Lawson on Aphis Avence, 265 



sents a formidable appearance on account of the vastness of its 

 numbers. In some fields, a few days after its first appearance, 

 the ears of grain became covered with it; in fact the wheat was 

 commonly spoken of as " dark with it." The fly presented itself 

 chiefly in the wingless form, the individuals clustering in great 

 numbers in the upper parts of the culms and panicles of wheat, 

 rye, oats and barley, and this season they have been observed on 

 Indian corn and various other grasses. Most of them are station- 

 ary, but some are usually moving about with a rather awkward 

 motion resembling that of mites under a magnifying glass. On 

 each panicle or head of grain they are found to be of various sizes, 

 according to age, some scarcely large enough to be visible to the 

 naked eye, others as large as the capital letters on this printed 

 page. They vary in colour ; some are pale apple-green, some of 

 a brownish yellow colour, and many, especially the older and 

 larger ones, are of a rather deep brick-red colour, when they be- 

 come very conspicuous. In some cases where the whole ears 

 were covered with the insects, the total destruction of the crops 

 seemed to some of the farmers to be inevitable. They looked 

 upon the ** new bug plague " (for everything that looks like an 

 insect is called a bug) as the greatest calamity that had ever be- 

 fallen our fields. It was deemed advisable therefore to publish 

 in the Kingston newspapers an account of the habits of the insect* 

 with the view of allaying unnecessary fears. Attention was drawn 

 to the following among other facts : — The aphides do not gnaw 

 the plant's stem and leaves like caterpillars, nor like the wheat 

 midge, injuriously afi'ect the young grain, but simply suck the 

 juices of the exposed parts of the plant. The plant necessarily 

 8uff"ers from this injury, its energies are weakened, the leaves 

 and other parts shrivel and blister, and an inroad is formed for 

 other diseases ; but, while aphides are highly injurious to thin 

 and succulent leaved plants, the compact tissue of wheat and 

 other grains, hardened too by silica, is not so liable to suflfer and 

 become deformed, and a vigorous healthy crop of grain will hard- 

 ly be injured. No doubt the yield is lessened by the presence of 

 the insect in vast numbers, and the quality of the grain perhaps 

 slightly deteriorated, but the injurious efi'ects are by no means 

 so extensive as the formidable appearance of the insects would in- 

 dicate. 



In Britain the bean crop is annually liable to the attacks of an 

 allied black species (Aphis JRumicis) which appears in such nam- 



