INDIRECT INJURIES CAUSED BY INSECTS. 101 



If the beer-drinker be thus interested in the history of these animals, 

 equally so is the drinker of tea. Indeed sugar is an article so universally 

 useful and agreeable, that what concerns the cane that produces it seems 

 to concern every one. This also affords a tempting food to insects. The 

 caterpillar of a white moth, called the borer, for destroying which a gold 

 medal has been long offered by the Society of Arts, is, in this respect, a 

 great nuisance, boring into the centre of the stem, and often destroying a 

 great proportion of the crop. This insect (for his essay on which he 

 received the offered medal) has been described by the Rev. L. Guilding, in 

 the Transactions of the Society of Arts (xlvi. 143.), under the name ofDiatrcea 

 Sacchari, which, however, Mr. Westwood conceives is identical with 

 PhalfEiia saccharalis Fab. 1 An ant also {Formica analis) makes a lodgment 

 in the interior of the sugar-cane in Guinea, and destroys it. Another 

 species of the latter genus does not devour it, and it therefore improperly 

 called Formica saccharivora by Linne ; but, by making its nest for shelter 

 under the roots, so injures the plants that they become unhealthy and un- 

 productive. These insects about seventy years ago appeared in such 

 infinite hosts in the island of Granada, as to put a stop to the cultivation 

 of this plant ; and a reward of 20,000/. was offered to any ane who should 

 discover an effectual mode of destroying them. Their numbers were in- 

 credible. They descended from the hills like torrents, and the plantations, 

 as well as every -path and road for miles, were filled with them. Many 

 domestic quadrupeds perished in consequence of this plague. Rats, mice, 

 and reptiles of every kind became an easy prey to them : and even the 

 birds, which they attacked whenever they alighted on the ground in search 

 of food, were so harassed as to be at length unable to resist them. Streams 

 of water opposed only a temporary obstacle to their progress, the foremost 

 rushing blindly on to certain death, and fresh armies instantly following, 

 till a bank was formed of the carcases of those that were drowned suffi- 

 cient to dam up the waters, and allow the main body to pass over in safety 

 below. Even the all-devouring element of fire was tried in vain. When 

 lighted to arrest their route, they rushed into the blaze in such myriads of 



of entomology. Led by their old prejudices of the fly being produced by cold 

 winds, &c., they do nothing towards its destruction, though if aware of the way in 

 which it is generated (as lately explained), and that by killing each female as it 

 appears early in the spring, they would prevent the birth not of thousands but of 

 millions of aphides ; were they to take measures for thus lessening the number of 

 their destructive enemy, they might in great measure secure themselves from its 

 attacks. The aphides being so soft are killed with the slightest pressure ; so that it 

 is merely necessary to rub an infested leaf between the thumb and fingers, with a 

 force quite insufficient to injure its texture, to destroy every aphis upon it ; and, from 

 expeiiments which I myself made in the hop- grounds of VVorcestershire when at 

 Malvern in 1838, I am persuaded that every leaf of each hop plant might be thus 

 cleared of the female aphides, first attacking it in spring, by women or children 

 mounted on step-ladders for this purpose, in ten minutes or less ; so that six plants 

 being cleared per hour, sixty might be cleared per day at an expense of a shilling 

 for labour, and the first cost of a few step-ladders; and by repeating the operation 

 every week or fortnight, there can be no doubt a hop plantation might be effectually 

 preserved from the fly ; as it might earlier in the spring from the flea (Haltica con- 

 cinna), by shaking them into a kind of wide and deep sieve (divided into two halves 

 with a circular space for the hop poles and hop stems) with a linen bottom and bag 

 for preventing them from jumping out again. 

 1 Westwood, Modern Classif. of Ins. ii. 411. 



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