The Varroa Mite

The Varroa mite is a parasite originating in Southeast Asia. It has migrated throughout the world because of the unrestricted movement of honeybees and humans.

Mite Nymph

Female mites lay eggs in the cells of older larvae. Mite nymphs (baby mites) feed upon larval blood. Heavy infestation of mites results in several mites feeding off each larva. The larvae lose weight and eventually die.

Adult Mite

Adult mites attach to adult bees. They feed upon them, weakening the bees. Over time mite infestation weakens a hive and could possibly kill it, especially if the infestation occurs unnoticed in winter.

Treatment

Varroa mites can be detected by placing a sticky board (white sheet) on the bottom board. Cover the sticky board with mesh. When the mites fall off the bees onto the sticky board, they cannot re-attach because the mesh prevents their jumping back onto the bees. Varroa mites cannot be completely eliminated, but they can be controlled.

When to Treat?

Varroa mites in a hive are assessed with a population sample of about 1% of the hive's population. During the beekeeping season a hive's population fluctuates. In the spring, a hive usually has a small population of about 15,000 bees; a sample size of about 150 bees should be taken. In the late summer a hive's population can balloon to 60,000 to 80,000 bees; therefore, a sample size of 150 bees should be multiplied by 600.

Note: If brood rearing is underway,such as in late spring and summer, multiple the total number of mites found by 600, because only 15% of mites reside on adult bees. The other 85% of varroa mites are in the honeycomb cells procreating on honeybee brood.

The mites detected from the sample should be multiplied by 100 or 600 to represent the total population of a colony. 150 x 100 = 15,000 or 150x 600 = 60,000.

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