INDIRECT INJURIES CAUSED BY INSECTS. 107 



to turn black as if sprinkled with soot ; and the nutriment being subtracted 

 from the pods by their constant suction, they are prevented from coming 

 to their proper size or perfection. The beans also which they contain are 

 sometimes devoured by the caterpillar of a small moth. 1 Onions, which 

 add a relish to the poor man's crusts and cheese, and form so material an 

 ingredient in the most savoury dishes of the rich, are also the favourite food 

 of the maggot of a fly, that often does considerable damage to the crop. 

 From this maggot (for a supply of onions containing which I have to thank 

 my friend Mr. Campbell, surgeon of Hedon, near Hull, where it is very 

 injurious, particularly in light soils) I have succeeded in breeding the fly, 

 which proves of that tribe of the Linnean genus Musca, now called An- 

 thomyia. Being apparently undescribed, and new to my valued corre- 

 spondent Count Hoffmansegg, to whom I sent it, I call it A. Ceparum. 

 The diuretic asparagus, towards the close of the season, is sometimes ren- 

 dered unpalatable by the numerous eggs of the asparagus beetle (Gfioceri* 

 Asparagi), and its larvae feed upon the foliage after the heads branch out. 

 Cucumbers with us enjoy an immunity from insect assailants; but in 

 America they are deprived of this privilege, an unascertained species, 

 called there the cucumber fly, doing them great injury. 2 The plants of 

 spinach are sometimes eaten bare by the blackish-brown caterpillars of the 

 lovely little moth Glyphypteryx Rcesella. 3 Horse-radish (as well as the 

 cabbage tribe) is attacked by the larvae of another moth, Mcsographe for- 

 ficalis.* And to name no more, mushrooms, which are frequently culti- 

 vated and much in request, often swarm with the maggots of various 

 Diptera and Coleoptera. 



The insects just enumerated are partial in their attacks, confining them- 

 selves to one or two kinds of our pulse or other vegetables. But there 

 are others that devour more indiscriminately the produce of our gardens ; 

 and of these in certain seasons and countries we have no greater and more 

 universal enemy than the caterpillar of a moth called by entomologists 

 Plusia Gamma, from its having a character inscribed in gold on its primary 

 wings, which resembles that Greek letter. This creature affords a preg- 

 nant instance of the power of Providence to let loose an animal to the 

 work of destruction and punishment. Though common with us, it is 

 seldom the cause of more than trivial injury ; but in the year 1735 it was 

 so incredibly multiplied in France as to infest the whole country. On the 

 great roads, wherever you cast your eyes, you might see vast numbers 

 traversing them in all directions to pass from field to field ; but their 

 ravages were particularly felt in the kitchen-gardens, where they devoured 

 every thing, whether pulse or pot-herbs, so that nothing was left besides 

 the stalks and veins of the leaves. The credulous multitude thought they 

 were poisonous, report affirming that in some instances the eating of them 

 had been followed by baneful effects. In consequence of this alarming 

 idea, herbs were banished for several weeks from the soups of Paris. For- 

 tunately these destroyers did not meddle with the corn, or famine would 

 have followed in their train. Reaumur has proved that a single pair of 

 these insects might in one season produce 80,000 ; so that were the 

 friendly Ichneumons removed, to which the mercy of Heaven has given it 



1 Reaum. ii. 479. 2 Barton in Philos. Magaz. ix. 62. 



3 Kollar's 7ns. inf. to Gardeners, &c. p. 157. * Ibid. p. 155. 



