19 



The larva is dirty white in colour without hairs, cylin drical 

 cut square at the tail end, with a pointed head furnished with 

 two hooks, and is rather more than the third of an inch long. 

 (Fig. 2 6.) 



It continues from 24 to28 days in a larval state, and changes to 

 a chestnut coloured pupa in the ground, and sometimes in 

 the holes of the roots. This is about the fourth of an inch long, 

 barrel shaped, with two thick projections at its lower extremity. 

 (Fig. 2 c.) Pupation continues in the summer season for about 1 16 

 days. There are continuous broods from spring to autumn. 



METHODS OF PREVENTION AND REMEDIES. 



Ammoniacal liquor, which may be had as refuse from gaa 

 works at a low price, has been found to be remedial in some 

 instances. It must be mixed with water at the rate of from 2 

 to 2 1 parts of water to one of the liquor, and poured carefully 

 round the plants so as to get at the roots. 



Ordinary lime water has also been found useful, but the diffi- 

 culty obviously is to get these solutions to the roots. 



Nitrate of soda, soot, and guano put on close round the plants 

 have also been found valuable, as if they fail to act remedial ly 

 they at least stimulate the plant's growth and help it along out 

 of the way of the larvae. 



Badly infested plants should be pulled up and burnt at once, 

 and the soil from which they are taken well limed or gas- 

 limed and dug very deeply. In America strong brine is used 

 occasionally to destroy the larvas in the ground. 



Before plants are put in they should be dipped in solutions of 

 soft soap and quassia, composed of 7 Ibs. of soft soap, 12 Ibs. of 

 quassia, to 100 gallons of water ; or of 7 Ibs. of soft soap and 

 6 to 7 quarts of carbolic acid. 



Hellebore powder has been used for this with some success in 

 the United States, mixed at the rate of a quarter of a pound to 

 10 quarts of water. 



In the United States, according to Professor Lintner, it is 

 dangerous to use fresh farmyard manure for cabbage ground. 



If possible it would be well to avoid taking successive crops of 

 plants of the cabbage tribe on infested land, at least until it has 

 been deeply dug two spits deep, and limed or gas limed. 



