Every cockroach overnight in the entire world grows 50 times their current size. How would this scenario play out? With the attack humans and eat them along with their pets? What kind of destruction would they cause?
They'll all die on their own. Their limbs breaking unable to support their weight. Their body is designed specifically because of it's size. Same with any insect really. Ant's and spider's legs would snap at the sudden weight.
I mean... aside from the destruction their sudden size would cause. They would grow within the walls of buildings/homes etc. That alone could cause... trillions of dollars of damage. Yes... with a T. Because where is there NOT roaches? That would probably be their biggest impact. Just mass... accidental destruction.
There are potential disgusting benefits to starving regions. Look at all that meat. I'm pretty confident we'd still eradicate them... but the world would take quite a while to rebuild. Not to mention the ecological impact. A lot of other creatures needed them for food. With their extinction (by us killing them) who knows what my happen to all kinds of ecosystems.