Category: mason bee Parasites

Observations on Pollinators , September 2024

In  cleaning out my mason bee nest houses this fall I took the following photos showing some of the variety of pollinators and the parasites I encountered as well .

The first observation was that this was a very poor year for mason bee cocoon production. In many  of the 10 houses like this that I set out on farms in the Metchosin area, there were barely enough cocoons to even break even with the amount of cocoons I had stocked the house with when I set it out in the spring. I believe that spring weather patterns played a big part in the problem 

It may be that early warm spring weather followed by cooler and rainy weather where temperatures did not reach the necessary 13 degrees for several hours a day for hatching and pollination might have influenced the lack of success.

This image of the different types of sealed phragmites tubes shows the presence of different pollinators. note the smooth mud layer sealing versus the fibrous covering .  The smooth ones can indicate the normal blue mason bee or very smooth ones, pollinator wasps ( see below) . The fibrous ones are typical of the smaller species of mason bee, also below.

 

 

 

This is what the normal sized blue mason bee cocoons look like in successful tubes. There can be up to 12 cocoons like this in a phragmites tube.

 

 

 

 

The black cigar-shaped pellets are frass , or bee manure. They often totally cover a cocoon as is shown here in this photo.

 

 

 

 

I noticed his year for the first time that long curly frass like this often was an indicator of the cocoon being parasitized by the mono wasp so I would separate these out and candle them later .

 

This was another parasite finding. the Houdini Fly for which I have provided a separate post for here. 

 

Another different looking cocoon is from a smaller species of mason bee. These are found in the tubes with a fibrous sealant as mentioned above.
The cocoons of the smaller version of mason bees appear with a silvery coating over them . Identification of some of the mason bee species is difficult. I have included many on my iNaturalist site  at https://www.inaturalist.org/observations?subview=table&taxon_id=630955&user_id=garryfletcher

 

 

 

I also found several tubes where several species of mason bee had shared the same tube, although this is not very common.  Here you can see the three larger blue mason bee cocoons near the bottom

 

 

 

Below are some of the different small sized mason bees that hatched this year

So my last message is that you need to be prepared for several alternatives when you open your Phragmites tubes in September and don’t throw away those other good pollinator species.

See also this post on Some more new pollinators from last year

Also see this post on other pollinator species and on the mason bee mites

This link is to an iNaturalist curator , Dr. John Ascher who is an expert on pollinator bees

Houdini fly invasion


Two years ago I had never heard of the Houdini Fly.  However at that time  they were starting to  turn up in the Duncan area. This year I encountered them in several of my mason bee nest boxes I have placed on surrounding farms in the Metchosin area so they are a recent invading parasite for mason bee larvae production.

These are probably the most destructive parasites of mason bee colonies as they will eat through all the cocoons in a tube if allowed to remain through the fall and winter. The best solution is to clean out the mason bee incubating tubes as soon as possible, even as early as late August. It is important to leave those tubes that have not been sealed by then for a few more weeks in the bee house as later nesting leaf-cutter bees and other pollinating wasps and bees may still be working.

Not cleaning out your colonies early may lead to total cocoon production  failure.

See this link for other parasites of mason bees:
https://gfletcher.ca/category/mason-bees-and-phragmites_reed-grass-tubes/mason-bee-parasites/

Electron Microscope Images of Honey bee Mites

legs from bottom , ventral view

At the Seedy Saturday on the weekend where I was selling mason bees, I met Dr. Elaine C. Humphrey, Fellow of Microscopy Society of America, and a  Past President Microscopical Society of Canada. She works at the Advanced Microscopy Facility.
Bob Wright Science Centre A015, University of Victoria.

Dr. Humphrey has provided the following images she has taken using Scanning Electron Micrography of the Varroa mites that are parasitic in honey bees:  ( Varroa mites (Varroa destructor and V. jacobsoni) )colonies.

These mites are similar in name only to the mites that infect Mason bee tubes, Chaetodactylus krombeini, (Krombein’s hairy-footed pollen mite).

