Brood scraping technique against varroa mites

Varroa has become the most important enemy of bees. This mite wreaks havoc in apiaries and it is almost impossible to eradicate it permanently. In recent years, a method of combating the Varroa mite has begun to spread among beekeepers. This is brood scraping, a controversial system of varroa control that has both strong advocates and strong detractors.
In this article, we explain what brood scraping is, how it is done and what are its advantages and disadvantages.

1- What is the brood scraping technique against varroa mites?

The brood scraping technique is a means of controlling the varroa mite which consists in destroying the bees’ brood by scraping the capped cells. This approach is based on a well-known idea of varroa control: acaricide treatments are not very effective when there is a lot of capped brood, because the varroa survives inside closed cells.

Beekeepers who use brood scrapers explain that by removing the brood, the bees clean out these cells, eliminating the varroa mites in them and allowing the active ingredient in the miticide to circulate throughout the cells, thus eliminating many more varroa mites.

The idea is not new. It was used in the early days of varroa mites in Europe, before there were acaricides specifically for beekeeping. However, its use was not widespread and was limited to limited experiments.
It was not until 2014 that the method was revived. It did so thanks to Randy Oliver, an American beekeeper and biologist who was tired of fighting varroa mites by all known means, decided to do something more radical. He had his hives in California, where drought and varroa mites were decimating his bees, and then, in his words, « I thought of something crazy. » His experience is summarized in this text from the publication where he unveiled the method:

« If I removed all the capped brood (and the mites in it) from each hive, all that would remain would be the varroa mites in the phoretic stage [when they attach to an adult bee], which would expose them to [acaricide] treatment. We could have removed the brood combs, but that would not have been practical. However, what would happen if we killed all the sealed brood with an uncapping comb? That would be the same as losing the 12-day-old brood. I figured that this brood was already largely doomed, as it was full of varroa mites, and by removing it, I was giving the hive a fresh start from scratch. »

Oliver’s article was published in January 2015, and while trade publications didn’t pay much attention to it, beekeepers did. In search of a solution to such a serious problem, many professionals began trying the method. And it was in Spain that it was taken most seriously.

Beekeepers in northern Spain – and other regions – have been working with the scratch rearing method since 2015, and so far it seems that the results are encouraging. However, it should be noted that no serious scientific studies have yet been published to prove or disprove the effectiveness of the method.

2 – How is the scratch brood technique done?

Beekeepers who work with scratch brood start with the same three ideas that encouraged Oliver to try this « crazy idea »:

1 – The miticide works best when there is no brood

In fact, most manufacturers recommend treating during times when there is little or no brood. However, beekeepers are well aware that with the delay in the arrival of cold weather, colonies continue to breed until late fall and treatments are delayed, so the varroa mite develops and by the time the miticide arrives, it may already be too late, as damage to the colony is already excessive.

2 – Scratched brood is already doomed and there is little of it

If you choose the right moment, the brood to be eliminated will not be too important. But, above all, you have to take into account that at the end of the season, this brood is very much affected by the varroa mite, so it is practically doomed and will not be very useful for the colony.

3 – A new start with enough time

By removing all varroa-infested brood and with it all or virtually all varroa in the phoretic phase, hives can begin a new batch of egg-laying that will be born without varroa. This is a fresh start that, if done on time, will allow the colonies to enter the fall strong and varroa-free. At this point, time management is key.

With these ideas in mind, beekeepers who practice the scratch brood technique are already getting good results. In general, they work according to this pattern:

When to do it

The time must be chosen very carefully and each beekeeper will choose his or her own according to his or her knowledge of the terrain, the weather and the behavior of the bees. However, as a general rule, it should be done at the end of the season, after the harvest, in September or early October, when there is little brood in the hives. If you wait any longer, the cold will surprise the bees and they will not have time to raise a generation of bees to face the winter.

What to do

You take advantage of the bees’ cleaning instinct to generate a total vacuum of capped cells. Any cells that contain brood are broken up and the hive is free of any cells that might be hiding varroa mites. It should be noted that varroa mites hide in the cells when they are about to be capped, so there may also be mites in the brood that is about to be capped. For this reason, it is also advisable to scrape the open but already developed brood and make it unusable.

How to do it

The operation is very simple: with an unsealed comb (or with a scraper) break the lid of the brood with force. It is very important to do this conscientiously, penetrating deep into the cells. And it must be done without mercy: no sealed brood should be left in the combs. The combs are then put back into the hive, where the bees immediately start cleaning the cells, removing wax remains, larvae and – most importantly – varroa mites. An acaricide treatment is then applied. This can be an organic or synthetic active ingredient, but it must always be on the list of approved medicines for treating varroa mites.
Finally, to ensure a good start after the treatment, the colonies must be given a stimulating diet.

This is to give the colony a chance to become almost completely free of varroa mites at a time when it still has the vigor to raise a new generation of bees. The capped and larger brood is scraped off, but all the newly laid eggs and young larvae still on the larval papilla survive and form the first line of new brood. The queen, by the way, continues to lay eggs and will soon replace what was lost. Beekeepers who use this method ensure that the colonies restart with great strength and that the new bees are stronger and work harder because they are healthier.

3 – Advantages and disadvantages of brood scraping

As you can see, the method is aggressive, its advocates, however, cite its many advantages:

It quickly heals the hive

By forcing the bees to clean the scratched cells, the colony’s cleaning instinct is stimulated. The immediate action of the miticide adds to this cleaning impulse, so the health of the hive improves rapidly.

Cheap

Proponents of brood scraping consider it the most economical method: it reduces the number of treatments and increases the effectiveness of the drugs used, making it more cost-effective.

Less resistance

Reducing the use of drugs limits the ability of varroa mites to develop resistance to these active ingredients.

More sustainable safety

The experience of beekeepers who use this method is that once the treatment is applied, they do not have to worry about varroa mites until the following spring.

On the other hand, opponents of the method believe it should not be used and cite its main drawbacks:

Unnecessary cruelty

The main argument of the opponents of the method is its excessive cruelty. They believe that killing bees is not a way to control a disease. However, advocates of scratch brood insist that most scratch brood is already doomed to death because of its high level of parasitism.

Exposure to deformed wing virus

Varroa mites are known to be a vector for the entry of other viruses, including DWW or deformed wing virus. And it appears that cell disruption may contribute to their spread.

Waste of resources

Many critics of scratch brooding say it is a waste of resources. Bees have to produce a lot of food and a lot of heat to produce the brood, which is then killed. In response to this, beekeepers who favor the method point out that, in fact, much of the food in the damaged cells, and even in the body of the larva itself, is reabsorbed by the colony, so that it receives a substantial supply of protein.

There are alternatives: remove the combs and cage the queen. Opponents of scraping point out that there are other, less painful methods, such as removing combs containing brood or caging the queen. The former involves removing all brood combs from the apiary, which is equivalent to eliminating the brood.

Proponents of brood scraping point out that in reality, brood that is removed will also die, even if from starvation or cold. In addition, frames containing vital food supplies are removed from the hives, creating a logistical problem for the material removed. As for caging the queen, this is a well-known method: the queen is isolated on a comb so that she cannot lay eggs. The amount of brood is reduced in a few days and can be treated. For advocates of scraping, this method results in a complete cessation of brood for several days, which means the colony loses time to recover after treatment.

Until more solid results are published, brood scraping remains a controversial but, for many, very effective method. What do you think about couvin scraping? Leave us a comment on facebook.