Interesting... when I read your question about 'bug net', I imagined a 'mosquito net' or similar i.e. the kind of thing you'd stretch over your bed in tropical countries as a protective screen. It shows there's a level of ambiguity about what we mean by 'net'. As for what the boy in the picture is holding, I'd call that a 'butterfly net'.

I'd call it an insect net. "Bug" tends to be used more by Americans and is informal language.