Cabbage butterfly update

cwbdecoy Cabbage white butterflies have had a lovely time with my broccoli this year. There are several conditions that make brassicas very attractive to these pests and the brown cabbage moth. See Cabbage white butterfly.
My problem was that I inadvertently added some very alkaline compost to that area of the garden, (See recent post on Compost pH) and it is taking a while for the soil to get back to a neutral pH.

After spending a week or so removing eggs, squashing tiny caterpillars, or feeding larger ones to the chooks, I remembered a tip someone gave me long ago to deter these pests but have not needed to use before. The tip was to slip the plastic clips that seal loaves of sliced bread onto the edge of some of the Brassica leaves. White seals to deter the C W butterfly and beige ones for cabbage moth. The theory being that the adult butterflies and moths will “think” that eggs are already being laid on these plants and they look for another food source for their larvae.
My broccoli plants are looking healthier already and I have not found any more eggs under the leaves, but I don’t know if the seals are working or the pests are no longer present in our area. Has anyone else tried this tip?

The cabbage family

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This family, called the Brassicas, tend to be more susceptible to attack from the Cabbage Moth and the Cabbage White Butterfly when conditions are too warm for them or when the soil they are growing in is too acid for their liking, especially while the plants are young.
The cabbage family includes Brussels sprouts, Chinese cabbage, cauliflower, horseradish, kale, kohlrabi, mizuna, mustard greens, swede, tatsoi, turnip, watercress and stock, and is also related to radish. These plants need both boron and molybdenum for healthy growth and these are only available to plants when the soil pH is close to neutral. If you know that your soil is acid, and your Brassica plants are being attacked, give the bed a drink of dolomite or agricultural lime. Dissolve a generous handful in a full watering can and apply this to each square metre of the bed. Repeat the application if pests are still hanging around in two weeks.
In the meantime, remove all pest eggs from under leaves and leave crushed caterpillars on the leaves. This helps to deter further egg laying.