PLANTS HSTSECTICIDAL PROPERTIES. 53 



Zanthoxylum clava-herculis L. Rtjtaceae. Synonyms: Z. carolinianum Lam., 

 Fagara clava-herculis Small (U. S. P.), Z. fraxinifoliiim Walt., Z. tricar -pum 

 Michx. Prickly ash. Hercules-club. Southeastern United States. 



Riley (71, p. 185) reports that the powdered leaves seemed obnox- 

 ious to cotton caterpillars. 



Zea mays L. Poaceae. Indian corn. Maize. 



Chittenden (16, p. 8) , quoting Bruner, says that corn meal, dusted 

 on cabbage plants in the morning while dew is on, causes the im- 

 ported cabbage worm to drop off and thus it protects the plants till 

 washed off by the rain. 



Scott, Abbott, and Dudley (83, p. 13) found corn meal ineffective 

 against roaches, and Abbott (1, p. 11) found cornstarch ineffective 

 against the dog flea. 



Zygadenus venenosus S. Wats. Liliaceae. Zygadenus. Western United 



States. 



The writers' results are given on page 24. 



GENERAL SUMMARY. 



Since 1915 the writers have determined that the following species 

 of plants, when properly prepared and used, are efficient against 

 certain species of insects : Quassia (Aeschrion excelsa) , amianthium 

 (Chrosperma muscaetoxicum) , pyrethrum or insect powder (Chry- 

 santhemum cinerarias folium) , " cube," two species of clerris (Derris 

 elliptica and uliginosa) , common tobacco (Nicotians tabacum),sgiba,- 

 dilla (Schoenocaulon officinale) , and white false-hellebore (V eratrum 

 album). Other writers report the following species of plants to be 

 efficient against certain insects: Two species of Chrysanthemum (coc- 

 cineum and marschallii) , also used for making insect powder, clove- 

 tree (Caryophyllus aromaticus), Claviceps purpurea, " cucaracha " 

 herb of Mexico (Haplophyton cimicidAMn) , redcedar (Juniperus vir- 

 giniana), and American false-hellebore (V eratrum viride). 



The writers found the following plants to have some insecticidal 

 properties, but they proved to be inefficient against the insects used 

 in the tests: Balbec, a Honduras fish-poison, sandboxtree (Hura 

 crepitans), margarita (Karwinskia humboldtiana) , common matri- 

 mony-vine (Lycium halimi folium) , tomato (Lycojyersicum esculen- 

 tum), Madhuca sp., chinaberry (Melia azedarach) , moetoepoe, necoe- 

 tae, Pangm??i edule, and common castor-bean (Ricinus communis). 

 Other writers report the following plants to have insecticidal proper- 

 ties, but it is doubtful if any of them will prove efficient for practical 

 work: Aconite (Aconitum napellus), Aloe spp., two species of 

 Anthemis (cota and tinctoria), butterfly weed (Asclepias tuberosa), 

 pepper (Capsicum sp.), swallow-wort (Chelidonium majus), three 

 species of Chrysanthemum (achilleae, myconis, and parthenium), 

 Cinchona succirubra, larkspur (Delphinium sp.), black hellebore 

 (Helleborus niger), Jamaica fish-poison (Ichthyomethia piscipula), 

 henbane (Hyoscyamus niger), German false-camomile (Matricaria 

 chamomilla), Aztec tobacco (Nicotiana rustica), soapbark (Quill aja 

 saponaria) , lavender-cotton (Santolinu, chamaecyparissus), sassafras 

 (Sassafras variifolium) , and potato (Solamum tuberosum) . 



