Found eggs,big small looking like magots and brown ones all sizes,looks like they eaten wood away in places,used household flea spray what are they and will it kill them all of?so far its killing them

Its eaten little bits of wood,look like brown thing all diffrant sizes some look like magots,inside of leather sofa,have ripted linning out underneath hoovered them and sprayed flea spray which is killing them off do I carry on using it?and what are they?I live above the rottest house in England could that come from them?