I live in Southern California, and years ago, they began spraying malathion (sp?), to kill the medflys. Anyway, right after that, all the bees and butterflies (all the wimpier creatures) started dying, and the only things you see anymore are wasps, hornets, big huge scary armoured, primitive things. It doesn’t take a brain surgeon to see what happened. They said it would only kill the medflys, but I always thought- how can it do that? Apparently, something went wrong and just nuked all the little critters, except for the Godzilla bugs.
A web search indicates that malathion is highly toxic to bees.
I'm not sure who told you malathion would only kill the Medfly but it can be highly toxic to both bees and flies (includes mosquitoes) especially when aerially applied. I worked in the CA Medfly program in the 1980s.
BTW, what is a Godzilla bug? I found one internet reference to the name as a praying mantis.