[Kristen]

TBH it's easier just to pick/wash off the caterpillars when they appear. The trick is to catch them early by careful inspection on a regular basis once you see the butterflys.

I've done that in the past (before I used netting) and I just rubbed the eggs off the bottom of the leaves before they became caterpillars

On that point: I wonder how long one has, between laying-and-hatching?  Might be long enough that even somewhat infrequent visits to the Lotty would be often enough?

Won't help with pigeons, in Winter, though

[Kristen]

I wonder how long one has, between laying-and-hatching?  Might be long enough that even somewhat infrequent visits to the Lotty would be often enough?

"The length of time it takes for the eggs to hatch depends on the temperature. Most eggs hatch four to eight days after being deposited on the host plant"
http://animals.pawnation.com/life-cycle-cabbage-white-butterfly-4168.html

So visiting the Lotty twice a week would be enough ...