The viruses, and why they are really a mite problem

You cannot treat a bee virus. You treat the mite that spreads it, and that is not a consolation prize, it is the actual control.

Deformed wing virus is the one you will see

Adult bees emerging with crumpled, shrivelled wings that never open, often with shortened abdomens. They cannot fly, they are usually dragged out within a day or two, and finding several in a colony is a serious signal.

Visible deformed wings generally mean the mite load has been high for some time. By the time you are seeing them, this is not an early warning, and a colony showing them in fall is at real risk of not reaching spring.

The mite is the vector and the amplifier

Viruses exist at low levels in most colonies without doing obvious harm. Varroa changes that in two ways: it moves virus directly into the bee's body while feeding, bypassing the defenses an oral route would meet, and it suppresses the bee's immune response.

That is why the relationship is not additive. A colony with mites and virus is in worse condition than the two problems separately would suggest, and it is why mite thresholds are set well below the level where you see obvious mite damage.

What the other names mean

Sacbrood shows as larvae that fail to pupate and turn into fluid-filled sacs, usually scattered, and it commonly clears on its own in a strong colony. Chronic bee paralysis produces trembling, hairless, shiny-looking bees, sometimes in distressing numbers, and often resolves without intervention. Black queen cell virus mainly matters to people raising queens.

These get long entries in the literature and very little of it is actionable. Recognizing them is worth something, mostly so you do not mistake them for something that is.

There is nothing to spray

No approved antiviral exists for honey bees, and anyone selling you one is selling something else. The levers are mite control, requeening with better stock, and keeping the colony strong enough to replace damaged bees.

If you take one thing from this: the treatment window for the mites in late summer is the treatment window for the viruses, and it is the same decision. What you do in August determines what the bees raised in September look like, and those are the bees that have to live until spring.

References