if you killed 40 of em ,you have a huge infestation and thats only the beginning ,sounds like you need your sub floor and roof void powdered,the powder is residual and will do the job ,you could use can spray bombs in the roof and subfloor also and will work ok ,except will leave no residual,and nothing can penetrate the eggs ,thats why you need a residual application like coopex powder.You could kill all the roaches in your house lets say,but in 2 months could be back to square 1 because all the eggs would have hatched,i have did pest control here in australia i know trust me,powder the roof and subloor