HOW TO KNOW A FERTILE QUEEN FROM AN UNFERTILE ONE
One who has any considerable experience in queen-rearing has no trouble in distinguishing a fertile queen from one that is unfertile. In twelve hours after a queen has mated there is a perceptible increase in her size. Not only is her abdomen larger around, but it is also longer. These conditions are noticeable in the early part of the season, but at the last of September and during the month of October some other way of judging and knowing whether or not a queen has been fertilized must be adopted. While queens that are fertilized early in the season will at once make preparations to deposit eggs, the late fertilized queens do not. That is, the late fertilized queens will not as quickly increase in size after becoming fertile, as they do earlier in the season. Now to decide positively that a queen is fertile I have tested the matter in this way: About half a pint of bees are taken from a colony having an unfertile queen and allowed to run in the hive of the fertile one.
If the queen in the latter hive proves to be fertile, the strange bees will not molest her; if unfertile, the bees introduced may at once ball and eventually destroy her. This is a simple and quick way to test the matter, and applies only to nucleus colonies, though it may be practiced more or less successfully in full colonies.
Another way to decide whether or not a queen is fertile is to feed honey for a day or so. If fertile she will deposit a few eggs, and lay while the feeding is continued.