Bestrijding van nederlandsche insecten met derris

Summary

• 1. In the introduction the origin and character of the insecticid, called Derris, is described; instructions are given for the preparation and the use of

• a. Derris dust (a mixture of Derrispowder and talc, clay, etc.);

• b. Derrispowder suspended in water as a spray;

• c. Pure rotenone suspended in water by means of acetone, also as a spray.

• 2. A survey is given of the possibilities of controlling a great number of injurious insects in Holland by Derris dusts and sprays. Although the control practice by means of Derris has been applied already to the caraway moth (Depressaria nervosa Hw.), the raspberry beetle (Byturus tomentosus F.), the alder leaf beetle (Agelastica alni L.), the cattle grubs (Hypoderma spec.), to various kinds of vermin (fleas (Pulicidae) and lice (Mallophaga), living on domesticanimals, and to a few other insects, the writers should like to point out that by means of the above-mentioned methods a much larger amount of insects might be successfully combatted.

• 3. In general there come into consideration for controlling with Derris: a great deal of caterpillars of both butterflies and moths (Lepidoptera); the larvae of saw-flies (Tenthredinidae); ants (Formicidae); leaf beetles (Chrysomelidae); leaf bugs (Anthocoridae); aphids; thripses (Thysanoptera); cockroaches (Blattidae) and among theCrustaceae: the water- fleas (Daphnia sp.).

  Not to be controlled by Derris are: some caterpillars (for instanceArctia caja L.); beetles living in foods and drugs (Dermestes lardarius L.,Necrobia rufipes Dg.,Calandra granaria L., etc.); many flies and midges (Diptera), except the cattle grub; mealy bugs (Coccidae).

• 4. As concerns the way of applications, in the majority of casesdusting with a Derris dust containing 0,75 to 1% rotenone is to be preferred, e.g. if applied in controlling caterpillars, saw-flies, leaf beetles, leaf bugs, cockroaches, ants, etc.

• 5. If, in dealing with the above-mentioned animals, the process of dusting meets with difficulties,spraying with Derrispowder or Derrisextract mixed with water may be applied with success. Thus, aphids and spinning mites (Tetranychidae) often will appear to be moderately susceptible to dusting with Derris; in these cases, an application of a Derris spray, containing an amount of rotenone 1\3n5000, is advisable.