1mass noun An insecticide containing rotenone, made from the powdered roots of certain tropical plants.
- ‘This consisted of picking off the mature caterpillars and feeding them to the hens, and a liberal application of derris powder.’
- ‘Jam laced with derris, camphor, citronella or pepper also makes an effective bait.’
- ‘Second, spray the tree with derris, which is widely available, when roughly half the flower petals have fallen.’
- ‘The solution for all is to spray with derris immediately any problem is noticed, plus a precautionary spraying about a week before the plants flower.’
- ‘Spray with insecticidal soap or derris as a last resort.’
2A woody climbing plant of the pea family, which has tuberous roots from which the insecticide derris is obtained.
Genus Derris, family Leguminosae
- ‘By the mid 1800s, the heads of chrysanthemum flowers were used to obtain pyrethrum, and rotenone was extracted from the derris plant.’
- ‘The insecticidal properties of Derris roots were first discovered in 1848 and the plant was first used against the nutmeg caterpillar.’
- ‘For rotenone is no post-war insect killer cooked up in a corporate lab, but a natural product, extracted from the derris plant, and a mainstay of organic farms and gardens.’
Mid 19th century (in derris (sense 2)): modern Latin (genus name), from Greek, ‘leather covering’ (referring to the plant's leathery pods).