Reports to various Correspondents. 71 



The eggs are very minute, oval, white, witli au irregiihir ridged 

 appearance ; they hatch out in about a week, some as soon as four 

 days. Taschenberg states that they take as long as ten days. The 

 maggots which work on and in the roots as previously described are 

 dirty white in colour, fleshy and footless as in all Diptera, tlie 

 segments are provided with rows of minute tubercles by means of 

 which tlie maggots move ; the head end is pointed and provided 

 with two mouth hooks ; the anal end is truncated with ten conical 

 processes, the two ventral central ones being bifid when the grub is 

 full grown, a character which scarcely shows in a young larva; in 

 the centre of this truncated area are the two spiracles, each composed 

 of a brown area with three narrow curved slits ; on each side of the 

 third segment is a fan-shaped spiracle with twelve lobes, which 

 appears to be functionless. When full grown the larva is the fourth 

 of an inch long. This period lasts about three weeks : Slingerland 

 says less than three weeks ; Whitehead, twenty -four to twenty-eight 

 days ; Bouche from tlu'ee to four weeks ; Carpenter, three weeks ; all 

 those I have kept matured within a day or so of the latter date, 

 most in tw^enty-one days. 



As soon as the maggots are mature they leave the roots and enter 

 the soil, and there at a depth of from two to three inches the larval 

 skin hardens and forms a case or puparium (Fig. 9, h) in which the 

 pupal condition is passed. They do not all, however, enter the earth, 

 some pupate in the stems of the cabbages. 



This puparium is at first much the same colour as the larva, but 

 soon turns brown ; it is barrel-shaped in form with two prominent 

 processes in front, the front spiracles are present seen in the maggot 

 and traces of the two bifid spines behind. This stage lasts from two 

 to three weeks in summer, whilst in winter it may last from October 

 to April. There is often to be noticed great variation in size in these 

 puparia. Under favourable circumstances this pest may continue 

 to work all the year round, ibr Dr. Carpenter records the presence 

 of maggots in th(i Xorth of Ireland in January. 



The majority of maggots are matm-e by iSTovember, according to 

 my observation, and have entered the puparium stage in which they 

 pass the winter either in the ground or in the cabbage stalks. In 

 some cases it also seems probable that some of the adult flies 

 hibernate, so that we have this pest passing the winter in three 

 different ways ; but I am not aware of any authentic record of the 

 adult hibernatino-. 



