Somehow, we managed to get some serious pesky critters in our broccoli beds. We hardly ever have anything like this and it took us awhile to catch on what was happening... They are: Cabbage Maggot, Diptera: Anthomyiidae, Delia radicum (L.). They're just starting and we dug up all we could find and I'm making a BD spray out of the larvae and pupae. Do I have to wait until they dissolve? Can I speed this up by mushing them up? I hate mushing up larvae! We're going to dig in some diatomaceous earth too. The ones that have already pupated that we can't find will be the second generation. Whoopee!
Is there any other measure we can take? The literature says that we're out of luck if we can see the larvae eating away on the roots. The Extension agent says they overwinter here in the roots of wild mustard. The only thing we did differently than we usually do is get manure for next year earlier than usual and it's been cold and wet. I bet we brought them in there and the flies hatched out and flew to the brassicas. IDENTIFICATION: The adult stage of the cabbage and seedcorn maggots is a small (about 1/4 inch long), dark-grey fly that is similar in appearance to the house fly. The legless larvae of both species are white, tapered maggots that reach a size of about 1/3 inch long when fully grown. Maggots of these species are virtually indistinguishable from one another in the field. LIFE HISTORY: Cabbage and seedcorn maggot adults typically emerge in April and begin laying eggs. Female cabbage maggot flies actively seek out and lay eggs on the lower portions of stems of young host seedlings or in nearby cracks in the soil. Within a few days the eggs hatch and the tiny maggots burrow down to the roots and begin feeding. About three to four weeks later pupation occurs in the soil which is followed about a week later by the emergence of second generation adults. Several generations may occur as late as early July, but the first generation is the most destructive. Soil-borne pupae of the last generation serve as the overwintering stage. The life cycle of the seedcorn maggot is similar to that of the cabbage maggot; however, the seedcorn maggot prefers to lay eggs in freshly-tilled soil that is high in moisture and organic matter, and especially in soil where animal manure has been applied because it is highly attractive to female seedcorn maggot flies during egg laying. The eggs of the seedcorn maggot hatch within a few days and the maggots begin feeding on decaying organic matter or the germinating seeds of wild or crop plants. Seedcorn maggots are known to be highly attracted to odors produced by germinating seeds. CONTROL: No action thresholds or scouting techniques currently are available for cabbage or seedcorn maggots, thus control measures typically rely on preventive use of soil-applied granular insecticides or insecticidal seed treatments at planting. Ground beetles and other predators may provide some degree of control, but serious damage can occur if conditions after planting are cool and wet. Mechanical barriers such as tar paper, plastic mulch, and foam-rubber collars placed at the base of plants have been used with some success to prevent egg laying by cabbage maggots; however, insecticidal seed treatments or the more expensive granular insecticides, when used at planting, are considered the best methods for controlling seedcorn maggots. Because subsequent generations of seedcorn maggots are not as damaging, replanting usually is effective, although costly. Also, gardens with a history of seedcorn maggot problems may benefit from the application of an insecticidal seed treatment at planting. * * * * * Screen cones or a mesh netting over early spring cabbage prevent the cabbage maggot fly from laying its eggs at the base of the plant. _______________________________________________ BDNow mailing list [EMAIL PROTECTED] You can unsubscribe or change your options at: http://lists.envirolink.org/mailman/listinfo/bdnow
