Getting Rid of No-see-ums?

I live in Philadelphia and these little monsters (midges or no-see-ums) are driving me crazy. I went to the psych ward for 10 days. I know the property management sent in an exterminator. So everything was good when I came back home. Now they seem to be starting to come back again. Please tell me what to do to kill them once and for all. I'm desperate!

Help!