For instance, I had all the bees of a good swarm leave the hive in March; after flying a time, they united with another good stock, making double the usual number of bees at this season; enough to keep the brood sufficiently warm at any time; if other stocks with half or a quarter of the number could. By the middle of June, the bees were much reduced, and had not cast a swarm. It was examined, and the brood was found badly diseased. My best and most populous stocks, in spring, are just as liable, and I might add more so, than smaller or weaker families. I have had two large swarms unite, and were hived together, that were diseased the next autumn. These cases prove strongly, if not conclusively, that animal heat is not the only requisite. The fact that when I had pruned out all affected comb from a diseased stock, and left honey in the top and outside pieces, and the bees constructed new for breeding, and the brood in such were invariably affected, though only a few at first, and increasing as the combs were extended; led me to suppose that it was a contagious disease, and the virus was contained in the honey. Some of it had been left in these stocks, and very probably the bees had fed it to the brood. To test this principle still further, I drove all the bees from such diseased stocks, strained the honey, and fed it to several young healthy swarms soon after being hived. When examined a few weeks after, every one, without an exception, had caught the contagion.
Here then is a clue to the cause of this disease spreading, whether we have its origin or not. We will now see if we can trace it through, if there is any consistency in its transfer from one stock to another.
Suppose one stock has caught the infection, but a small portion of the brood is dead. In the heat of the hive, it soon becomes putrid; other cells adjoining with larvæ of the right age are soon in the same condition. All the breeding combs in the hive become one putrid mass, with an exception, perhaps, of one in ten, twenty or a hundred, that may perfect a bee. Thus the increase of bees is not enough to replace the old ones that are continually dying off. It is plain, therefore, that this stock _must_ soon dwindle down to a very small family. Now let a scarcity of honey occur in the fields, this poor stock cannot be properly guarded, and is easily plundered of its contents by the others. Honey is taken that is in close proximity to dead bodies, corrupting by thousands, creating a pestilential vapor, of which it has probably absorbed a portion. The seeds of destruction are by this means carried into healthy stocks. In a short time, these in turn fall victims to the scourge; and soon dwindle away, when some other strong stock is able to carry off _their_ stores; and only stop, perhaps, at the last stock! The moth is ever ready with her burden of eggs, which she now without hindrance deposits directly on the combs. In a short time the worms finish up the whole business, and are judged guilty of the whole charge; merely because they are found carrying out effects that speedily follow such causes.