186 



THE AGRICDLTURAL NEWS. 



June 8. 1912. 



INSECT NOTES, 



THE ARROWROOT WORM. 



The arrowroot worm [Calpodes etliliui) — see Fig. 1 — is 

 known in the United States as the larger canca leaf-roller, 

 and this name appears as tlie title of an interesting circular 

 (No 145) by F. S. Chittenden D. Sc., i.ssued by the Bureau of 

 Entomology of the United States Department of Agriculture. 



Calpodes etklitts attacks canna plants in the West Indies, 

 but is better known as a pest on account of the injury which 

 it sometimes causes t'o arrowroot, lleferences to this insect 

 have appeared in previous numbers of the Ayricidtural News. 



The larvae protect themselves during the entire larval 

 period by rolling over a portion of the margin of the leaf to 

 form tunnels, within which they live and feed. 



Fig. 1. Moth of the Aekowkoot Worm. 



Attention was attracted by this insect during 1911 

 because of the unusual abundance of its occurrence in several 

 localities in the Eastern States The following information 

 is al:>stracted from the circular mentioned above. 



This insect has been known as a pest of cannas in the 

 United States since 1904, occurring in considerable numbers 

 in certain of the years of this period, and being much less 

 abundant in others. The injury has been the result of the 

 feeding of the larvae, which causes a very ragged appearance 

 of the leaves that detracts greatly from the value of the 

 canna as ornamental plants. 



It has been found that the eggs, which are deposited 

 singly on the surface of the leaf, require from four days in 

 Floiida to six days in Washington, D.C., for hatching. 



The larva moults five times before pupation. The pupa 

 is attached to the leaf by means of a silk band, within the 

 resting place formed by the rolled up leaf margin. 



Many of the eggs are parasitized by Trichogramnia 

 pretiosa. 



The larger canna leaf-roller is a tropical insect, and it is 

 not believed that it can withstand the temperature which 

 prevails during the winter in the latitude of Washington. 

 The attacks in successive seasons depend therefore on the 

 migrations of the adult insects from the more southerly 

 localities in which it occurs. As there are three or four 

 generations in a season, the insect is capable of increasing to 

 considerable number.?, between the advent of spring and the 

 beginning of cold weather. 



The remedies which have been found useful for the 

 control of this insect are hand picking or crushing of the 

 larvae and pupae in the rolltd-up leaves, and the use of 

 arsenical poisons such as I'aris green and arsenate of lead 



applied in the form of sprays. The only objection to the use 

 of these on ornamental plants in parks and garden.*!, is the 

 fear that children may pick the leaves and by putting them 

 in their mouths, suffer from poisoning; but this danger is 

 small. 



A CARBON BISULPHIDE EXPLOSION. 



For several years past carbon bisulphide has been exten- 

 sively used as a fumigant for destroying insects in grain, and 

 in the ground. 



One of the cautions always expressed in connexion with 

 the application of carbon bisulphide refers to its highly 

 inflammable nature, and the likelihood of an explosion if any 

 flame, or even glowing matter, such as that at the end of 

 a lighted cigar, pipe, or cigarette, is brought into contact 

 with the fumes, when these have become mixed with air. 



An article which appeared in the Journal of Economic 

 Entomology, Vol. IV, No. 6, gives an interesting account of 

 an explosion which occurred in Alabama, as a result of apply- 

 ing carbon bisulphide to grain which had been stored while 

 wet, and in which fermentation had commenced. 



The following is an abstract of the article alreadj- men- 

 tioned, which was written by Dr. W. E. Hinds, Entomologist, 

 Alabama Experiment Station. 



In the southern part of Alabama, the black, or rice 

 weevil ((Jalandra oryza) — shown at Fig. 2 — is a serious pest 

 of stored Indian corn, and in order to reduce the seriousness 

 of these attacks, carbon bisulphide is used to a very large 

 extent, and with good results in most instances 



Fig. 2. (a) Or.\nary Weevil; (d) Kick \\::e\ il. 



The farmers in this section believe that by storing the 

 corn with the husk on the ear they reduce the amount of 

 injury by weevils, and, consequently, this is the usual practice. 



In the case under consideration, a large amount of corn, 

 about 1,200 bushels, was collected in one day, when the 

 weather was too wet for cotton-picking, and stored in one mass 

 in a room with a capacity of some 2,400 cubic feet. 



The building in which it was stored was constructed for 

 the purpose, the walls being of concrete, while the partitions 

 and ceilings were made with tongued and grooved boards, 

 forming a very tight enclosure. 



