| Abstrakt: |
Observations on the field activity of Hylemya brassicae (Bouché) were made in relation to their natural location, attraction to baited traps, emergence from soil, and damage to a host crop of various stand densities. Adults were located more abundantly in or near cruciferous plantings than in other types or places of shelter and similarly were attracted more to traps baited with cruciferous plants than to those with onion culls (most onion maggots), meat meal (most seed-corn maggots), or nothing. In the spring, adult cabbage maggot flies emerged in progressively fewer days from undisturbed soil as the levels of the puparia ranged from 12 inches to the surface. Emergence from puparia 4 inches under loose soil was the most rapid of all, probably because of a higher temperature in this less-compacted soil. As the number of turnip roots increased from 5 to 30 per foot, the number of maggot feeding tunnels per foot of row progressively increased from 8 to 12, but tunnels per 10 roots decreased from 16 to 4. |
