I went out to check on the hive and found 1 of the 4 has died. There is plenty of honey, pollen and bees, but almost all the bees are piled up on the screened bottom board and against the south side (inside) of the hive. We treated for varroa last fall with Hopguard. We have been checking the debris board below the screened bottom board and have seen around 10-15 mites per week. Last checked the hive last Saturday and while we did not open it up, bees were flying and the hive was humming.

Attached are a couple of pictures. Would appreciate any suggestions. The other three hives appear to be doing great today. Since the dead bees are in the hive, is there anywhere I can send a sample for a disease diagnosis? I live in Missouri but can ship anywhere.

Thanks in advance.