Fig. 10.—Ephestia kühniella. Moth-infested biscuit.
Together with these derelict biscuits were certain long metallic coils and other apparatus used in investigating certain phases of the life-history of the moth and the manufacture of the biscuit. The exhibit illustrates an article which had recently appeared on the Baking of Army Biscuits, by Mr. Durrant and Lieut.-Colonel Beveridge, on the ‘biscuit-moth’ (Ephestia kühniella), a member of the family Pyralidae. The article recorded their efforts to arrive at a means of checking this very serious pest to service stores.[6]
The biscuit-moth (E. kühniella) was described two years before its larva had been noted damaging flour at Halle. There has always been a certain amount of international courtesy in attributing the provenance of insect pests to other countries; and when E. kühniella began, about ten years later, to attract attention in England it was believed to have been introduced from the United States, via the Mediterranean ports, in American meal. The American origin was, however, denied by Professor Riley, who, in a letter to Miss Ormerod, states, ‘I think I can safely say that this species does not occur in the United States.’ At the moment of writing these words Professor Riley was in the act of packing-up to leave Washington for Paris. Possibly he was excited, certainly he was inaccurate, for the species was then known to be prevalent in Alabama, North Carolina, and other States. In fact, to-day it is recorded throughout Central America and the Southern States, and in most of the temperate regions of the New World.
Fig. 11.—Ephestia kühniella. × 2.
The moth itself is a rather insignificant, small insect, of a slatey-grey colour. Its eggs, rather irregular ovoids, are laid upon the biscuit into which the issuing larvae bore. These latter are soft and like most creatures which live in the dark, whitish, though with a tinge of pink; the head, however, is brown and hardened. The larva is constantly spinning silken webs or tissues, which in the most untidy way envelop the biscuit. It finally entombs itself in a whitish silken cocoon, and herein it ultimately turns into a chrysalis or pupa.
Another Pyralid moth—Corcyra cephalonica—makes similar unpleasant webs all over biscuits, rice, or almost any farinaceous food; but, since its larvae are unable to live unless there be a certain degree of moisture in its food, it is less injurious to baked food than the Ephestia, for whose larvae nothing can be too dry. Corcyra seems originally to be a pest of rice, and to have been introduced into Europe with Rangoon rice; but it readily alters its diet in new surroundings, and will live on almost any starchy stuff, if not too desiccated.
The problem that Lieut.-Colonel Beveridge and Mr. Durrant, of the British Museum, set out to solve was at what stage in the manufacture of the Army biscuits does our soldiers’ food become infested, and whether any steps could be taken to avoid or minimise such infestation.
