320 THE TUENIP CROP. 



and, according to the amount of injury these sustain, is the 

 vigour and the life of the young plant determined. If it 

 has power enough to throw out a second pair of leaves, it 

 in general gets over the injury, as its growth at this period 

 is very rapid, and it is better able to withstand the dimi- 

 nishing attack of its enemy. An allied species, slightly 

 differing in appearance, the H. concinna, is also met 

 with, attacking the young plant. At an early stage of 

 their growth, the wire worms and " surface-grubs" (belong- 

 ing to the genus Mamestra) frequently commit serious 

 ravages by eating through the incipient root-stalks or 

 bulbs, and thus either destroy the plant or check its after- 

 development. As the growth advances, a member of the 

 "weevil" family Ceutorhynchus contractus finds a sup- 

 ply of food in the leaves of the plant, which it commences 

 to devour, and at the same time makes use of the root as 

 a receptacle for its eggs, which, after having punctured 

 the cuticle, are deposited therein. Some entomologists 

 (Drs. Fleming and Calvert) tell us that the turnip suffers 

 as much from this insect as from the "fly/' No sooner 

 has it passed through this stage of its career than another 

 enemy appears, in the shape of the " black nigger" Atha- 

 lia spinarum a voracious caterpillar of the "saw-fly" 

 genus (Tenthredinse) which in some seasons speedily dis- 

 poses of the entire leaves of entire crops. This last season 

 (1859) its ravages were witnessed in a very marked degree- 

 In its absence, the work of defoliation is always more or 

 less attended to by the ordinary caterpillars of the cabbage 

 and turnip butterflies Pontia brassicce and P. rapce 

 which are to be seen every year in the gardens and fields 

 of every part of the country, and always feeding on some 

 portion of our cultivated plants. About the month of 

 August, when the plants which have escaped injury from 

 the foregoing insect attacks have well developed their 

 tops, and assumed a vigorous appearance, the leaves ex- 



