We have seen some hints of Spring in recent weeks, but there still are too many freezing nights and the occasional snowy day. If next week shows the promise of warm sunshine, we will begin making our deep hive inspections. Our winter loss rate is about 17% for this past winter.
One of the most important observations we will make, in the early part of spring, will be to determine Hygienic behavior in selected colonies. From the results of this test we will choose the best queens to use as breeders in our queen rearing operation. The test we use is described in Susan Cobey’s protocol for Queen Selection.
Early in the Spring, before a strong honey flow, we obtain a dewar of Liquid Nitrogen. Other tools to have on hand are, a glass beaker, heavy gloves, and a tin can with both ends cut open and filed sharp at one of those ends. We select a frame of capped brood, and brush all the bees off of it. We place that frame on a solid surface, away from the hive, marking the top of the frame over the spot we plan to test. We press the sharp tin can into the brood down to the mid-line of the comb, being sure to choose a section with fewer than 10 open cells. We pour 10 oz of the N2 into the tin can, and allow it to evaporate completely, in about 5 minutes. A 3 inch diameter tin can will cover about 160 cells. We return the frame with the section of frozen brood, back to the hive. After 24 and 48 hours we recheck that same frame, which has been marked for identification. We count and record the number of remaining capped cells in the frozen section. A Hygienic colony will have no capped cells in that section.