PLANTS INSECTICIDAL PROPERTIES. 47 



Polygonum pennsylvanicuni L. Smartweed. United States. 



"Washburn (93, p. 35) determined that a decoction had no effect on 

 the horn fly. 



Pongam pinnata (L. ) W. F. Wight. Fabaceae. A tree found in India, Ma- 

 layan Islands, and northern Australia, cultivated in Florida. 



The writers' results are given on page 23. 



Prunus spinosa L. Rosaceae. Blackthorn. Sloe. Europe. 



Von Mueller (91, p. 430) reports that it is hardly at all liable to 

 attack by insects. 



Pteridium aquilinum (L.) Kuhn. Polypodiaceae. Bracken. 



In Austria the leaves are placed in the bed as a protection against 

 vermin (6). 



Pulicaria dysenterica (L.) Gaertn. Asteeaceae. Synonym : Inula dysenterica 

 L. Fleawort. Southern Europe. 



Lyons (53, p. 384) calls it an herb insecticide. 

 Passerini (66) found the action of the flower heads uncertain 

 against flies, fleas, and ants. 



Pulicaria vulgaris Gaertn. Synonym: Inula iJiilicaria L. Europe. 



Kalbruner (47) reports that the flowers were entirely inactive 

 against flies. 



Quillaja saponaria Molina. Rosaceae. Soapbark. South America. 



Parker (65. p. 7) used soapbark as a spreader and found that it 

 never killed more than 21 per cent of the prune aphids sprayed. 



Rhinanthus crista-gaUi L. Sckophulaeiaceae. Rattlebox. Northern Eu- 

 rope, Asia, and North America. 



Lyons (53, p. 395) lists it as a plant insecticide. 



Rhus coriaria L. Axacabdiaceae. Sumac. Europe. 



Von Mueller (91, p. 461). quoting Sorauer. says: " Carves records 

 that this plant, when in proximity of vines infested by Phyllo-ce ra 

 vastatrix, destroys this insect." 



Reymond (70) buried a bag of sumac {Rhus sp.) leaves around 

 the base of each apple tree infested with the woolly aphis (Aphis 

 lanigera). He noticed no effect the first year, but the second year 

 the experiment was very successful. He thought that the tannin in 

 the ripe sumac leaves either killed or repelled the aphids. 



Ricinus communis L. Euphoebiaceae. Synonyms: R. vulgaris Mill., R. medi- 

 cos Forsk. Common castor-bean. Southern Asia. 



It is reported (5) that in 1886 this plant was found efficacious in 

 freeing rooms of insect life, the leaves containing a substance which 

 is fatal to flies and other insects. 



Riley and Howard (74? p. 359) quote a medical journal to the ef- 

 fect that in Egypt castor-bean plants, when grown about houses or 

 when the leaves are placed in rooms where mosquitoes are present, 

 are effective repellents, but Howard (44 5 V- %3) denies that these 

 plants when grown about houses act as mosquito repellents. 



