The following is a direct quote from ScientificBeekeeping.com and the article is titled
''A Test of Late-Summer Varroa Treatments''
Let me cover the results of the late and informal testing of the oxalic strips and essential oil pads first:
Oxalic/glycerin Strips
Although we ran no controls for this small informal test (and could thus not calculate efficacy), our results (Table 2) reflected the results of Maggi, who recorded efficacies of over 90% after 6 weeks of treatment. The strips are relatively simple to make and install (Fig. 12). However, even after several months, the bees had not chewed them out. This may have the advantage of extending the treatment (since they still had oxalic acid crystals on the surface), but raises a huge caution to beekeepers not destroy oxalic acid?s utility as a mite treatment by leaving them in the hive.
One of the newest weapons in our arsenal against varroa are oxalic/glycerin strips, which provide release of oxalic acid over an extended period of time.
Oxalic/glycerin strip test
Treated 1 Dec
Hive No. Nov mite count Dec mite count
39 25 1
41 23 0
52 40 1
69 22 1
Table 2. Results of testing oxalic/glycerin strips on 4 hives. Note that at this time of season, we would have expected mite counts to drop to some degree even without treatment. However, these results, as well of those of Maggi, are certainly encouraging!
Practical application and a cautionary warning: the oxalic/glycerin strips show great promise, and I will continue testing. The downside, however, is that some beekeepers will of course keep them in their hives continuously (especially since the bees do not remove the strips), which will apply a strong selective pressure on varroa to develop resistance mechanisms to acids. Beekeepers have a history of shooting themselves in the foot by overusing treatments without rotation, resulting in resistant mites and bacteria. If you use these strips, please do not leave them in your hives continuously, as you may then inadvertently be breeding mites resistant to acids, which could ruin it for the rest of us.