Bees have so many issues to deal with.

There's a lack of nectar and pollen sources as wildflower populations diminish. Pesticides like neonictinoids are harming their nervous systems (read about that here). There's unexplained colony collapse disorder.

And then there are varroa mites.

So many invasive species have caused catastrophic effects on different parts of the environment, and varroa mites are an invasive parasite that many beekeepers are dealing with. The varroa bee mite (Varroa jacobsoni) was first discovered in the early 1900s but was not found in the United States until 1987, when it was detected in Florida. Because it is a relatively new parasite to European honeybees, originating on Apis cerana instead of Apis mellifera, European honeybees do not have as much resistance to them. Some beekeepers are looking at keeping Russian honeybees which have a higher tolerance for varroa mites than other subspecies.

Mites travel from hive to hive on adult bees. When a drone is out looking to mate or a worker bee is out foraging, the mite can drop off onto a plant and then climb on to the next bee that stops there or it can transfer from bee to bee while they are near each other. Robber bees can also transport varroa mites while stealing food from smaller hives.

Varroa mites are deadly to honeybees. They are an external parasite similar to a tick to humans --- imagine a tick the size of your first on your chest.

Varroa mites have eight legs and are reddish-brown with oval-shaped bodies that are large enough to see without a magnifying glass.

Photo of bees with varroa mites

The mites affect bees in multiple ways.

First, mites develop on drone brood in particular. A female will go into the brood cell before it is capped, and then when it is capped, she will begin to feed on the larva. At the same time, she lays eggs which also hatch, develop and mate while feeding on the larva. This larva will develop into an unhealthy adult with a weakened immune system or even with deformities.

Varroa mites also parasitize adult bees, breaking through the bee exoskeleton and surviving off of the bee's blood. This will weaken the immune system and may kill the bee. Even if the mite dies or leaves the bee, it will leave behind a hole in the exoskeleton that the bee cannot heal, therefore ensuring the bee's eventual death.

Varroa mites also carry diseases that can kill bees.

When caught early, varroa mites can be treated in a variety of ways, but like many invasive species, they are difficult to completely get rid of. The best way to control invasive species is to prevent them from spreading in the first place!

Read other blogs in the What's Happening in the Hive? series:
How a queen develops
Festooning bees
Drying down honey
Why aren't there any drones?

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