The use of Formic acid

 This is from a work made by Ingemar Fries in 1989.


Sixty-four honey bee colonies infected vith Varroa in six different apiaries were exposed to seven different treatments in accordance with the table.

IMP= Illertisser Milbenplatten containing 14,2 g waterfree FA.
20 g, 30 g,= dosage of free FA applied on fibre material in an 85% water solution.
Intervals in days, and number of treatments.

Treatment Number of colonies Agent Dose, grams Interval and number of treatment Place of application Distance form combs, mm
A 20 IMP 56,8 1x4 Under combs 70
B 9 IMP 56,8 4x4 Under combs 70
C 7 IMP 56,8 1x4 Above combs 10
D 10 IMP 42,6 1x3 Under combs 10
E 5 20 ml 81,3 1x4 Under combs 70
F 5 30 ml 121,9 1x4 Under combs 70
G 8 20 ml 81,3 1x4 Under combs 10


The colonies were treated, with brood present, early in the morning in late August with temps varying from +14 to +18 C. The results from treatment were estimated by counting the mite downfall within 12 days after treatment. 12 days were used since sealed brood will hatch within that peroid and the effect of FA on mites inside the brood cells will be included. In late October, in broodless condition, all colonies were treated with Perizin and the mite downfall counted. The total mite population was estimated after a 95% efficiency of Perizin treatment.

Treatment Downfall FA Downfall Perizin Effect %
A 965,8 +-201,7 463,6 +-130,3 63,9 +-6,1
B 596,9 +-111,3 421,2 +-125,6 61,4 +-6,9
C 2 149,1 +-440,9 217,9 +-57,7 90,2 +-3,0
D 392,8 +-43,3 22,4 +-4,7 94,5 +-1,0
E 364,2 +-190,6 43,2 +-21,1 84,7 +-5,6
F 1 098,0 +-592,0 11,0 +-4,1 96,6 +-1,6
G 2 028,4 +-491,0 64,1 +-17,4 96,3 +-1,1


Treatment A and B did not differ significantly, but both were less effective than all other treatments. No significant differences were seen between treating from above (C) or from below (D), or between treating colonies every day (A) or every fourth day (B) using the same doses and distance in both comparisons.

A simple analysis shows that both the doses and the distance of application from the combs significantly influenced the results.

Possible effects from treatment on queen losses were studied in 91 separate colonies that were on a long time experiment with FA. In the 91 colonies where the presence of the queen was investigated after 4 treatments with IMP, 5 colonies had lost their queen (5,5%), probably due to the treatment.