and should be correct. Also, it is confusing when you want "on" or "onto" sometimes both should be correct.

Another mile long sentence that does not reflect reality. It is like a bunch of words written at random.

what is wrong with 'little'?

I put many little insects etc. Surely that should be accepted.

the option for flies is missing now

As far as I know, butterflies fly, they don't crawl. Oh, well....

A lot of small insects: bees, flies, ants and butterflies. are crawling onto the wall was rejected and is in fact a more correct translation than yours

yes, the correct solution does not include the "and". Actually it rejects the answer with the "and". reported.