What flowers contain pyrethrin?

What flowers contain pyrethrin? Pyrethrum is also the name of a natural insecticide made from the dried flower heads of Chrysanthemum cinerariifolium and Chrysanthemum coccineum. Its active ingredient are pyrethrins….Common names Pyrethrum. Pyrethrum daisy. Dalmatian pyrethrum. Dalmatian chrysanthemum. Dalmatian insect flower. Dalmatian pellitory. Big daisy. Do all chrysanthemums have pyrethrum? Read more…

What is a Strowger switch?

What is a Strowger switch? The Strowger switch uses two telegraph-type keys on a telephone set for dialing. Each key requires a separate wire to the exchange. The keys are tapped to step the switch in two stages. What are the Strowger switching components? The Strowger switch consisted of essentially Read more…