Bugs can be removed but it kinda hard. Maybe you can't just removed it with one washing but it can be removed. Just be patient. Auto Detailing Clay of course will remove it permanently. Hope this help!
I use just soap and a sponge with the netting around the sponge. Its the dish scrubbing sponges you can get in the grocery store they really do the job.
Ive never come across a bug that wouldn't come off a bumper before with just a wash mit and soap. But it you have some crazy bugs where you live then a clay bar will most defiantly get it off. But that's not what it was intended for. Its for getting microscopic dirt you cant see off the paint and makes it feel smooth as if it were brand new.