Monday, May 20, 2013
On sunny days in January and February, when the temperature is 40 or above beekeepers have been opening up the tops of their hives to check on honey reserves and see if they need feeding. Unfortunately, some beekeepers are finding dead hives. Sadly, I am one such beekeeper who experienced this a couple weeks ago.
After overcoming the shock and disappointment of losing a hive, I contacted the state’s bee inspector Tony Jadczak, who came over and went through my hives. What he found in the hive, that had been my strongest last summer, were dead bees with stunted abdomens and deformed wings. Upon examination of the lower hive body, he found combs with partially emerged bees (heads exposed with tongues extended) visible. Classic signs of Varroa Collapse (a significant Varroa mite infestation).
Varroa mites are a very serious problem for new and experienced beekeepers in the United States and most other parts of the world. They can kill your bees, even in the first year, if you do not manage the level of infestation. The mites feed on developing larva and breed inside capped brood cells. They suck haemolymph (bee blood) from bees, resulting in the transmission of crippling viruses and deformities including deformed wing. Inflicted bees are essentially paralyzed, unable to feed and perform duties. As the queen’s laying tapers off in the fall, Varroa populations decline, as there are fewer brood cells within which to feed and reproduce. Instead, the mite populations that remain huddle into the wintertime bee cluster, feeding off the haemolymph of adult bees.
The Varroa mite was first documented in the United States in 1987 (in the 1970s apiculturist Roger A. Morse noted these parasites as a likely cause of collapse in colonies in Asia). Tiny reddish brown (about the size of a pinhead) and flat they are visible without magnification.
Here’s some of what Tony shared with me on prevention and treatment of Varroa mite infestations…
Should a beekeeper treat for mites prophylactically or once the problem has manifested itself?
Hives should be treated according to seasonal conditions and mite load. Only if needed based on sampling. This is especially true with the synthetic insecticides since misuse will select for mites with pesticide resistance.
You mentioned you are checking out dead hives now, is this similar timing to past years? Is the primary cause of death mites?
Hive mortality this winter and last fall mirrors that of 2000/2010 due to favorable weather and winter conditions for bees. When the bees are thriving so are the mites.
Should a beekeeper perform the ether or sugar roll on an overwintered hive during a hive inspection in spring, summer, and late summer?
Hives should be inspected for disease, parasites and queen performance: early spring at unwrapping/or around fruit/dandelion bloom (drone brood and/or alcohol wash).
Sample bees from the brood nest, frames of emerging brood and frames of older brood at early pupation. Hives should also be checked mid-summer (July) and September.
Contact Tony for information about hive inspection, bee diseases, pests and their control, advice on good beekeeping practice’s, sound colony management, and licensing(which is required in the State of Maine, and is a good idea).
Recommended reading: Get a handle on Integrated Pest Management “IPM” here. An IPM-based approach involves regular inspections and prevention as opposed to a severe treatment.
Monitor (timeline adapted from Tony’s “A Year in the Apiary-Central Maine”) Pull up a seat and get to know your bees. Observe, observe, observe. According to Tony, monitoring for Varroa is one of the most effective ways to prevent Varroa Collapse, since mite populations can explode under certain circumstances (i.e. mild winters and early bloom, both of which we experienced in Maine last year).
May: Check for symptoms of brood disease and Varroa at the beginning of dandelion bloom. Apply mite treatments and requeen failing queens if necessary. Tony advises bees be managed according to weather conditions and plant cycles (first emergence of flowers…), not necessarily calendar date.
June: Remove mite treatments and antibiotics (according to labels).
July: Monitor Varroa populations. A mite treatment may be necessary prior to supering for the fall honey flow or in lieu of fall honey production.
September: Reduce entrances to hive, apply brood medications and apply mite treatments after the supers are removed from hives.
October: Remove mite treatments in accordance with the label toward the end of the month. (Essential to remove prior to wintering or wrapping the colony in November.)
Evaluating Mite Populations
1-10 mites per 100 bees in a colony is considered low, 11-20 moderate, and 20+ heavy. Eradicating a Varroa mite population is near impossible, so the goal should be to get the number down to a manageable existence.
Ether Roll – Collect 200 + bees from the brood nest (make sure the queen is not in there) in a wide mouthed canning jar . Spray them with ether from an aerosol can (short two-second blast). Replace the lid and rotate. Mites should fall off and stick to the side of the jar. *Note, this kills the bees as does an alcohol wash (pouring of rubbing alcohol into the jar).
Sugar Roll – Same manner as Ether Roll, but instead of alcohol use 1 Tbsp confectioners sugar. This test will not kill the bees. See here for step-by-step instructions. If you attend bee school via University of Maine Extension or The Honey Exchange you should receive instructions on how to do a sugar roll.
Tony does alcohol wash/sugar roles when he participates in field workshops to demonstrate the procedure and difference in sensitivity of the 2 methods.
Screened bottom board is an easy management tool, however it is only effective for a small portion of mites. When combined with a “sticky board” it can also be used to detect Varroa. (In Maine experienced beekeepers argue whether to use a screened board year-round, because of the question of how much ventilation one wants during winter.)
Treatments ALWAYS READ AND FOLLOW THE LABEL FOR ANY PESTICIDE!!! DO NOT USE DIFFERENT PRODUCTS IN HIVES AT THE SAME TIME.
Apistan – there are a number of reports of mite populations developing a resistance to this treatment.
Api Life Var – thymol-based pesticide that kills mites (thymol is a component of thyme oil)
Apiguard – also thymol based, for more information visit the Vermont Department of Agriculture’s site
Mite-Away Quick Strips
Dusting bees with powdered sugar (see January 2013 issue of Bee Culture) *This chemical-free method only removes adult mites that are feeding on adult bees. Most mites, which are inside brood cells, will not be affected by this method.
Grease patties – recipes and instructions in Russ Conrad’s Natural Beekeeping and Ashley English’s Keeping Bees.
**Note, some beekeepers are breeding for hygienic traits. Kirk Webster, a queen breeder in Vermont, has not treated his bees since 1998. Through the years trying to breed bees with Varroa-resistant traits he has lost hundreds of colonies. If his waiting list for bees the past few years is any indication he has found some success. For more information on Webster read Rowan Jacobsen’s Fruitless Fall: The Collapse of The Honey Bee and the Coming Agricultural Crisis.
Images by Sharon Kitchens.Tweet
Sharon Kitchens is a neo-homesteader learning the ins and outs of country living by luck and pluck and a lot of expert advice. She writes about bees for The Huffington Post and stuff she loves on her personal blog, deliciousmusings.com.
When she is not writing, she enjoys edible gardening, reading books on food and/or thinking about food, hanging out by her beehives and patiently tracking down her chickens in the woods behind her old farmhouse.
In her blog, Sharon profiles farm families, reports on farm-based education and internships, conducts Q&A's with master beekeepers, offers tips on picking a CSA, and much more.