Yoon, Now is not the time to raise your hands in the air and think about the expense of buying more bees in the future nor be tied to the mast with an albatross around your neck; all is not lost! NOW IS THE TIME FOR IMMEDIATE DAMAGE CONTROL! Yoon, from what you have described, "many underdeveloped bees with shriveled wings, more than what I used to observe under a normal condition, crawl around the grass in front of the hives. I saw one with a varroa attached on the thorax" you have a major case of varroa infestation and it needs to be treated ASAP. I understand that you treated three years ago with Checkmite and have not treated since. FWIW this is my recommendation. First, call your appropriate bee inspector and ask for assistance, you have 50 hives which is a considerable investment of time, sweat, and money. If you are not able to get immediate assistance from either a bee inspector or a very experienced beekeeper then I suggest that you go into every hive, all 50 each yard at a time, and inspect each hive for strength, a viable queen assuring the existance of sparkling white brood in a good pattern, and disease. Next, combine "like" weak and queenless hives; those hives with disease, usually having light tan or brown and dying larvae with a spotty brood pattern, treat with Terramycin and do not combine with disease free hives. If you have brood that is capped and dead and has all indications of American Foulbrood my suggestion, depending upon the amount and intensity of infection, is to either treat for AFB or abate the hive. AFB is indeed treatable if the strain is not resistant to Terramycin and the case has not too far progressed. Sometimes you will need to combine multiple hives in order to assure that you will have numbers - bees- needed for wintering. Frames of pollen and honey from diseased hives need to stay with the same diseased hives. It would be a good idea in this case to treat all of your hives with terramycin as a preventative measure; even if you have no signs of disease - which in cases such as this is unlikely. You will find strong hives, weak hives, and hives in the middle of the road so to speak, take in mind that it is almost October and winter will soon be upon us with cold temperatures and a dearth of nectar and pollen; combine your hives accordingly with that in mind- the season is almost over! Now, after you have combined your hives and treated with terramycin treat for Varroa and trachael mites. Do not be tempted to bypass treatments for your strong hives; treat all remaining hives. Now put an entrance reducer on each hive and wait five days, then repeat terramycin treatments two more times at 5 day intervals. Feed your bees sugar syrup, it will provide food for both brood and winter stores as well as stimulate the queen to lay in greater numbers - going into winter numbers is the goal! Each time you go into the hive give a quick check for viability of the brood, look for sparkling white larvae and fresh eggs in a good pattern. After completion of three terramycin treatments requeen, if you can, those hives that were diseased and overly stressed. Treat for nosema if you wish while you are feeding syrup. Next spring make splits from those hives that were strong and healthy, and you may also consider the purchase a SMR queen for breeding purposes. Yoon, we have watched your progress as you have posted on this List; and I believe that we are all wishing for the best to come about of your Varroa problem. It is my opinion to take immediate corrective action, save your bees, and don't give up the ship! Let us know how you are progressing. I wish you well! Chuck Norton Norton's Nut & Honey Farm Reidsville, NC USA :::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::: -- Visit www.honeybeeworld.com/BEE-L for rules, FAQ and other info --- ::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::