RED-SQUILL POWDER IN RAT CONTROL 



By James Silver, Associate Biologist, and J. C. Munch, Consulting Pharma- 

 cologist, Division of Predatory-Animal and Rodent Control, Bureau of Bio- 

 logical Survey 



INCREASED use in this country of powdered red squill for killing 

 rats, following its recommendation by the United States Depart- 

 ment of Agriculture, has resulted in many inquiries concerning its 

 properties, characteristics, and use, and particularly its effect upon 

 other animals. This leaflet has been prepared to assist in making 

 replies. 



The principal rat poisons on the American market in 1923 were 

 phosphorus, arsenic, barium carbonate, and strychnine. At that time 

 the Department of Agriculture recommended barium carbonate as 

 the most practical rat poison, because it is effective when properly 

 used, inexpensive, and less dangerous to human beings than the other 

 three. In spite of its relatively low toxicity, however, and the fact 

 that its effects are readily counteracted by a simple antidote, do- 

 mestic and other valuable animals were being killed and human life 

 menaced through its widespread use. A raticide devoid of such 

 dangers was needed, and inquiry by the department into many known 

 j)oisons led to an exhaustive study of red squill (Urginea maritima) . 



The results of this investigation, which began in 1923 and con- 

 tinued into 1929, are recorded in detail in a technical bulletin of the 

 department. 1 Red squill had been known in Europe for many }'ears, 

 but apparently its use had not become popular, owing to extreme 

 variation in the toxicity of available products. The studies carried 

 on by the Department of Agriculture, however, showed that a uni- 

 formly toxic powder can be produced when the red-squill bulbs are 

 dried under controlled temperature conditions, and that although the 

 powder is effective in destroying rats it does not seriously endanger 

 other animal life. Because of the publicity given to the progress of 

 the investigation and the excellent results obtained in the early 

 stages, powdered red squill is now being manufactured in large 

 quantities in the United States. So far as known, the first of these 

 commercial red-squill powders was placed on the American market 

 in 1926, and in less than five years these products took a leading place 

 among rat poisons on this market. 



Red squill, called also scilla, or sea-onion, is a perennial plant 

 belonging io the lily family. It grows wild among the hills border- 

 ing the. Mediterranean, especially in southern Italy, 

 What Is Red Sicily, and in Sardinia, and along the Libyan coast. 

 Squill? The onionlike bulbs occasionally attain a weight of 



10 to 15 pounds, although those that find their way 

 into commercial channels usually weigh from 1 to 8 pounds. They 

 are gathered usually during the dormant period in summer and early 

 in fall. The pointed, bladelike, deep-jrreen leaves (fig. 1) dry up 

 before the flower blooms in spring. The small flowors. which are 



1 Technical Bulletin No. 134, Rod-Squill Towdcrs as Raticides. For sale by the Super- 

 intendent of Documents, Government Printing Office, Washington, D. C, at 10 cents a copy. 



2 



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