The late-summer peak of the growth of Varroa mites population in the bee colonies, which can be fatal as well as the spring peak.

In our previous article, we focused mainly on the spring peak in the growth of the mites population in the bees families and the problems associated with it. However, the spring peak of the growth of the mites population is not the only one. There is a second such a  peak after the end of honey collection and removal of honey combs . At this point, the family has enough honey, pollen and again free space for the bees to start mass rearing of brood of their spring shift. This is also a very dangerous moment, often leading families to death. In the period after the honey harvest, families have a sharp increase in the quantity of brood, almost similar to the spring, pre-harvest build-up....

At any time of the year, an important method of reducing of the quantity of the mites in the bees families in the apiar  is the maintenance of young families which are not inclined to switch to the swarming state. This allows families to rear very few drone brood, which, if it is a lot and if it is well heated by the bees, causes a sharp increase of the mites population.

In the spring, possible method for improving the condition of the  bees is expand of the nest, which leads both to a decrease in swarming mood and to cooling of the areas where drone brood may be present. It is also appropriate to use building frames, in order to remove periodically drone brood infected with the mites.

But, the death of bees can occur at the moment at which this is least expected ... It would seem, that a strong family worked perfectly at the honey collection, gave a lot of marketable honey ... And after removal of honey combs, it suddenly begins to simply melt before our eyes ...

This is exactly what happened with the 8-1 family in our experimental apiary ...

Despite the simple removal of drone brood at the beginning of June, the growth of the mites population, having slowed down sharply in June-July, continued in August ...

The family did an excellent job at honey collection, giving 60 kilograms of marketable honey in a stationary apiary. During the honey harvest, we observed a mites drop and a fairly large number of bees infected with the wing deformity virus. But the situation during the examinations did not seem critical. The small number of bees in the hive during inspection could be associated with the fact that many flying bees work at this time on nectar collection. There are a lot of them, as the amount of brood reduced, due to the loading of a part of the nest with honey.

Our control of the families of the experimental apiary continued ... By August 1, began a sharp increase in free fall of mature and immature mites  (pic), which, according to our observation, is a sign of the worst case for us - a powerful reproductive flash in the mites population. By August 1,  free fall of the mites of both types averaged 10 mites per day, by August 9 - 20 mites per day, by August 17 more than 100 mites per day ... In fact, repeated situation, which led to the death of the E-1 family, with the exception of lack of drone brood at this time !!!

Since August 24, the family has been treated twice with an interval of about a week with a preparation containing amitrase. At the same time, the daily amount of mites drop of both types ( mature and immature) significantly exceeded 100 mites per day. But, despite the treatment carried out, by September 25, only a handful of bees remained in the hive, which fully corresponds to the picture of the so-called Collapse of the Bee Families. The too late treatment did not help to compensate the death of brood and young bees, which were born with wing deformities affected by the virus. Young bees went out and never returned to the hive. The family just melted before our eyes ... 

What can be opposed to the growth of the Varroa mites population during the honey harvesting season, when there is no possibility to use chemicals ...

We think that it is necessary to use the method, which has proven itself perfectly in Central Europe when working with Karnika bees. This is a method of removal of the sealed brood.

Removal of frames with sealed brood, which can be carried out during the period of  growing of bees families before the main honey collection with the goal to prevent swarming and to create offshoots, also sharply reduces the number of Varroa mites in bee colonies, and significantly contributes to the fact, that disease will not take a threatening character in the main families even in the absence of other Varroa mites' control measures.

In addition, holding such an event in June, before the main honey collection, can, under certain conditions, increase honey productivity by reducing brood rearing, and families from which the brood was selected, can be treated with formic acid ( if remaining before the main honey collection time allows this), which will be very effective at this stage. After all, there is no sealed brood in the family and all the mites are on the bees and are accessible for acaricidal preparations.

In the process of honey collection, bees themselves usually create conditions that are not very good for the reproduction of the mites ... This can be seen from the graphs of the mites drop in all families. But even at this time, it is possible to influence the mite population using methods of temporary limitation of queen's egg laying and removal of sealed brood. Unfortunately, such measures during the period of honey collection cannot be radical, otherwise there will be losses of marketable honey due to the weakening of the strength of bee colonies.

At the same time, to offshoots, in which all sealed brood from the apiary was collected,  can be given sealed queen cells or they can rear new queen by themselves. Moreover,  there will be no brood for about two to three weeks for natural reasons. At the same time, all sealed brood  will turn into young bees, on which the entire mites population of your apiary  will be! There is no marketable honey in these young families, so nothing prevent to treat them with any acaricidal preparations, both natural (formic acid) and chemical.

Thus, you will free the working families from 70-80 %% of mites by removing sealed brood and you can destroy 70-80 %% of remaining mites by treating the bees with formic acid ... At the same time, young families created on the basis of sealed brood, after the release of young bees and their subsequent treatment with acaricidal preparations, and best of all, with the same formic acid, will also lose 70-80 %% of Varroa mites.

This technique can simultaneously extinguish both the first - spring and second - summer peaks of Varroa mites population growth.

Thus, to keep bee colonies healthy with minimal use of chemical acaricidal preparations, it is imperative to carry out exactly two blocks of events, each of which is important in its own way. And never forgetting especially about the second - the summer peak of the mites population growth. Of course, the spring peak of the mite population growth must be suppressed unambiguously. But if a strong treatment of bees against Varroa mites was carried out in the fall and there is not much of the mites left till the spring, then this peak may pass unnoticed or the signs of its presence will be blurred...  And in such situation the second peak, which usually occurs long before the autumn anti-varroatous treating of the bees  can become lethal for the bees families. A family of bees may simply not live up to see it !