| 释义 |
Definition of derris in English: derrisnoun ˈdɛrɪsˈdɛrəs 1mass noun An insecticide containing rotenone, made from the powdered roots of certain tropical plants. Example sentencesExamples - 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.
- This consisted of picking off the mature caterpillars and feeding them to the hens, and a liberal application of derris powder.
- Spray with insecticidal soap or derris as a last resort.
- 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.
2A woody climbing plant of the pea family, which has tuberous roots from which the insecticide derris is obtained. Genus Derris, family Leguminosae Example sentencesExamples - 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.
- 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.
Origin Mid 19th century (in sense 2): modern Latin (genus name), from Greek, 'leather covering' (referring to the plant's leathery pods). Definition of derris in US English: derrisnounˈderəsˈdɛrəs 1An insecticide made from the powdered roots of certain tropical plants containing rotenone. Example sentencesExamples - 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.
- Spray with insecticidal soap or derris as a last resort.
- 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.
- Second, spray the tree with derris, which is widely available, when roughly half the flower petals have fallen.
2A woody, climbing plant of the pea family that bears leathery pods and has tuberous roots from which this insecticide is obtained. Genus Derris, family Leguminosae Example sentencesExamples - The insecticidal properties of Derris roots were first discovered in 1848 and the plant was first used against the nutmeg caterpillar.
- By the mid 1800s, the heads of chrysanthemum flowers were used to obtain pyrethrum, and rotenone was extracted from the derris plant.
- 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.
Origin Mid 19th century (in derris (sense 2)): modern Latin (genus name), from Greek, ‘leather covering’ (referring to the plant's leathery pods). |