THE MONTHLY BULLETIN. 535 



SWEET POTATO WEEVIL. 



Gylas formicarius Tryon. 

 Bt Frederick Maskew. 



It is a common saying that every one in the world passes through 

 the Ferry Building once in his lifetime. Such statements, of course, 

 are not susceptible of proof. However, we are almost ready to believe 

 that specimens of every insect pest so far recorded eventually find their 

 way into the quarantine station located in the Ferry Building at San 

 Francisco. It would be a coincidence for a vessel arriving from any 

 Oceanic or Oriental port to remain at the dock in San Francisco for 

 a week without some one of the quarantine force finding either in the 

 ship, the freight or in the belongings of the passengers specimens of 

 some insect pest not yet known to exist in the State. Horticultural 

 freight from the Orient makes ideal hunting ground for bug catchers, 

 and the quarantine service has always been fortunate in that its bug 

 hunters, without exception, have all been enamoured of their occupa- 

 tion. The particular pest we are dealing with in this article was found 

 at work by inspectors B. B. Whitney and Lee A. Strong in a shipment 

 of sweet potatoes brought by the S. S. "Nile" from China, and again 

 by inspector Lee A. Strong in a similar lot of sweet potatoes brought by 

 the S. S. "Mongolia" from China on September 6, 1912. This pest has 

 unquestionably been taken and destroyed by quarantine officers many 

 times in the past, but I find no record of the same in the quarantine 

 annals. 



The illustration of the insect in its several stages (Fig. 329) which 

 was reproduced from the original of T. Shiraki's "Injurious Insects of 

 Formosa," volume 1, also shows clearly the destructive work of the 

 larvc^ in the interior of the potato. A superficial view of an infested 

 specimen reveals no evidence of this attack upon the tissues other than . 

 the minute hole through which the larva has entered, and the full 

 ■extent of the ravages is not apparent until the potato is cut open. 



Figure 330 represents an actual specimen of an injured tuber 

 taken at quarantine with four of the weevils in situ. From our hurried 

 observations we are of the opinion that the extensive cavities shown 

 herewith are the work of the adult weevil, and demonstrate clearly its 

 ability to reduce market values, even of stored potatoes. 



Ctjlas formicarius is a very widely distributed' species, and a native 

 probably of Cochin China. Compere has a record of finding it at Bom- 

 bay and also at Calcutta in sweet potatoes offered for sale in the public 

 markets at both of those places. It has also been reported from Mada- 

 gascar, Southern United States, West Indies and Northern Australia; 

 but not yet so far from the sweet potato fields or markets of California. 



It also occurs in the Hawaiian Territory, and was recorded as a pest 



