Hm.. these ants are really interesting, because they have 4 worker castes- smallest caste- minor, medium caste, majors and submajors. The queen is about 14-15mm long, submajor is about 1cm. Like each Messor specie, these ants don´t like shaking and especially queen is sensitive for it! Bird seeds are good choice, they will like them

I have very good experience with them, not big but I never had any problems, but don´t forget that they really don´t like shaking

And good luck with them!
and... they chew seeds and I saw, like they chew ,,ant bread" from it. It is somethink like small ,,ball" from chewed seeds, and usually about 3 and more workers chewing it together, by my observing....