And the fleece must be tight to the ground.
A problem - it's so late in the season that most eggs will be laid by now - meaning that, if you cover the veg, the caterpillars will do their thing out of your sight. My only recommendation now is to do a daily squidge of eggs & caterpillars. If you want to spray, there is a safe product called Dipel. This will kill all wigglies in minutes.
"The crystals are aggregates of a large protein (about 130-140 kDa) that is actually a protoxin - it must be activated before it has any effect. The crystal protein is highly insoluble in normal conditions, so it is entirely safe to humans, higher animals and most insects. However, it is solubilised in reducing conditions of high pH (above about pH 9.5) - the conditions commonly found in the mid-gut of lepidopteran larvae. For this reason, Bt is a highly specific insecticidal agent." = Tim
