128 INDIRECT INJURIES CAUSED BY INSECTS. 



of Geocorisa Latr. ; but it seems very difficult to copceive how an insect 

 that lives by suction, and has no mandibles, could destroy these plants so 

 totally. 



When the wheat blossoms, another marauder, to which Mr. Marsham 

 first called the attention of the public, takes its turn to make an attack 

 upon it, under the form of an orange-colored gnat, which introducing its 

 long retractile ovipositor into the centre of the corolla, there deposits its 

 eggs. These being hatched, the larvae, perhaps by eating the pollen, 

 prevent the impregnation of the grain, and thus in some seasons destroy 

 the twentieth part of the crop.^ 



Much mischief is also sometimes done by a species of Thrips (T. cere- 

 atina Haliday), a minute insect, often abundant on flowers, which, insinu- 

 ating itself between the internal valve of the corolla and the grain, inserts 

 hs rostrum into this last, and causes it to shriveP ; and according to Vas- 

 sali Eandi^, as quoted by Mr. Haliday, the same species also attacks the 

 stem at a still earlier period, causing the abortion of the ears, and some- 

 times to such an extent that in 1805 (in which year the wheat in Eng- 

 land, also, suffered apparently from this cause) one third of the wheat 

 crop on the richest plains of Piedmont was destroyed by this seemingly 

 insignificant little insect."* 



One would think, when laid up in the barn or in the granary, that wheat 

 would be secure from injury ; but even there the weevil (^Caladra grana- 

 rid), in its imago as well as in its larva state, devours it ; and sometimes 

 this pest becomes so infinitely numerous, that a sensible man, engaged in 

 the brewing trade, once told me, speaking perhaps rather hyperbolically, 

 that they collected and destroyed them by bushels ; and no wonder, for 

 a single pair of these destroyers may produce in one year above 6000 

 descendants. There are three other insects that attack the stored wheat, 

 which are more injurious to it than even the weevil. One is a minute 

 species of moth (7Vnca granella L.), of which Leeuwenhoek has given 

 us a full history under the name of the wolf. Another is a species of the 

 same genus, at present not named, which, as we are informed by Du 

 Hamel,at one time committed dreadful ravages in the province of Angou- 

 mois in France. The third is Trogosita caraboidcs, a kind of beetle, 

 the grub of which, called CadeU€,0\\v'ier tells us did more damage to the 

 housed grain in the southern provinces of France than either the weevil 

 or the wolf.^ 



In this place, too, must be noticed the caterpillars of a moth (Carflr- 

 drina cubicularis), which Mr. Raddon told me were found in such quan- 

 tities in a wheat-stack near Bristol, when taken down to be thrashed, that 

 he could have gathered them up by handfuls, and they had done much 

 injury to the grain.^ 



Here I may just mention a few other insects which devour grains that 

 are the food of man, concerning which I have collected no other facts. 

 The rice-weevil (^Calandra oryza) is very injurious to the useful grain 

 after which it is named ; as is likewise another small beetle, Lycius den- 



' Tipnla tritici K., belonging to Latreille's genus Cecidomyia. — Marsham and Kirby in 

 Unn. Trans, iii. 242—245. iv. 225—239. v. 'JG— 110. 



• Kirby in Linn. Trans, iii. 242. 3 ^(f^ Acad. Turin, xvi. lixvi. 



• Haliday in Entom. Mag. v. 444. » Oliv. ii, n. 19. 3, 4. 



• Trans. Ent. Soc. Lond. ii. proc. xlii. 



