Tests of Insecticides for the Control Goat Lice in 1957 and 1958 c

Abstract

To investigate reports on resistance or goat biting lice ( Bovicola caprae (Gurlt) and B. limbatus (Gerv.)) to chlorinated hydrocarbon insecticides, goats from two ranches near Kerrville, Texas, were dipped into insecticides at dosages recommended by the Entomology Research Division, U. S. Department of Agriculture. Lice from one ranch were not killed by 0.25% toxaphene, which previously had been very effective. Field tests were conducted with sprays of Delnav® (2,3- p -dioxanedithiol S,S - bis( O,O -diethyl phosphorodithioate )), ronnel, malathion, Dipterex® ( O,O -dimethyl 2,2,2-trichloro-l-hydroxyethylphosphon- ate), Bayer 21/199 ( O -( S -chloro-4-methylumbelliferone) 0,0 - diethyl phosphorothioate), Sevin®(1-naphthyl N -methyl carbamate), and toxaphene for the control of biting lice and sucking lice ( Linognathus stenopsis (Burm.)) Toxaphene and 0.1% Delnav failed to kill lice. Others were effective within 24 hours on goats with fleece shorter than 10 weeks' growth, and from g to 5 days on goats with longer fleece. Flocks sprayed with 0.5% ronnel, 0.1% Bayer 21/199, and 0.5% Sevin were free of lice at the next shearing (2 to 4 months).