INDIRECT INJURIES CAUSED BY INSECTS. 135 



necessary for the sustenance of the cattle.^ In many parts of England, 

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

 crops, especially if sown upon clover-lays.^ 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 observa- 

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

 lime applied in much larger doses than usual.^ 



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.'* — 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 of a very important branch of the revenue, the difference in the 

 amount of the duty on hops being often as much as 200,000Z. per annum, 

 more or less, in proportion as ihe fly prevails or the contrary.^ 



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 



• Reaum. v. 11. 



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

 Tipida oleracea and cornicina, which last is very injurious, though not equal 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 brown as if 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. 



3 Stickney's Observations on the Grub. * 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 of entomology. 

 Led by their old prejudices of the fly being produced by cold winds, dec, they do nothing 

 towards its destruction, though if aware of the way in which it is generated (as lately ex- 

 plained), and that by killing each female as it appears early in the spring, they would pre- 

 vent 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 experiments which I myself made in the hop grounds of Worcestershire 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 labor, 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 concinna), 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. 



