Q: These bugs are savagely attacking our turnips and other leafy vegetables. What are they and how do you get rid of them?
A: They are grubs of the yellowmargined leaf beetle. The adult beetle has an edge of yellow on its hard wing covers. Both the grubs and the adult beetles feed on collards, turnip greens and cabbage.
If you are persistent in your home garden you can spot the yellow eggs on the backside of leaves and mash them when seen. The same fate should befall the grubs, which often feed in a small group.
I don’t know of an effective organic insecticide but the grubs and adults can be controlled with acetamiprid ( Ortho Fruit and Vegetable Insecticide)