US EPA

1027769 

Journal Article 

The protective effect of arsenic and derris dips against the sheep tick, Ixodes ricinus L 

MacLeod, J 

1947 

Yes 

Annals of Applied Biology
ISSN: 0003-4746
EISSN: 1744-7348 

34 

2 

207-223 

English 

20266410 

10.1111/j.1744-7348.1947.tb06356.x 

Sodium arsenite used at a bath strength of 0.2% As2O3 is shown to protect sheep to a large extent from infestation for periods of from 1 to 2 weeks. Coal-tar creosote dips, though usually effective in killing attached ticks, have no protective effect against reinfestation. Derris, either as ground root or as extract, kills all attached ticks at dilutions down to the order of I part extract in 15,000 of water. At a concentration of 1 part in 5000 it has an effective duration comparable to that of arsenic at 0.2% As2O3. Its maximum effective duration, when applied as an emulsion wash, appears to be 14–17 days.

The addition of wool grease enhances the effective duration of arsenic, but not of derris. The effect of immersion time is important for both arsenical and derris dips, but is especially important for the latter. For full effect with derris washes sheep must be immersed for at least half a minute.

A protective dip is described which markedly lowers the infestation of dipped sheep for about 3 weeks.