Looks like a monarch to me and yes they are toxic. I don't know for sure but it's probably a good idea not too feed unless you are 100% sure of the species. As a rule it's best to stay away from any brightly coloured insects, as in nature it usually signifies poison.
I'll usually only feed moths and grasshoppers from the wild (pesticide free area) since they are easy to identify.
It's not a monarch. It's more brownish. I'm not going to feed him unless I can find out exactly what he is. We have these bright blue ones also but I know bright equals toxic or a bad taste. Thanks for trying to identify.