Davus sp. Behavior

I have both Davus Pentaloris and Davus sp. Panama slings and I am a little worried about them. I have had them for over a month and I have gotten them both to feed and molt. However, they both borrow and basically plug up the holes to their burrows. Most of my fossorial Ts will have an entrance to their burrows and will come and grab their prey items out of their holes.the last few times i have attempted to feed them I have put meal worms with their heads crushed in their vials but they haven't unearthed themselves in order to feed. What would you guys reccomend as far as feeding techniques are concerned? I really want to grow these tarantulas up!