Insect pests of food ; the control of insects in flour mills / [by J. A. Freeman and E. E. Turtle] ; with a foreword by the Director of Infestation Control.

  • Great Britain. Ministry of Food.
Date:
1947
Catalogue details

Licence: Public Domain Mark

Credit: Insect pests of food ; the control of insects in flour mills / [by J. A. Freeman and E. E. Turtle] ; with a foreword by the Director of Infestation Control. Source: Wellcome Collection.

    10/98 (page 2)
    Ephestia kiihmella. Although we have a fair body of knowledge about the biology of many of the stored products pests it is unsound to assume that a tropical pest will not establish itself in this country. Many kinds of insects and mites are constantly being introduced and amongst the introductions may be races which are adapted to life in temperate conditions or the introductions may survive in locally favourable situations such as heated buildings. As an example of the rapid spread of an insect originally of a very local distribution one may cite the mill moth, Lphestia kiihniella. It was first discovered in 1877 in a mill in Saxony and was recorded in certain places during subsequent years as follows :— Lower Rhine and Belgium 1884, England 1886, ‘Trieste 1887, Canada 1889, South ' Africa 1890, Venezuela 1891, California and Jamaica 1892, Sweden 1894, New York and N. Carolina 1894, Pennsylvania 1898, Wisconsin 1899, Minnesota 1910. It is now found all over the world and represents a problem to every flour miller. The spread of this insect seems to be closely correlated with the development of roller flour milling and international trade in milling products. It is clear that much of the damage has already occurred by the time the wheat reaches the mills in this country, but the loss has to be borne somewhere and, over a long period, it is the consumer who suffers. It should be the aim to ensure that no further losses occur which could be avoided by careful attention to infestation control in the course of the milling operations. The losses which are liable to occur in the milling industry as the result of insect and mite infestation may be broadly classified as damage to wheat ; interference with productive processes ; contamination and spoiling of finished products ; loss of goodwill and trade reputation. Wheat which arrives at the mill in an infested condition may continue to deteriorate during storage and not only will actual loss in weight result from feeding by insects but the wheat may heat, become musty or mouldy and unsuitable for milling. Wheat which arrives heavily infested by mites may be tainted and require special treatment before it can be milled. It may be difficult to produce a satisfactory high extraction flour from badly “ weevilled > wheat owing to the high proportion of endosperm destroyed by the insects. In the same way flour produced from wheat whose germ has been damaged or eaten by mites, flat grain beetles (Laemophloeus sp.) or cacao moth caterpillars (Ephestia elutella) is likely to contain less of the valuable germ constituents than flour made from sound wheat (Plate 1). Within the mill there is interference with production principally owing to the webbing produced by the caterpillars of the mill moth. If this webbing is not re- moved regularly it is liable to cause chokes in spouts and reduce the sifting capacity of reels and of machines by covering the screening surfaces. Other insects such as the cadelle (Tenebroides mauritanicus) and the larder beetle (Dermestes lardarius) may bore into the woodwork of machines and the former, in particular, is known to bite holes in silk covers, thus reducing the efficiency of separation of stocks. It can be readily demonstrated that flour will contain the eggs, and sometimes the adults and larvae, of insects living in the milling machinery and there is little doubt that mites can survive the whole process of milling. Although the screens used for the final stages of the production of high grade flour are adequate to exclude even the eggs of some species, this is no sure protection because quite heavy infestations of the mill moth have been observed in the packing bins and hoppers. The first stage in the protection of the finished products is, therefore, to control infestation in the machinery, but the use of non-infested bags is also of high importance. As is stated elsewhere in this pamphlet, the returned flour bags represent one of the principal sources of infestation of mills. The treatments commonly in use for the cleaning of bags are