Count the mites. Beekeepers differ on how to interpret the results. Fewer than 5 mites is a light infestation. Up to 10 mites is a moderate infestation. Over 10 is a serious infestation.
Treatment depends on the number of mites, the time of year and the condition of the hive.
Ten mites before the Spring buildup is not as serious as the same number in the Fall when bees are preparing for Winter. Use rubber gloves when handling any chemical treatment. Test hives in the early Spring before the buildup. If the mite count is high a treatment will help the buildup for Maryland's early nectar flow. If the mite count is moderate, the population buildup for an already strong hive should outpace the varroa.