Five little caterpillars

We have had a delightful flight of large white butterflies recently, far more than last year which is encouraging.
I am trying to have a successful purple sprouting broccoli crop next spring and so I didn’t want the caterpillars all over it, and netted it. Instead, I planted them some nasturtiums which are second best in the opinion of the egg layers. However they seem to be very satisfactory for the caterpillars!
I have no idea why they have lined up like this, it will be interesting to see what they are doing tomorrow. I hope they are not planning to migrate to my cabbage patch!!