Harka-Verm Liquid: A liquid wormer for use against roundworm and hairworm. Mix 6ml Harka-Verm to 2 litres of drinking water for 3 days. 1 bottle will treat up to 90 pigeons or 180 cage birds over a 3 day period. Not to be used during moulting season, as may cause fretmarks. Contains Levamizole. A well-know brand name in the British pigeon world, Harkers is the UK's bestselling supplier of pigeon products since 1954. Distinct packaging and branding