194 



On the Insects affecting the Turnip Crop. 



deserving of our attention, and in pursuance of this object we will 

 first consider those insects which attack the turnip, a root of the 

 greatest importance to us all : for without turnips our sheep and 

 cattle would be deprived of one great resource, so that we should 

 be almost unable to procure fresh meat in winter, most essential 

 to the health of man ; and the land again would lose that fertility 

 which in feeding off the turnip we secure for the succeeding 

 crops. 



No crop is subject to the attacks of a greaternumber of noxious 

 insects, &c., than the turnip. First, the ants run off with an in- 

 credible quantity of the seeds ; then come two sorts of turnip- 

 fly, the striped and the brassy, which destroy the tender leaves as 

 soon as they burst from the ground ; at the same time we have 

 the maggot of a fly and the wire-worm, both living upon the young 

 roots ; and also a large caterpillar or grub, when they are more 

 advanced ; then follow armies of black caterpillars, reducing the 

 leaves to skeletons, and the blight of the plant-louse, together with 

 a minute moth ; we may add also two wee\ils, which cause the 

 lumps or excrescences on the bulbs ; with slugs, snails, and mil- 

 dew bringing up the rear. 



Before entering upon their history it wdll be necessary to make 

 a few observations relative to the economy of insects, which I beg 

 may be borne in mind in the perusal of these papers^ as they will 

 be of service in the investigations I propose, and in which I hope 

 every practical man will lend me a hand ; they will also smooth 

 the road to those who have not a scientific knowledge of insects, 

 and are not skilled in the study of entomolog}^ 



Insects have been divided into large masses, named orders ; 

 these are subdivided into lesser groups, called families, which 

 comprise smaller companies, designated genera ; and each of 

 these consists of more or fewer species, or different sorts, which 

 occasionally vary in size and colour, and such are termed varie- 

 ties. Another still more important fact to be remembered is, 

 that all insects progress through several stages :* first, the female 

 lays an egg ; this egg hatches and produces, secondly, a larva, 

 which is a little animal called a maggot or gentle, a caterpillar 

 or canker, a worm or grub, &c. Thus w^e have maggots in 

 cheese and meat, called gentles by anglers ; caterpillars on 

 cabbages, cankers in roses, wire-worms and silk-7Vorms, and all 

 sorts of grubs. When any of these have fed until they are full- 

 grown, having been compelled to cast their skins several times as 

 they increase in size, they change, thirdly, to a pupa, chrysalis, 

 aurelia, or nymph : they either enter the earth for this purpose. 



* Plant-lice often bring forth young, instead of laying eggs, and so do 

 blue-bottle flies, but not always ; and there are a few other exceptions. 



