Lactic Acid is a crystalline solid that is readily soluble in water. This acid is generally regarded as a less hazardous substance than other organic acids used in varroa control, but it can cause allergic reactions and cause burns to skin and eyes, it will also cause corrosion and irritation of the digestive tract.

Lactic Acid formula is CH3CHOHCOOH and it is known by several other, but not so well known, names…
2-hydroxypropanoic acid, ethylideneactic acid and 1-hydroxyethanecarboxylic acid.
Lactic Acid Spacial representationLactic Acid is the smallest chemical molecule with an asymmetric or chiral carbon and exists in two stereo isomer versions… The L(+) and the D(-) also known as the R(+) and S(-). The L(+) or R(+) version is one that occurs naturally in animal and human tissues after exercise.
There are two ‘mirror image’ isomers of lactic acid. These both have the same bonding arrangement, but are left and right handed isomers that are mirror images of each other and are called enantiomers.

Lactic acid does not penetrate sealed brood cells.

Using lactic acid for mite reduction in honey bees requires that the bees are in a broodless or swarm like state as, although it is highly effective, it is only effective against varroa mites that are on the adult bees that can be contacted by droplets of acid. If the bees are in a hive then this condition occurs in November or December. Each frame of bees must be removed and sprayed on either side with a 15% solution or the acid can be dribbled along the seems of bees again using a 15% solution. Treatments must be repeated several times. Because of need for frequent application and the large droplet size of spray bottles, a significant quantity is ultimately delivered. This large dose increases the possibility of residues in honey. Small quantities of lactic acid are present naturally in honey and this fact is often used to suggest that lactic acid is a ‘natural’ treatment (however it is wise to remember that there is no such thing as a ‘poison’ per se, but there are ‘poisonous levels’. Careful timing of the treatment is important to minimise this contamination in honey and a withdrawal time of eight weeks from last treatment prior to honey harvesting.