218 



Till'. AGRICULTURAL NEWS. 



.1 1 i.\ 



1915. 



INSECT NOTES. 



PESTS OF PEAS AND BEANS. 



In ,i recent number of the 'Agricultural News (see i 

 for Maj s . p. l"il) attention was directed to the weevils 

 which attack stored peas and beans, and one of these, the 

 cowpea weevil, was figured, Since the appearance oi that 

 article stored pigeon peas have been reported from St, \ inci at 

 us being attacked by an insect which on examination proves 

 to be the species mentioned above, Bruchuz chin en sis; and 

 .i sin. ill -uppK of pigeon peas for planting, sent to the 

 Imperial Commissioner from Antigua, proved to be 

 badlj infested with the four-spotted bean weevil (Bruchus 

 qvadriviaculiitus). 



It is to be expected that the several species of bean and 

 pea weevils which occur in the West Indies will be found to 

 attack beans and peas generally. At the present time 

 B. chiiunsis is known to attack pigeon peas and cowpeas, and 

 B. r/ua-lrimaculutus to attack pigeon peas. 



The use of naphthalene instead of car 

 bon bisulphide as a protection for stored 

 seed against the attacks of these insects 

 , is indicated in the Agricultural N"ew$ in 

 the article referred to above, and it 

 would seem that this substance should 

 prove a must useful insecticide foi such 

 insects as the cowpea weevil and the 

 four-spotted bean weevil. These insects 

 are alike in their habit of infesting the 

 glowing grain in the tield, and developing 

 Successive broods in the stored seeds. 



This development r,m probably 1»' 

 checked at once by the use of naphtha 

 lene,but the point needs to l.e proved by 

 careful experimental trials. 

 On reference to the article in the Agricultural Netos 

 already referred to, it will lie seen that when used at the rate 



of 1 tt>. to 40 bushels of grain, naphthalene afforded a very 



satisfactory protection for stond corn. In this instance the 

 naphthalene was used in cloth bags, each containing J-fl). 



It seems probable that, used at several times that strength, 

 say, 1 lb. or more for each bushel of grain confined in tight 

 receptacles for a few days, the insects in peas and beans 



Would be killed, and the injury which OCCUrs after the grain 



is stored thus be entirely prevented. 



Naphthalene is also recommended by it- cheapness and 



its Safety. It could be used OVCl and over again, and it is not 

 explosive like carbon bisulphide. 



Fig. 



PEA 



'.1. Till ('ow 



Weevil. En- 

 larged. {From 



U. S. Dept. 

 of Agriculturi ) 



I n. in. Tilt: I'm i: SPOTTED BeAH \Vi:i:\ ii.. 

 ii. adult: h larva: c, pjipa. All enlarged 



{From U. S. Department of A gricultw 



The economy in the use of naphthalene as an insecticide 



in stored grain results from the method ofapplying it. This 



consists in enclosing. the desired amount oi naphthalene in 

 a bag of suitable size. The bag might be made of muslin, 

 in the small sizes, and of ordinary burlap or sacking in the 

 larger -i/es. Wlcn used a- , preventive in stored grain at 

 the rate ol lib. to 10 .bushels grain as mentioned above, the 



naphthalene Was employed in \ lb. lots; but if it were desired 

 to kill insects already in the grain, the larger dose oi lib. to 

 1 bushel, with tin naphthalene in 111', lit-, should be tried. 



Experiments would soon show how effective this treatment 



would be, ami at so the length of time necessary to accom- 

 plish the desired object. At tile end of this period the 

 large bags of naphthalene could be taken out and the 

 try protection' Afforded by the smaller doses. In this 

 way very little of the insecticide i- used at each application. 



It must be borne in mind that in all fumigaton 

 operations it is necessary to use tight receptacles, and in 

 storing beans and peas as well a- corn, infection and 



re-infection will occur unless suitable storage container- are 

 used. 



In connexion with tin- attacks of these two sp s if 



would seem that naphthalene would prove to be a most useful 



insect aide. 



Another insect pest has been recently reported as 

 attacking beans. This report coin. - from St. Vincent, where 

 imported seed "t pole Lima beans had been planted for 

 trial in the plot- at the Experiment Station. Specimens 

 forwarded to the Imperial Department of Agriculture prove 

 on examination to be a Cryptorhynchus similar t" that 



recently reported as attacking cassava {Agricultural Xurs 

 for May S). 



The following is quoted from tin: memorandum ol the 

 As-istant Agricultural Superintendent, St. Vincent, in 



regard to the larvae of a ( 'ryptorhynchus I tie attacking 



the stems of beans ut the Experiment Station: — 



'A small beetle grub tunnels the stem, beginning prob- 

 ably in the root, and cause- t he plant to break near the ground, 

 and the leaves to turn yellow and fall off. 



'The adult beetle wa- discovered on the -teiii- ol several 

 plants, and "ii the ground near the base oi the stem. In 



appearance the beetle resembles the cassava stem borer, but 

 is slightly smaller. A stem which has been attacked can 

 often be recognized by -mall brownish punctures in the -t. in. 



and by the enlarged nodes in which the grub is usually 

 found.' 



The genu- < 'ryptorhynchus i- a large one, containing some 



twenty-seven species in the West Indies, according to a recent 

 Catalogue.* Oi these, several are known to occur in the Lesser 



Antilles, and the records now indicate the fond plants of live 



of them. One attacks sweet potato, another is a borer in 

 the orange tree, another is a borer in the woody stems and 

 branches of ornamental crotons, another attacks cassava 

 stem., ami the last reported attacks beans. 



This recently discovered species has not been investi- 

 gated, and sonsequently nothing is known as to its habits. 



A careful watch shouM be kept by everyone interested in 



''.in cultivation for the appearance of this pest, and even 

 effort -h"iild be made to learn as much as possible about its 

 life-history, habits, and food plants other than cultivated 

 beans 



11. A. B. 



" I'lelnnilial \ li-l ,.t I he Coleoplela of the West Indie- a- 



i' .1 bo Ji an by 1914, by Chas. W. Leng, Hon. Curator 



of Coleoptera, and Andrew -I. Slut, id, ,. Vssistaut. Published 

 a- ,i Bulletin of the American Museum of Natural History. 



