ENTOMOLOGY 153 



It is not consistently present in our fields. Some seasons it 

 appears in scattered localities and occasions a good deal of complaint. 

 Then it disappears and nothing is heard of it for a number of years. 

 It seems not to endure very severe winter weather, being a southern 

 insect, and this may account for its comings and goings. (Bui. 

 114, Ky. Agr. Exp. Sta.) 



Black Swallow-Tail Butterfly. There may often be found feed- 

 ing on the foliage of carrots and parsnips a handsome velvety green 

 caterpillar ornamented with bands of yellow. This is the larva of 

 one of our largest and most beautiful butterflies, black in color, or- 

 namented with rows of bright yellow spots. The caterpillars do not 

 feed, in colonies and consequently are not often injurious, the 

 amount of foliage consumed by an individual seldom affecting the 

 vitality of a plant. Being conspicuous, they may, if sufficiently 

 numerous to require repression, be picked off by hand and crushed 

 under foot. They are kept in check, however, by a large parasitic 

 fly, which lays an egg on a caterpillar from which hatches out a 

 grub that feeds within the body of its host until the chrysalis is 

 formed, and then completes its work of devouring all that remains, 

 a fly with four clear membranous wings coming out instead of the 

 butterfly. 



Carrot Rust-Fly. This is a more serious enemy to the plant 

 than the preceding species. It is a comparatively recent importation 

 from Europe, having been first observed in this country about twen- 

 ty-five years ago. Its attack may first be noticed in spring when the 

 leaves of young carrots turn reddish, and on examination the roots 

 will be found covered with rusty blotches, hence the name of the in- 

 sect. The parent of the mischief is a small two-winged fly, one- 

 quarter of an inch long, with dark green body, head and legs palft 

 yellow and the eyes red. From the eggs, which are laid on the 

 stem below the surface of the ground, the young maggots make their 

 way into the root, and tear the tissues in a similar manner to the 

 cabbage maggot described above ; the attack causes the rusty blotches 

 to appear. The maggots of a later brood infest the full-grown roots 

 and continue their work of destruction in the root-house during the 

 winter. Celery and parsnips are also attacked. 



Preventive measures seem to be the only remedies available. 

 To deter the fly from laying her eggs, the rows of young carrots, 

 when ready for thinning out, should be" sprayed 1 with kerosene emul- 

 sion, or dusted with sand or plaster in which coal-oil is mixed, half a 

 pint being used to a pailful of the material. The application should 

 be made weekly, and especially after hoeing, until about the middle 

 of July. 



In gardens where carrots are grown for table use and size is not 

 an object, late sowing is found to be advantageous; the plants thus 

 escaping the egg-laying of the fly. Repeated sowings a week or so 

 apart, will secure the freedom of some of the crops from attack. The 

 plants should not be grown two years running in the same piece of 

 ground. Stored roots, if found affected in the winter, may be treated 



