"Hence the concentration is always highest where the pad is, and in
this case, at the bottom of the hive."



I use formic acid (MAQS) for its efficacy against mites in capped brood and have worked under the assumption that, in that respect, distribution near and around the capped brood is required and NOD makes that clear with their placement protocol. When treating in late summer, I can sometimes see capped brood just below the top bar where I place strips. Is it possible that placing strips on the bottom board, almost 10 inches away, would work the same? That would certainly make the application much easier. I went looking for some research that would help and found these two papers- Egurasi (2001) and Fries (1989). 

 
Part of the discussion from Egurasi: 

"those treatments that considered a homogeneous distribution of formic acid dispensers showed a greater effectiveness. This agrees with FRIES (1989) who said that one of the principal causes of formic acid low efficacy was related to distance from dispenser to brood area. In this sense, ROSENKRANZ (personal communication) observed that mite mortality inside the cells depended on dispenser position. In this way, when dispenser was put over the combs a great proportion of dead mites was found in the upper half of brood comb; the other way, a high proportion of mites inside cells located in the inferior half of the comb survived." 


VARROA JACOBSONI CONTROL WITH FORMIC ACID USED IN DIFFERENT APPLICATION WAYS IN SUBTROPICAL AND TEMPERATE CLIMATES

M. EGUARAS1, M. LABATTAGLIA2, C. FAVERIN1, M. DEL HOYO2, M.A. PALACIO3, M. CARRIN2, G. RODRIGUEZ4, S. RUFFINENGO3, E.L. BEDASCARRASBURE2


Part of the Abstract from Fries: 

"The importance of regulating the formic acid dose in relation to the distance to the combs from the acid source is stressed by the presented results."

Short-interval treatments with formic acid for control of Varroa jacobsoni in honey bee (Apis mellifera) colonies in cold climates [1989]

Fries, I. (Sveriges Lantbruksuniv., Uppsala (Sweden). Inst. foer Husdjurens Utfodring och Vaard)


Bill Hesbach
Cheshire CT

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