How can I determine if bees have mites? - briefly
Examine brood cells for deformed wings and dark, greasy spots that signal mite infestation. Perform a sugar‑shake test or microscopic inspection of adult bees, counting the fallen parasites such as «Varroa destructor» to confirm presence.
How can I determine if bees have mites? - in detail
Detecting mite infestations in honey‑bee colonies requires systematic observation and quantitative sampling.
A quick visual assessment begins with examining adult workers for crawling mites on the thorax and abdomen. Gently shaking a sample of 300–500 bees over a white surface reveals mites that fall off. Counting the fallen mites and dividing by the number of bees provides a preliminary infestation rate.
A more precise estimate utilizes the sugar‑roll method. Place 300 bees in a jar, add powdered sugar, and roll for one minute. The sugar dislodges mites, which are then filtered through a fine mesh and counted. A result of 3 % or higher indicates a significant problem.
The alcohol‑wash technique offers comparable accuracy. Submerge 300 bees in 70 % ethanol, agitate for one minute, and filter the liquid. Mites settle on the filter and are counted. This method destroys the sample but yields reliable data for treatment decisions.
Brood inspection targets reproducing mites. Open several capped cells in the brood nest and examine the pupae and surrounding comb. Presence of mites on the pupae or in the cell walls confirms colony‑level reproduction.
Sticky boards provide continuous monitoring of falling mites. Place a board coated with a sticky substance beneath the bottom board for 24–48 hours. Count the mites captured; a weekly average exceeding 10 mites per board signals an escalating infestation.
Laboratory diagnostics, such as polymerase chain reaction (PCR), detect varroa DNA in bee samples with high sensitivity. While costly, PCR confirms low‑level infections before visual signs appear.
Sampling frequency should align with seasonal dynamics. Conduct assessments every 4–6 weeks during spring and summer, when mite reproduction peaks, and at least twice annually during winter.
Thresholds for intervention vary by region, but most guidelines recommend treatment when the sugar‑roll or alcohol‑wash count reaches 3 % or when sticky‑board counts exceed 10 mites per day. Early detection and consistent monitoring reduce colony loss and maintain honey‑bee health.