The insect family whose larvae are called 'Flat headed borers' is

The insect family whose larvae are called 'Flat headed borers' is Buprestidae.
Buprestidae is a family of beetles known as jewel beetles or metallic wood-boring beetles because of their glossy iridescent colors. Larvae of this family are known as flatheaded borers.
The elytra of some Buprestidae species have been traditionally used in beetlewing jewellery and decoration in certain countries in Asia, like India, Thailand and Japan.