144 



notably from the Burton district, where large stores of malt exist. 

 There is little doubt that the presence of this beetle is due to shipments 

 of Indian barley, which, prior to the war, was imported in large 

 quantities for malting purposes. The only Indian barley ever used at 

 the brewery concerned was introduced about four years previously, 

 and the presence of numerous beetles became noticeable two years 

 later. There is now every indication that adaptation to new surround- 

 ings has enabled this species to develop to such proportions as to 

 became a serious economic pest. 



The annual losses to stored wheat in India by this and other beetles 

 became so serious as to lead to an investigation in 1916 [R. A.E., A, 

 V, 126j. Prior to that date nothing whatever was known of the 

 life-history of T. khapra. 



T. khapra measures about 3 mm. in length. The adult, which has 

 a short life of about 10 days, has not been observed directly attacking 

 malt corns. The eggs, averaging 35-40 in number, are deposited 

 in 6-7 days in the furrow, or some other portion of the surface of the 

 grain. After 6-7 days the yellowish-white larvae hatch out. It is 

 during the larval stage that malt and other grains are attacked. The 

 larva begins feeding on loose particles of farinaceous matter, and the 

 exposed endosperm of broken grains, afterwards attacking whole 

 grains by boring through the epidermis. The husk is never eaten. 

 Some 7 or 8 moults occur in this stage. In malt the larva appears to 

 find the strong husk the best protection during moulting, and there is 

 every indication that once inside a grain it never leaves it so long as 

 a particle of the endosperm remains. On breaking open an empty 

 husk, it is usual to find one, two, or even three empty larval skins. 

 The duration of the larval stage in England is not yet known. It is 

 in this stage that infestation is likely to spi-ead. The hairs with which 

 the larva is covered readily anchor it to the clothes of w^orkmen, and 

 for the same reason many individuals would be retained in the meshes 

 of the fabric of an empty sack, and these hibernate until the sack is 

 refilled — perhaps in some other locality. 



Pupation takes place in the last larval skin, which splits, but is not 

 actually cast off. The pupa may be found among the insect debris. 

 Frequently, however, in the case of malt the pupa is found inside the 

 husk, along with previously cast skins ; the adult then escapes from 

 the grain through the hole made by the larva on its entrance. Dead 

 beetles are rarely found inside the hollow grains. 



Barnes and Grove in India [loc. cit.'\ found T. khapra to be the most 

 resistant species of those subjected to the action of various asphyxia- 

 ting agents, even carbon dioxide proving useless from an economic 

 point of view, owing to the ability of T. khapra to enter upon a hiber- 

 nating stage when atmospheric oxygen fails. In any case, there are 

 very serious objections to the use of this gas whenever ungerminated 

 grain is involved. 



In the present case perfect success was obtained by fumigation 

 with chlorine gas, using liquid chlorine as a source, and treatment 

 of the walls, floors, etc., with a hypochlorite solution containing 15 

 per cent, available chlorine. The latter was applied with a sprayer, 

 which ensured penetration into all cracks and interstices likely to 

 harbour the larvae. After treatment the rooms were sealed for a 

 week. 



Such a method of extermination must necessarily be carried out 

 under the supervision of a technical chemist. 



