Vector and Pest Control in Refugee Situations (United Nations High Commission for Refugee, 1997, 124 p.)
 (introduction...) Preface 1. Introduction 2. Factors influencing the spread of vectors in refugee camps 3. Arthropods of medical importance 4. Mosquitos 5. Non-biting flies 6. Lice 7. Fleas 8. Bed bugs 9. Human scabies mites 10. Ticks 11. Other arthropods of medical importance 12. Snails hosts of schistosomes 13. Commensal rodents 14. Organisation of a control programme 15. Pesticides 16. Safe use of insecticides Glossary Bibliographic selection Annex 1. Some arthropods and their importance to health Annex 2. Morphological characteristics of some arthropods of medical importance Annex 3. Reporting form for spraying operations Annex 4. Calculation of the quantity of solution and insecticide for use in treatments Annex 5. Determination of the insecticide concentration for use in a sprayer Annex 6. Preparation of a solution from an insecticide formulation Annex 7. Preparation of a solution from an emulsifiable concentrate Annex 8. Calculation of the quantity and dilution of insecticide for use in impregnation of fabrics Annex 9. Calculation of the quantity of molluscicide for use in a waterway

### Annex 6. Preparation of a solution from an insecticide formulation

In order to prepare a suspension or a solution from a given formulation of a pesticide in wettable powder or emulsifiable concentrate form, the following formula must be applied:

where

X = quantity of formulation necessary
A = desired concentration
B = desired quantity of solution
C = concentration of a.i. in the formulation
D = 1 if X and B are expressed in kg or litres; D=8.33 if X and B are expressed in pounds or US gallons and D=10 if X and B are expressed in pounds or imperial (UK) gallons.

Example:

To obtain 100 litres of a 2.5% solution from an insecticide formulation containing 50% a.i.:

Therefore 5 kg or 5 litres of insecticide formulation have to be mixed with 100 litres of water to obtain the solution at the concentration required for filling the pumps.

N.B. When using powders for suspensions, the powder should be put into a receptacle with a little water, and mixed to obtain a paste. This paste should then be thinned by adding small quantities of water until the desired volume is attained and the resulting mixture poured through a filter into the tank.