[Jim the builder]

Hi, Jim here (again), with a new problem for all you more experianced gardeners. I am in the process of constructing a brasica cage to keep the butterflies off me sprouts and other brasicas. However, I was curious if anybody knows a way that whiel keeping the butterflies out I could let other insects in! I am intending to use debris netting which has very fine holes.

[grinling]

You don't need to let other insects in.
I do winter patch and everything else patch. Snow causes probs with winter roof, so would need to desnow before it breaks.
I use debris netting which another allotmenter gave me. Thicker poles needed as it is heavy. Not many weeds grew.

[mumofstig]

debris netting lets aphids in.
You need netting with less than 7mm to keep the butterflies out, but I'm hoping that the ladybirds will get through that size to eat the aphids 

[Kleftiwallah]

Try pond guage mesh, it is far more robust than pea/bean type stuff.     Cheers,   Tony.