The late-summer peak of the growth of Varroa mites population in the bee colonies, which can be as fatal as the spring peak.
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 the quantity of the mites in the bee families in the apiary is the maintenance of young families which are not inclined to switch to the swarming state. This allows families to rear very few drone broods, 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, a possible method for improving the condition of the bees is expanding of the nest, which leads both to a decrease in swarming mood and to cooling of the areas where drone broods may be present. It is also appropriate to use building frames, in order to remove periodically drone broods 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 there 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, the situation repeated, 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 in 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 used to oppose 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 a method which has proven itself perfectly in Central Europe when working with Karnika bees. This is the method of removal of the sealed brood!!!