This is like a vast comprehensive compared with their initial ice cream box primary because I have taken on board fellow-posters' warnings about the larvae getting increasingly voracious and large. I also try to dry the hawthorn with newspaper on wet days such as today, thanks to warnings from other UTM breeders about damping off.
Final point of interest: I did look online for larva breeding boxes of the kind I used as a teenager via Watkins & Doncaster but they are not to be had at the moment. The best websites can offer is the hope of new stocks later in June. Are a lot of us caterpillar breeders about? Martin Wainwright