Bee colonies face various challenges, including tiny parasites known as bee mites. These organisms can weaken bees and entire colonies. Understanding their appearance and location is crucial for assessing bee health and identifying infestations. This guide helps distinguish common bee mites and other small entities found in a hive.
Common Bee Mites and Their Appearance
The Varroa mite (Varroa destructor) is a common external parasite. Adult female Varroa mites are reddish-brown, flat, and oval-shaped, resembling a tiny sesame seed or the head of a pin. They typically measure between 1.1 to 1.8 millimeters long and 1.5 to 2 millimeters wide, possessing eight legs that help them cling to their bee hosts. Their flattened bodies allow them to hide effectively between the abdominal segments of adult bees.
In contrast, tracheal mites (Acarapis woodi) are internal parasites, making them impossible to see with the unaided eye. These microscopic mites, measuring less than 0.2 millimeters, live and reproduce within the breathing tubes, or tracheae, of adult honey bees. Their presence is typically inferred through the symptoms they cause, such as bees exhibiting disjointed wings, often called “K-wing,” or crawling behavior outside the hive.
Another group, Tropilaelaps mites (Tropilaelaps clareae/koenigeri), shares similarities with Varroa mites but are generally smaller and more elongated. These reddish-brown mites are approximately 0.7 to 1.0 millimeters long and 0.5 to 0.6 millimeters wide. They are also active and can move rapidly across comb surfaces.
Where to Spot Mites
Varroa mites are often found on adult bees. They often position themselves between the segments of the bee’s abdomen or on the thorax, sometimes even under the wings. Spotting them on a bee indicates an infestation.
Beyond adult bees, Varroa mites also reproduce within capped brood cells, particularly drone brood, which they prefer. Inspecting uncapped drone pupae can reveal the reddish-brown mites on the developing bees. Another common method involves placing a sticky board at the bottom of the hive, which collects mites that fall off the bees, allowing for their detection.
Tracheal mites, being internal, cannot be visually spotted on the exterior of a bee or within the hive structure. They reside exclusively within the bee’s respiratory system, specifically the prothoracic tracheae, and their identification requires microscopic examination of dissected bees.
Mistaking Mites: What Else Could It Be?
Several small items or other organisms might be mistaken for bee mites. Pollen grains, especially those that are dark or reddish, can sometimes be confused with mites due to their size and presence within the hive. However, pollen lacks the distinct shape and movement of mites.
Small specks of dirt, debris, or even bits of propolis within the hive can also resemble mites upon a quick glance. These inert particles will not exhibit any movement, which helps differentiate them from living parasites.
Other small creatures might occasionally appear in a hive environment. For instance, the Braula fly, sometimes called the “bee louse,” is a small, reddish-brown, wingless fly that can be found on bees, but it has six legs and a different body shape compared to an eight-legged mite. Pseudoscorpions, tiny arachnids about the size of a pinhead, also inhabit some hives and might be seen, but they have prominent pincer-like appendages distinct from mites.