July 20, 2019

Reflections on 2010

A honeybee found with deformed wing virus and Varroa mites.

A honeybee found with deformed wing virus and Varroa mites.

The past year presented several valuable lessons to beekeepers. For example: bees should be managed according to weather conditions and plant phenology, not calendar date; monitoring Varroa is crucial since mite populations can explode under certain circumstances; and the timing and choice of Varroa treatment can have variable outcomes. Also, reading pesticide labels is imperative!


In recent years there has been excessive swarming behavior during the spring and fall, as well as an increase in beekeeping at the hobby and sideline level. The net effect is a higher hive density in certain areas of Maine. The winter of 09/10 was mild by Maine standards and spring arrived about two to three weeks earlier than usual. The mild winter was favorable to feral swarms and weak colonies, and also allowed bees to fl y before forage was available. In early spring strong hives were exposed to reinfestation pressure via their robbing of weak or collapsing colonies. Overall, Varroa buildup was accelerated during 2010 even without spring reinfestation pressure due to early brood production that was in sync with the availability of pollen and nectar resources.

In general, Varroa populations were about three weeks ahead of schedule, just like the plants and bees.

The early spring and associated pollen and nectar fl ows also pushed hive management ahead of schedule. Swarm control, colony divisions and supering all needed attention early this year. A number of beekeepers were caught off-guard due to the unusual weather and scarcity of late April/May queens due to unfavorable weather and a late spring (two to three weeks) in western and southern production areas respectively.

So, swarming was common this spring, but not as exaggerated as in recent years due to three nights of freezing temperatures in May during fruit and dandelion bloom.

In general, most hives were very strong this year at the onset of the late spring/ summer honey fl ows. Bee and mite populations fl ourished during the excellent summer honey flow.

During mid-late July, hive inspections indicated that many colonies were at or approaching Varroa treatment thresholds which are more common in late August/ early September. The hives were strong— boiling with bees and boiling with mites.

Some hives were starting to manifest symptoms of deformed wing virus (DWV) and parasitic mite syndrome (PMS) brood. The early goldenrod species started to bloom by July 4th (two to three weeks early) and beekeepers were in a quandary about the necessity to treat and the fact that hives were still producing honey.

Due to summer drought conditions for most of Maine (except for areas in the north), the honey fl ow shut-off like a spigot toward the end of July or early August, which was both good and bad for the bees.

The good thing was that the dearth offered beekeepers a treatment window for limited materials. The bad part was that in periods of dearth, drone rearing is reduced or stopped; bee populations decline and the mites shift to worker brood and the diminished population of bees. Once the viral complex associated with Varroa is activated, things can go downhill quickly.

Effective Varroa treatment options are limited for northern beekeepers due to widespread resistance to the synthetic miticides (strip formulations) and temperature constraints when using organic materials (formic acid and thymol). At times it may seem as though the treatment is worse than the disease. The key to successful Varroa control is timing, choice of miticide and dosage.

Experienced beekeepers made good decisions since they recalled the summer of 2007, which was similar to 2010 in that there was a good summer flow, a summer drought and no fall flow. The miticide of choice during August was Apiguard (thymol gel) due to warm-hot weather and applied according to label or used at half the dosage (25 gms) and 3 applications instead of 2 applications at full dose (50 gms). Strong hives (minimal PMS, DWV and not collapsing) were treated and weak hives were united prior to treatment. Beekeepers that used Apiguard in summer expressed concern about bee behavior and the effect the thymol had on colonies. Several beekeepers that misinterpreted the label by applying both doses at once (100 gms) called the office to report that the “bees disappeared” after treatment. I could only say, “read the label.”

Both thymol products (ApiLifeVar, Apiguard) and formic acid (MiteAwayII) have language on the label that cautions of adverse effects. These damaging effects are much more pronounced when hives are heavily infested, have active viral infections or low bee populations.

Beekeepers that chose to stick by the calendar and treat hives in September fared well provided their hives weren’t heavily infested. Those who delayed treatment until hives were on the verge of collapse were startled to find that the bees were either gone (absconded), weakened or dead on the bottom board after application of formic acid or thymol. In these instances, the treatment was applied much too late. Remember, one key to successful over-wintering of hives is a hatch of healthy, young winter bees in fall. Another issue beekeepers confronted this fall concerned robbery. The robbery was often initiated by the beekeeper via fall feeding with sugar syrup or when thymol was applied. In other circumstances, the strong hives in apiaries picked on nucs or weak colonies in the yard or within flight range. Again, reinfestation pressure was quite pronounced in treated apiaries this fall due to the dearth, unlike last fall (2009) when there was ample forage. In retrospect, the majority of hives in Maine should have been treated during August and again in mid-September-October.

During the late 1970s and early 1980s, I kept bees on land managed by my friend Jim who was a Vietnam Vet and raised about 1,200 pigs for a living. He was quite a character and had a different perspective, given his experience in Asia. One day, I was helping him out by catching tiny squealing piglets and holding them while he injected them with a syringe of a powerful antibiotic (Tylan). The piglets were sick but looked okay to me. When I asked him about the situation, he replied, “these injections will cure them if it doesn’t kill them.” I’ll remember that ear-splitting day forever, but never thought it would apply to my bees.

I wish you all a very happy and healthy
New Year.

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