2.2.2. Where to find mites

Live adult mites, nymphs and eggs are most easily found in capped brood cells of bee colonies in which adult female mites are reproducing. In A. cerana colonies this is restricted to drone cells, but in A. mellifera colonies it may be either drone or worker cells. After removing the wax cappings and bee brood, the presence of white faecal deposits on cell walls (Fig. 3) is a sure indicator of the presence of reproducing females. Collecting mites from brood cells with offspring also provides evidence that these mites indeed reproduce on the bee species they have been collected from, as mites sometimes drift to and from colonies of foreign species on which they are unable to reproduce (Anderson and Trueman, 2000; Koeniger et al., 2002), which might confuse the host-specificity attributed to them. Only live adult female varroa can be collected from broodless bee colonies. These are generally found on the bodies or in body cavities of worker bees.

Fig. 3. In this section of a cell (the bottom is on the right side), the pearly white faeces deposit is visible on the upper and back walls. Mature and immature varroa mites are also visible. Photo: Swiss Bee Research Institute.

 Figure 3