Many people have been reporting dead hives this winter, often at a loss as to what exactly went wrong. One club member discovered a dead hive with 30lbs of honey still in it. Another, who keeps two hives every year, also loses two every winter. She thinks her problem is location -- living in town might expose her bees to more pollutants than they can handle.
If you lose hives this winter and just can't figure out why but want to go beyond speculation, a great option is to send a sample of dead bees to:
Bee Disease Diagnosis
Bee Research Laboratory
Bldg. 476 Room 20
Beltsville Agricultural Research Center - East
Beltsville, MD 20705
To prepare the sample, collect about 100 of the sick bees in rubbing alcohol. Let them soak overnight. Drain off the alcohol, then put them in a ziplock bag. Put the bag in a small cardboard box so the samples won't get crushed. Mark the box with your NAME, ADDRESS, & BRIEF DESCRIPTION OF THE PROBLEM so they know where to send the results.
Best of luck!