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Half Moon Disorder,
or Half Moon Syndrome, in Honey Bees

A chap that I correspond with on various Email lists known as "Pav" Asks... Do you really have EFB?

Most of this page is due to his effort, with contributions from others...
I have merely assembled it in the editorial sense, I did allow him editorial oversight after he expressed discomfort with his initial raw email living the life of a web page... Thanks Pav.

Do you really have EFB? (don't burn that hive just yet).

Do you folk have, or have you heard of 'Half Moon Syndrome'?

Briefly, Half-Moon Disorder is a common non-infectious genetic/nutritional (pollen?) problem, the symptoms of which mimic EXACTLY those of EFB.

A few years back a Nelson (New Zealand) beekeeper saw EFB signs in a hive (we don't have EFB in NZ), prompting a full scale Outbreak response from the authorities.

Other hives were found with it, and samples were sent for tests in Australia (where they DO have it).

All the experts involved had no doubt they were seeing EFB - the visual signs were identical.
Some Australian beekeepers started calling for immediate access for their honey to NZ market (currently not allowed, as we try NOT to get EFB). Yet the lab tests came back negative - NOT EFB. The experts were bamboozled, the Australians insisted the lab was wrong, that they recognised EFB when they saw it.

And so we learned about Half Moon Syndrome. Now I've never seen it, except to be shown photos of EFB and told that this is exactly what Half-Moon looks like. And I don't recall (to my chagrin right now) that they have actually figured out exactly what the cause is, although I think nutrition and genetics were predisposing factors [doing some homework since writing the email here, I can confirm that it is a nutrition problem with genetic predisposition - there is no infectious agent involved]. The bit I do recall (my inadequate cerebrum saves space by just holding on to the relevant bit) is that requeening (and supplementary feeding) fixes the problem. Sound familiar?

Since then I often wonder when I hear foreign beekeepers talking about EFB, and how usually its not too bad, requeening will sort it out etc... Are they really dealing with EFB, or do they also get Half Moon Syndrome, and mistake it for the more familiar EFB as our experts did?

Who's heard of it? Where does it exist? Who can differentiate it from EFB without Lab testing?

Subsequently Pav did some homework and later said... " I believe I know the answers to my questions:
-none of you have heard of it
-its everywhere
-HMS is mistaken for EFB very (very) often.
[Positive differential diagnosis from EFB is only via lab tests. More practically though, try requeening and supplementary feeding BEFORE assuming EFB.]"

The New Zealand National Beekeepers Association web-site had some information about Half-Moon Disorder, but it has been removed... It had some online pictures of EFB from the NZ disease recognition booklet. [These have been replaced by the images below Ed.]

EFB infected larvae  


EFB-infected larvae showing yellow/brown discolouration and prominent tracheae.


EFB-infected larva showing 'melted' appearance.

  EFB infected larvae

there used to be this:
"... Half Moon Disorder (HMD) ...
HMD occurs everywhere. How do we know? Because it has been isolated (By Dr. Dennis Anderson - Australia) to a lack of adequate nutrition of the young queen prior to mating. This nutrition is directly related to the number of correct aged nurse bees in the mating nuc/hive. This causes faulty development of the queen's ovaries leading to larvae that are rejected by the feeding nurse bees whereupon they *die of starvation*.

Why was HMD discovered in NZ at such a late date? Because we don't have EFB here. Larvae with EFB *starve* due to competition from bacteria in their gut. In HMD and EFB, the young larvae die at the same age from starvation.

This results in *Identical* visual symptoms. Around the World it is almost certain that HMD is routinely diagnosed as EFB and hence no further explanation is ever sought. Only in New Zealand with its absence of EFB did the HMD mystery attract enough attention to enable it to be explained."

A seemingly less informed article at:- [which no longer exists Ed.
had this to say:
"A number of commenters were concerned about a disorder called half moon syndrome (HMS) that has been reported in New Zealand honeybee colonies. Commenters said there are reports that HMS may have been [[Page 5998]] introduced into Canada from shipments of New Zealand honeybees.

