Using the oxalic acid dribble method for varroa mite control.
[/vc_column_text][/vc_column][/vc_row][vc_row][vc_column width="1/3"][vc_column_text]Oxalic acid is an exciting new tool in varroa mite management. The two most common application methods of oxalic acid are sublimation (vaporization), and the dribble method. Of the two of these, we prefer the oxalic acid dribble method in many situations.
Many people are rushing to buy oxalic acid sublimation tools (vaporizers) to take advantage of the ease of use and the minimal intrusion. These tools are great for times when the temperatures are cold, and opening the hive can be detrimental to colony health.[/vc_column_text][/vc_column][vc_column width="2/3"][vc_video link="https://www.youtube.com/playlist?list=PLzEyk_vwcWWXPnwPKj5V2dDusBpBFPFcx" css_animation="fadeIn"][/vc_column][/vc_row][vc_row][vc_column][vc_column_text]There exists, however, a much quicker and less expensive method of application. We believe the intimidation factor is one of the main things preventing widespread adoption of the dribble method. We hope that the three videos in the playlist above show how easy this method of mite control truly is.
Please keep in mind that no matter which method you choose oxalic acid has some limitations. First, oxalic acid does not kill mites that are reproducing in capped brood. This means that it is most effective when there is no capped brood in the colony. Second, oxalic acid in not approved for use with honey supers on.[/vc_column_text][/vc_column][/vc_row]
We’ve got some changes to our recommended varroa mite management strategy. Both of these changes have to do with more recent evidence of mite migration from collapsing or infested colonies.
We have previously recommended that August be our final mite check for the year and that once you had the supers off, mites knocked down and hives full of honey, you were done.
We now recommend monthly monitoring until the weather is too cold to disrupt the hive. Into September at least. This is because we’ve heard of the following happening. A mite count was performed in August with the treatment threshold being reached, (7 mites in 300 bees) and the hive was treated with Apiguard. Two weeks post-treatment, another mite count was performed with there only being one mite in the sample. Success right? One month later, in mid-October, another count was done with the results being somewhere in the 40s.
The mites came from other collapsing or heavily infested colonies nearby.
Second, we have told people only to treat colonies where the threshold is exceeded. Again, because of mite migration, we are now recommending that if any one of the colonies in an apiary exceeds the treatment threshold, that all colonies be treated.
Also please remember that good Integrated Pest Management practices call for other means of control before chemical control. The most successful of these being drone brood trapping/sacrifice.
August is a month where a lot is happening for beekeepers in this area. Often times, during the summer months things are on coast. Checking to see if additional supers are needed and monitoring mite levels and general hive inspections become a comfortable routine. This changes in August.
Hot and dry weather causes flowers to stop producing nectar. A lot of the nectar abundant spring and early summer flowers such as sweet yellow clover are done blooming, or will be shortly. This period of minimal nectar flow is also known to beekeepers as a dearth. Some people who have stopped feeding first year colonies may need to start feeding again to get comb drawn. There’s still plenty of time to get stores, naturally through nectar collection or artificially through feeding, into comb, but getting comb drawn becomes tougher and tougher as the summer progresses. We recommend feeding first year colonies at least until all the comb is drawn in the brood chamber and overwintering area. Traditionally, in this area, this means two deep boxes of comb.
The dearth can cause also hives to become more defensive. New beekeepers who have been dealing with calm, gentle bees are often taken by surprise the first time their bees seem a little more grumpy. Additionally, colony numbers are up so, there are more guard bees increasing the likeliness of stings. We recommend always having your smoker lit, even if you don’t plan on using it. It’s a lot easier to put it out with extra fuel still in it, than to light it with a defensive colony open and needing smoke. Additionally, we recommend always wearing at least a veil. Getting stung in the face isn’t very fun.
This is also the critical time period to make sure that your varroa mite levels are under control. As the brood area has expanded through the year, so have the number of places for varroa to breed. As the brood area contracts in the fall, the mites become concentrated in fewer and fewer brood cells quickly overrunning a colony with viruses. Also because you want the bees that raise your winter bees to be healthy, now is the time to do final mite counts and treatments. The CSU extension office says in it’s IHM (integrated hive management) publication that “Harvest time is a critical time to check and treat for Varroa mites. (It is critical to monitor and treat, if necessary, before the end of August in Colorado. The most damage from Varroa usually occurs in late summer and is the primary reason colonies don’t overwinter successfully).”
Mite treatment often means supers need to be harvested. Many of the varroa treatments are not approved for use when honey is being collected for human consumption. With the dearth upon us, or quickly approaching, the benefits of leaving honey supers on versus removing them in a timely enough fashion to treat for varroa mites are easily weighed for most of us. Additionally, leaving what fall flow there may be for the bees is probably a more healthy choice for the bees as nectar is nutritionally diverse in a way that sugar syrup is not.
Now is also the time to make sure that you are happy with the queens that you have going into winter. Queen availability is coming to an end. Decisions should be made soon about combing or requeening colonies.
Good off season preparation starts this month with harvesting, mite treatments, and checking stores.
Winter is coming