100 INDIRECT INJURIES CAUSED BY INSECTS. 



Here also may be included the larva of the long-legged gnat (Tipula 

 oleracea), known in many parts by the name of the grub, which is some- 

 times very prejudicial to the grass in marshy lands, and at others not less 

 so to corn. Reaumur informs us that in Poiton, in certain years, the grass 

 of whole districts has been so destroyed by it, as not to produce the 

 food necessary for the sustenance of the cattle. 1 In many parts of Eng- 

 land, in Holderness particularly, it cuts off a large proportion of the wheat 

 crops, especially if sown upon clover-lays. 2 Reaumur concludes from the 

 observations he made that it lives solely upon earth, and consequently that 

 the injury which it occasions arises from its loosening the roots of corn 

 and grass by burrowing amongst them : but my friend Mr. Stickney, the 

 intelligent author of a treatise upon this insect, is inclined to think from 

 his experiments that it feeds on the roots themselves. However this may 

 be, the evil produced is evident ; and it appears too from the observations 

 of the gentleman last mentioned, that this animal is not killed by lime 

 applied in much larger doses than usual. 3 



Our national beverage, ale, so valuable and heartening to the lower 

 orders, and so infinitely preferable to ardent spirits, is indebted to another 

 vegetable, the hop, for its agreeable conservative bitter. This plant, so 

 precious, has numerous enemies in the Lilliputian world to which I am 

 introducing you. Its roots are subject to the attack of the caterpillar of a 

 singular species of moth (Hepialus Humuli), known to collectors by the 

 name of the ghost, that sometimes does them considerable injury. 4 ; 

 A small beetle, also (Haltica concinna) is particularly destructive to the 

 tender shoots early in the year ; and upon the presence or absence of 

 Aphides, known by the name of the fly, as in the case of peas, the crop of 

 every year depends ; so that the hop-grower is wholly at the mercy of 

 insects. They are the barometer that indicates the rise and fall of his 

 wealth, as well as of a very important branch of the revenue, the difference 

 in the amount of the duty on hops being often as much as 200,000/. per 

 annum, more or less in proportion as the^j/ prevails or the contrary. 5 



ting two alternately, till the whole field of eight acres was gone over. On the fol- 

 lowing morning he employed two women to examine and free from the slugs, which 

 they did into a measure, the tops and slices ; and when cleared, they were laid upon 

 those stetches that had been omitted the day before. It was observed invariably, 

 that in the stetches dressed with the turnips no slugs were to be found upon the 

 wheat or crawling upon the land, though they abounded upon the turnips ; while on 

 the undressed stetches they were to be seen in great numbers both on the wheat and 

 on the land. The quantity of slugs thus collected was near a bushel. Mr. Rodwell 

 is persuaded that by this plan he saved his wheat from essential injury. 



1 Reaum. v. 11. 



2 Two species are confounded under the appellation of the grub, the larvae namely 

 of Tipula oleracea and cornicina, which last is very injurious, though not equally with 

 the first. In the rich district of Sunk Island in Holderness, in the spring of 1813, 

 hundreds of acres of pasture were entirely destroyed by them, being rendered as 

 completely broAvn as it they had suffered a three months' drought, and destitute of 

 all vegetation except that of a few thistles. A square foot of the dead turf being 

 dug up, 210 grubs were counted in it ! and what furnishes a striking proof of the 

 prolific powers of these insects, the next year it was difficult to find a single one. 



5 Stickney 's Observations on the Grub. 



4 De Geer, i. 487. 



5 It would not be difficult to show that nearly the whole of this large sum, and their 

 own still greater losses, are thrown away by the hop planters from their ignorance 



