March 1897.] 



INJUKIOUS INSECTS AND FUNGI. 



391 



attacks of millepedes attracted by the unhealthy state of the 

 roots and by slugs and " pea-bugs," Oniscus. The larvae of the 

 carrot fly often remain in the roots after these have been stored 

 and continue to injure them for some time. 



The carrot fly is well known in Germany. Kiihn says it causes 

 the most common disorder of carrots termed " worm-rot " 

 (Wurmfaule) and the " iron mould " affection. It is also occa- 

 sionally troublesome in France and in other European countries. 

 Kecently it has been noticed in Canada. Schiner states that it 

 infests rape and turnips, and that the flies may be found in 

 numbers in the early spring on the lower branches of bushes 

 and trees in damp situations. 



Life History. 



The carrot fly is shiny black in colour and about the fifth of 

 an inch long, with a wing expanse of nearly half an inch. The 

 wings are iridescent, having dark yellow veins. The head is 

 round, of a reddish yellow colour and very sparingly covered 

 with hairs. The legs are of a light ochreous colour. There is 

 not much difference between the male and female, except that the 

 body of the latter is more pointed than that of the male, and is 

 furnished with a long retractile egg depositor. 



In the early spring the flies appear, and may be seen upon the 

 lower leaves of trees and bushes especially near brooks and 

 streams. When the carrot roots are well established the flies 

 lay eggs upon them just below the ground. All authorities 

 agree that the eggs are laid below the surface of the ground, 

 but none have actually observed how deeply the fly goes down 

 for this purpose. It is believed that it is only just below the 

 surface, and that the larva when hatched goes down instinctively 

 to the lower part of the carrot, as the root is softer there 

 and more easily penetrated. When it has gained a footing the 

 larva works upwards and makes passages, with frequent holes to 

 the outside. The larva is without legs, yellowish white in colour, 

 like parchment, as Bouche says, and nearly a quarter of an 

 inch long. It has no distinct head, but its fore end tapers to a 

 point, in which there are two claw-formed hooks for biting and 

 boring. Before pupating it leaves the root, and, going into the 

 earth, assumes a pupa case of a light brown colour with many 

 wrinkled folds. At the tail end two small black points are seen. 

 The head end is very sloping. 



There are several generations during the summer. Kiihn 

 states that the series of changes is accomplished in between 

 three and four weeks. The pupse of the last generations remain 

 in the earth, and occasionally in the roots, during the winter, 

 and the flies come forth in the first spring days. 



Methods of Prevention and Remedies. 



When it is noticed that the tops of carrots change colour 

 prematurely and become rusty, the roots should be examined, 



