no capped brood for several weeks

[Rodmo1]

I just got back from inspecting my hives and found that one hive in particular has VERY little capped brood. It is an overwintered hive with a new queen about 6 weeks ago. I first noticed this problem several weeks ago and just thought the queen had a late start in laying. Today, however, there should have been plenty of capped brood as there was lots of larva last week. What could cause a hive to do this? Just to be safe I treated with thymol today in case of mites.

[Rodmo1]

Is it possible that bees would kill off the brood once it is capped. Aside from the lack of capped brood there has always been plenty of eggs and larva.

[Fl_Beak]

How is the 'population?'

[Rodmo1]

The population is less then it should be...seems to be staying somewhat constant. The hive seems to have almost no foragers.