Oxalic Acid Dribble is a mite control method that uses Api-Bioxal mixed with sugar syrup. It kills mites that are riding on adult bees (usually called "phoretic mites"). It is usually applied using a large syringe to dribble the mixture onto the bees that are clustered between the frames. 

The bees are not harmed by physical contact with the oxalic acid syrup, but they do wind up consuming a small amount of the OA syrup, which can slightly reduce the lifespans of individual bees, especially if it is applied repeatedly. For this reason, oxalic acid dribble is usually done in a single treatment. This is particularly important in winter when individual bees must stay alive for months longer than a typical summer bee. Luckily, since colonies in winter are usually broodless, a single treatment is usually enough to control mites. The method can be used for any number of hive boxes, since you apply the dose in the bottom box and simply stop when you have applied the full treatment amount, no matter which box you’re on.

Equipment needed to do an oxalic dribble

The equipment needed for mixing and applying the treatment is modest and inexpensive: a gram scale, dedicated glass or plastic containers to mix the oxalic acid and sugar syrup, a plastic or wood stirrer, and a 60 cc plastic syringe to do the dribbling in controlled and measured amounts. You can assemble the mixing items on your own from household items and add our oxalic acid dribble kit which comes with everything else you need: the oxalic acid, the syringe, and the personal protective gear. Some beekeepers ditch the syringe and prefer the convenience of another measuring tool, like our EZ-Dribbler bottle

The required personal protective gear includes a particulate mask, eye protection to protect your eyes from any splashes while mixing and applying the solution, and gloves to protect your skin.

We've done the math!

First, make up your 1:1 sugar syrup with half hot tap water and half white granulated sugar. This can be by weight or volume. The exact recipe for syrup isn't important; the important detail is the proportion of Api-Bioxal to syrup because it gives you the desired strength of Api-Bioxal in the batch.



(Oxalic Acid)

Warm 1:1 sugar syrup
20 Hives 35 grams (one 35g packet) 1 liter (approx. 4-1/4 cups)
10 Hives 17.5 grams (½ of a 35g packet) 1/2 liter (approx. 2-1/8 cups)
5 Hives 8.75 grams 8.75 grams (¼ of a 35g packet) 1/4 liter (approx. 1 cup)

Even if you only need enough for a couple of hives, make the 5-hive recipe and discard the surplus. It's hard to accurately mix tiny quantities.

How to mix the oxalic acid solution

You will need a scale that measures in grams to measure the oxalic acid, unless you're using the whole packet. Oxalic crystals clump up and do not measure well by volume, so a scale accurate to 1 gram is essential. Wear goggles and gloves when mixing, and don't touch your eyes or mucous membranes. Have plenty of water available to quickly rinse yourself in case of mishaps. 

Mix the oxalic acid with hot 1:1 sugar syrup (see table) in a glass or plastic container with a plastic (not metal) lid. Important: Mix until the crystals of oxalic acid are dissolved. Close the container tightly and add a label: Caution, Irritant, 2.5% Oxalic Acid. Never place the mixed syrup in repurposed food containers, especially drink bottles where it might be mistaken for a beverage. Unused mixture can be stored refrigerated for a few days. Discard if it turns tan. Dispose of it by diluting it with a large volume of water and pouring it down the drain. 

When working with oxalic acid, always have a source of water available to rinse any accidental contact with skin or eyes. Take a couple of gallons of fresh water to the bee yard with you when you go out to do the treatment.

How To apply the oxalic acid and sugar syrup mixture

Always wear your safety equipment (eye protection, particulate mask, gloves) when working with the mixture.

Winter oxalic acid dribbles can be done in temperatures as low as the low 40s Fahrenheit, when the bees will likely remain clustered during the few minutes the hive is open. OA dribbling can successfully be done by one person alone, though it may be easier if you have a helper, since one person can do the box-opening part and the other can do the actual dribbling. The helper should also be wearing eye protection, a mask, and gloves.

To begin, draw 50 cc (50 mL) (this is the maximum that can be used in a single colony) of the Api-Bioxal/syrup mixture into your syringe and set it aside.

It's good to wear a veil and have a lit smoker nearby, though the smoker may not be necessary. Remove the telescoping cover, but not the inner cover. Then use your hive tool to break any propolis seals between the boxes.

Tilt up the top box and look underneath it to see if there are bees in it. (See below for how to safely tilt up a box.) If you have more than two boxes on the hive, move the tipped-up box to the side, cover it, and continue to work your way downward. Repeat until you have tilted up the next-to-lowest box. When you have the bees in the lowest box exposed, you’re ready to begin the treatment. No need to remove the next-to-lowest box, just keep it tilted up while you treat the box below.

Once you've exposed the lowest box containing bees, use the syringe to dribble 5 cc (or 5 mL) of the Api-Bioxal/syrup mixture over the bees in each of the seams (spaces) between the frames. Do not apply the mixture to any empty seams where there are only a few, or no, bees. Try to get exactly the right amount per seam. When you've done the first box, set the tilted box back down and begin dribbly doses of OA syrup onto any seams with bees in that box. Repeat with any additional box(es) that have bees. Do not exceed a total of 50 cc (mL) per hive, and simply stop whenever you run out of syrup or run out of seams of bees to dribble it on. Then reassemble your hive and close it back up.

If you have a screened bottom board on the hive and can monitor te mite drop on a sticky board, expect to see the largest drop beginning in about 24 hours from the treatment. You may be startled (and maybe gratified) to see how many mites were removed from your wintering colony as a result of treatment. Those are mites that would have jump-started an early mite build-up in the spring.

How to safely tilt a box up

Tilting up a box to look under it without taking it off the hive is one of those bee-handling skills that takes a bit of moxie to do with confidence. But it is an extremely useful skill, and well worth learning to do. Here's how it works:

Use your hive tool to break the propolis seals all around the perimeter of the box you want to tilt. Stand directly behind the hive and with your hands on the sides of the box, tilt the back end up while simultaneously pulling it towards you about 3 or 4 inches. Pulling it towards you will prevent the box from sliding off the front end as you raise it high enough to look underneath (or in this case, to apply the oxalic acid mixture).

When you're ready to set the box down, don't just slide it forward. Instead, pick it up, get it level and set it down vertically. Otherwise, you risk decapitating a lot of bees along the front edge.

Practice this skill, because you can often gather enough information about what's going on in a box just by looking at it from both above and below, and avoid having to pull frames to inspect them. It's especially useful during swarm season when you want to check for queen cells without having to pull frames. You can check a dozen hives for swarm cells by tipping the boxes up in the time it would take to check just a few of them if you were pulling all the brood frames, one by one.