Treating Package Bees with Oxalic Acid: When and How Much

Treating Package Bees with Oxalic Acid: The Best First Treatment a New Colony Can Get

Every spring, thousands of new beekeepers install their first package and then wait months to think about mites. That wait costs colonies. A package arrives with mites on board, and it also arrives in the one condition where a single oxalic acid treatment can reach almost all of them.

The short version

Install the package, let the queen get released and start laying, and once you see eggs or open larvae give one 2-gram-per-box oxalic acid vaporization any time before the first brood is capped. One treatment, a nearly mite-free start.

Packages Come with Mites

A package is shaken from production colonies, and the mites come along on the bees. There is no capped brood in a package, so every one of those mites is phoretic, riding on an adult, exposed. That is exactly what oxalic acid vapor kills. In an established hive most mites are hidden under cappings and it takes six or seven rounds to work through them; in a fresh package, one round can do the whole job.

Timing: Let Her Lay First

You could vaporize the day you install, since there is no brood and the treatment would work. We don't recommend it. The queen is still in her cage, the bees are stressed from shipping, and a package that isn't settled can abscond. A hive full of vapor on day one is not the welcome you want to give them.

Once there is brood in the hive, the bees will not leave. That is your green light. When the queen is released and you see eggs or young larvae, the colony has committed, and you still have a few days before that first brood is capped and gives mites a place to hide. Treat in that window: brood present, nothing capped yet. Larvae are capped about 8–9 days after the egg is laid, so you have roughly a week. Treat after cappings appear and you'll need the repeated schedule from our dosage and schedule guide instead.

The Dose

Two grams for a package in a single deep, the same 2-grams-per-brood-box rule as every other hive. The InstantVap dispenser dials to 2 grams and stays there, so the treatment is ten seconds through the entrance with no lid off and no disturbance to a colony that is just getting established.

Wash It Later

Two to three weeks after treating, run a mite wash with the Easy-Check. A package that got its clean first treatment usually washes near zero, which puts it months ahead of a package that waits until August.

Tools We Use (and Recommend)

InstantVap Oxalic Acid Vaporizer: cordless, fast, and the easiest vaporizer for a new beekeeper to use well. See all InstantVap models. Lorob Bees is the primary US seller, with stateside service and warranty.
Oxalic Acid: EPA-registered EZ-OX.
PPE: a full-face respirator rated for acid vapor, plus gloves.

Caught a swarm instead? Same idea, slightly different timing: Treating a Swarm with Oxalic Acid.

Happy Beekeeping from the Lorob Bees Team

Written by Rob Pollock

Rob keeps bees in Baltimore, Maryland, and owns Lorob Bees. He built and repaired his own corded oxalic acid vaporizers for years before becoming the primary US seller of the InstantVap, and he still picks up the phone when one needs service. Oxalic acid vaporization is the thing he cares most about in beekeeping, because it's the treatment that keeps hives alive without breeding resistant mites. More about Lorob Bees.

Keep reading: Explore all Lorob Bees beekeeping guides — varroa, oxalic acid vaporization, pests and diseases, all in one place.

Recommendations reflect Lorob Bees' field experience and customer feedback. Always read and follow the label of the EPA-registered oxalic acid product you use.