, completely stops it up--only a small hole being left large enough to admit a bee, and therefore of course too small to admit the moth. Huber specially states that it was not until the beehives had been _repeatedly_ attacked and robbed by the death's-head moth, that the bees closed the entrance of their hive with wax and propolis. _Pure_ instinct would have induced the bees to provide against the first attack. Huber also observed that a wall built in 1804 against the death's-head hawk-moth was destroyed in 1805. In the latter year there were no death's-head moths, nor were any seen during the following. But in the autumn of 1807 a large number again appeared, and the bees at once protected themselves against their enemies. The bulwark was destroyed again in 1808. Again, Huber (_loc. cit._, tom. ii., p. 280) gives a case of apparent exercise of reason, or power of inference from a particular case to other and general cases. A piece of comb fell down and was fixed in its new position by wax. The bees then strengthened the attachments of all the other combs, clearly because they inferred that they too might be in danger of falling. This is a very remarkable case, and leads Huber to exclaim, 'I admit that I was unable to avoid a feeling of astonishment in the presence of a fact from which the purest reason seemed to shine out.' A closely similar, and therefore corroborative case of an even more remarkable kind is thus narrated in Watson's 'Reasoning Power of Animals' (p. 448):-- Dr. Brown, in his book on the bee, gives another illustration of the reasoning power of bees, observed by a friend of his. A centre comb in a hive, being overburdened with honey, had parted from its fastenings, and was pressing against another comb, so as to prevent the passage of the bees between them. This accident excited great bustle in the colony, and as soon as their proceedings could be observed, it was found that they had constructed two horizontal beams between the two combs, and had removed enough of the honey and wax above them to admit the passage of a bee, while the detached comb had been secured by another beam, and fastened to the window with spare wax. But what was most remarkable was, that, when the comb was thus fixed, they removed the horizontal beams first constructed, as being of no further use. The whole occupation took about ten days.