>From ccc12748@vip.cybercity.dk Mon Sep 8 16:44:35 1997 From: "David M. Thomas" Here is a method of varroa treatment using Oxalic 3%. I use it every year in week 34 i.e. beginning October. It does not work on closed brood but it knocks off the other nasties like nosema and tracheal mites as well. so I am currently getting better winter survival than my peers in the local area. (USE WHERE LEGAL, USE AT OWN RISK, ASK SOMEONE BEFORE YOU USE) VARROA TREATMENT with 3% Oxalic acid solution. Preparation Oxalic acid crystals or powder. 30 grams = 1 oz. Water ( de-mineralised is best but tap water will do). 1000 ml = 1 litre. Add crystals to water and shake until all is dissolved. Hard water will cause a light milkiness due to precipitation of very insoluble calcium oxalate. This effect can be ignored for the purposes of treating bees for varroa. Fill in a bottle and mark the solution as:- 3% Oxalic acid. R 25 Toxic if swallowed. R 21 Harmful in contact with skin. R 36 Irritating to eyes. Mark with a skull and crossbones and the Symbol T. Refer to the Safety Data sheet for oxalic acid attached below. But do not worry as reasonable care will prevent any danger. You will have to drink about sherry glass (50 ml.) of the liquid in order to be lethally at risk. It tastes absolutely insufferably bitter so it is very unlikely that one can ingest sufficient dose to be in danger without observing very definite distaste. Rhubarb and spinach contain appreciable amounts of oxalic acid. The oxalic acid can be neutralised with an antidote which is a 5% solution of calcium chloride. The antidote precipitates the oxalic acid as insoluble calcium oxalate which then cannot be absorbed in the alimentary tract. Observe the following R-Ratings and S-Provisions. R 25 Toxic if swallowed. Antidote 5% calcium chloride to be swallowed immediately after ingesting. R 21 Harmful in contact with skin. R 36 Irritating to eyes. S 13 Keep away from food, drink and animal feeding stuffs. S 20 When using do not eat or drink. S 24 Avoid contact with skin. S 25 Avoid contact with eyes. S 26 In case of contact with eyes, rinse immediately with plenty of water and seek medical advice. S 27 Take off immediately all contaminated clothing. S 28 After contact with skin, wash immediately with plenty of water. S 36 Wear suitable protective clothing. S 39 Wear eye/face protection. S 42 During fumigation/spraying wear suitable respiratory equipment. S 45 In case of accident or if you feel unwell, seek medical advice (show the label where possible). Toxic substances /T+, T, Xn/ Legislation applying to chemicals distinguishes three categories of toxicants: .- highly toxic substances (R 26 - R 28), danger symbol T+, .- toxic substances (R 23 - R 25), danger symbol T, .- less toxic substances (R 20 R 22), danger symbol Xn,. Highly toxic substances are those which can cause grave acute or chronic health damage or death almost immediately if inhaled, swallowed or absorbed through the skin in small amounts. Toxic substances are those which can cause considerable acute or chronic health damage or death if inhaled, swallowed or absorbed through the skin in small amounts. Less toxic substances (noxious substances) are those which can cause restricted health damage if inhaled, swallowed or absorbed through the skin. A dilute solution of oxalic acid can be so dilute as to demand just Xn-Harmful markings. The solution used is dilute but it is preferred to label it a class above as T marked, in view of the toxicity of the pure substance. Application Use in the early spring or the late autumn when there is no brood which can be exposed to the liquid. Spray as finely as possible from a hand held spray 5- 8 ml on each frame surface. Ensure that all bees are exposed and that no frame side is left out. The outside temperature should be at least 10 degrees but high temperatures should be avoided so that all bees are home while the treatment is given. All bees should be treated. i.e. all bees in all the hives in the immediate vicinity. The efficiency of this method is very high and results in varroa mortality of around 99%. There is a very limited danger of reintroduction when treatment is done at the final visit before wintering the bees. Radecki has measured the remnance of oxalic acid in the honey from 12 treated families The remnance in all 12 cases of oxalic acid in honey is extremely low and under the limits of detection of 25 mg per Kg honey. The acid is insoluble in wax and cannot b e detected in wax. This treatment is a very good backup for formic acid treatment which is carried out after the last honey has been removed. Our local Association in Denmark has a varroa treatment day in week 32. where 65% formic acid is used on so-called Krämer sheets. This is the first week in August because our main flow is over at the end of July.