Cattle herds on summer pasture are currently experiencing a second peak of fly activity, which can affect their performance. K-State Veterinary Entomologist Cassandra Olds says they suggest rotating chemicals every year.

Olds says switching ear tags now might be impractical, but other treatment approaches can be helpful as long as you use chemicals from the same class.  Olds says you want to make sure you tag both ears so both sides of your cattle are exposed to the insecticide.