According to our information, HMS is not known to be present in any country other than New Zealand. In 1984, ARS researchers visited New Zealand to study honeybees and honeybee diseases there, and specifically to study HMS. Field tests conducted in New Zealand by ARS researchers to determine the communicability of HMS indicated that the symptoms of the syndrome could not be reproduced in a healthy colony, even when the healthy colony was given a massive inoculum (a comb containing larvae with HMS). In laboratory tests, no pathogen or other causative agent of HMS could be found. Field observations of New Zealand colonies also showed that symptoms of HMS appeared to clear up in time without assistance or treatment."

New Zealand


Pav was writing in response to a mail that Ken Hoare wrote: (to an Email List).

EFB is the big problem both locally and nationally. I believe I noted the figures correctly but in 2000 there were 1060 incidences compared with 850 in the previous year. In my own area EFB has increased two and half times over the previous years figure.

I am not being unkind to anyone, but I guarantee if I had a hundred beekeepers with me at this very moment and showed them a comb infested with EFB there would only be a VERY SMALL proportion that would be able to identify the disease. Let's be honest even the 'experts' find it difficult and send combs away for microscopic examination. Be honest, how good would you be?

But I believe help is already close to hand.

Do you remember the coloured brochures our Ministry distributed, there are several of them, but the ones I have in mind are:

'Foul brood disease of honey bees: recognition and control'
and if you can obtain a copy...
'Statutory procedures for controlling foul brood'.

The following is not my idea and the originator prefers to remain anonymous, but I believe it is so good an aid to disease recognition I have been promoting it a bee talks recently.

The first brochure mentioned has good pictures of bee diseases as far ranging as chalkbrood to American Foul Brood and you cut these pictures from the brochure. You will need two brochures as in removing one picture you then destroy another on the opposite side. Having removed them you paste them onto a piece of thin card and get the whole lot laminated for much less than a pound.

Whenever you are suspicious of the condition of the larvae in the comb it is easy to hold them side by side, not infallible, but a pretty good guide I would suggest.

The second brochure contains a very nice picture of a healthy comb of brood and I suggest you add this to the collection. Have look at it occasionally just to get an idea what you should be seeing. See Bee Estimation [editor]


Blane White of MN Dept of Agriculture

"The latest I have seen or heard on the subject is that it [HMD] is due to a protein deficiency ( or pollen deficiency ) and proper nutrition quickly clears it up completely.

I will pass along an observation from our Canadian friends that half moon seems to disappear from the bees they import from NZ. Just seems to not be an issue in Canada at all."

The following information on Half-moon disorder was picked up from the web, but I regret that I have lost the source, but a different document that contains the same information can be found in this .pdf.

Half-moon disorder (HMD) was described from diseased larvae in New Zealand (Anonymous, 1982). The disease affects larvae of 1-4 days old that die while curled in a half-moon position at the bottom of their cells.

Vandenberg and Shimanuki (1990) isolated and identified Bacillus coagulans strains from HMD affected larvae. The bacterium is a Gram-positive spore-forming rod. Vegetative cells have average dimensions of 0.6 X 3.8 pm. Spores swell the sporangium and are ellipsoidal in shape. Additional characteristics are summarised in Table 2.

Vandenberg and Shimanuki (1990) performed laboratory tests by inoculating larvae with different concentrations of bacterial spores. Results showed that 1 day-old larvae were the most susceptible to infection, especially at doses higher than 2 X 10 cfu per larva, but, in hive tests, inoculation of larvae in their cells failed to produce the disease. They concluded that Bacillus coagulans is probably not the cause of HMD, but, under certain conditions, it can be pathogenic for young larvae.

HMD appears to be a disorder associated with queens. Attempts to spread HMD by transferring combs with dead worker larvae to healthy colonies have failed, but transferring queens from diseased colonies to healthy ones resulted in the onset of HMD (Vandenberg and Shimanuki, 1990).

 Written... Winter 2001, Revised... 09 August 2002, Upgraded... 11 April 2006,
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