The efficacy of varroosis control with Apifos strips used in the last year as well as with the new strips was very high. During a 6-weeks exposure of the strips in bee colonies, in group I with re-used strips 95.32% mites fell off on the average. In group II with new strips, the fall of the parasite was only by 2.86% higher. The remaining part of the fall, amounting respectively to 4.68 and 1.82%, was collected from the bottom inserts following fumigation of bee colonies with Apiwarol. The evaluation of bromfenvinphos content in the strips following their withdrawal from bee colonies showed that the amount of active ingredient differed greatly and depended on their multiple use. For the strips used twice (group I), the content of active ingredient oscillated within the range 3.01 to 19.39 mg/strip, whereas for those used once (group II) it was within the range 26.65 to 51.18 mg/strip. Its average level for the first strips was 8.22 mg, whereas in the second ones several times higher – 38.78 mg per one strip. At the same time it should be stressed that only in re-used strips the bromfenviphos content was conditioned significantly (r = –0.551) by the degree of erasure of the microlayer covering them. The bromfenvinphos content found in the strips following a single 6-weeks exposure in bee colonies is sufficient for acquiring the high efficacy of treatment, which is demonstrated by the obtained results.

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