According to Wikipedia:  ” The common name is somewhat misleading, as pollen mites consume more nectar than pollen. Both their feeding habits and their size differ significantly from Varroa destructor, the mite very harmful to the European Honey Bee. Although both are classified as mites, varroa mites are more closely related to ticks and only distantly related to Chaetodactylus. ”

So you can expect to have hairy-footed pollen mite contamination if you are not conscientious about cleaning out your tubes in the fall.  See this reference on mason bee mites:

Beware the Houdini Fly!

Last year (2023), I first heard about the Houdini fly and I posted a message here about them occurring in the Duncan Area. Recently while i have been cleaning out my tubes I have found them in two of the locations where I provide bee boxes for my neighbours . One was in the Tower Point area  where most of the tubes in one bee house were affected. The other was in the William Head area of Metchosin.

So it is essential that any old boxes with tubes should be eliminated or cleaned regularly if they are going to be reused. The Houdini flay maggots will consume all the cocoons in a tube . They are much larger than the Mono wasp larvae which are always inside a cocoon case.  Also note the twisted purple mass of what I assume are feces

From Wikkipedia:

Cacoxenus indagator is a species of fruit fly.[1] It is a kleptoparasite, laying its eggs in the pollen-filled nest cells of mason bees.[2] On account of its ability to break out of those cells once hatched, it is commonly known as the Houdini fly.[3][4]

Scientific classification
Kingdom:
Animalia
Phylum:
Arthropoda
Class:
Insecta
Order:
Diptera
Family:
Drosophilidae
Genus:
Cacoxenus
Species:
C. indagator
Binomial name
Cacoxenus indagator

Loew, 1858[1]

Beware : THE HOUDINI FLY-(Cacoxenus indagator) Kleptoparasite of Mason Bees

Recently there is a concern in the Pacific Northwest about an invasive species, the Houdini Fly  (Cacoxenus indagator) .  which is a kleptoparasite which invades mason bee homes and destroys the developing larvae and source of food pollen.
Brian Guzda of Brian’s Mason Bees  (https://www.instagram.com/briansmasonbees/?hl=en ) provided this picture. Note that the white maggots are not contained within the cocoon as they are with the Mono wasp, another kleptoparasite which I profile in other posts here.  It is essential to clean out whatever kind of tubes your mason bees have capped any time from October to December in order to catch these flies before they mature and cause further damage. hou

The following video gives more information about this invasive species and emphasizes the importance of taking good care of  your bees.

 

https://agr.wa.gov/departments/insects-pests-and-weeds/insects/apiary-pollinators/pollinator-health/houdini-fly

New species of mason bee showing up in some Phragmites tubes from last year

One house had a better-than-average set of mason bee tubes filled, but many ended up with very few cocoons.

The past season was not a good one for mason bees on southern Vancouver island. Cool temperatures delayed hatching and there was poor fertilization in some of the locations . I had mason bee houses stocked with Phragmites tubes and mason bee cocoons in eight different farms of neighbours.

As I have been cleaning out the tubes and getting the cocoons in the refrigerator for storage, I have noticed a significant increase in a species of native mason bee that is much smaller than the native blue orchard bees.

 

 

Another interesting observation. was that at the bottom of the tube below the cocoons in several tubes there was a pocket of the dead but hatched parasitic mono wasps..  I cant explain that one (my best hopes would be that this smaller mason bee cocoon has some super power over the parasitic wasps…lol)

Mites infest Costco Mason Bee houses

 

 

 

So once the house had all the tubes and trays removed,. The cleaned trays were reinserted and the bamboo tubes were replaced with very short Phragmites reed grass tubes. Now its ready to be placed outside

 

Cleaning the tubes, Nov.-Dec. 2021

CLEANING THE PHRAGMITES TUBES.

Any time from September on it is safe to open the Phragmites tubes to collect the mason bee cocoons inside. The earlier you do this the better as it prevents further development of pollen mites.  Below are some photos from this years crop.

The ideal tube that you want to find will look like this

Occasionally I come across large white larvae in the tubes. These are not parasites, they are pollinator wasp species. See this post for photos of the wasps

Beneficial wasp pollinators.. do not destroy!
When one of these tubes shows up I simply carefully replace the other half of the phragmites tube and tape it together. I incubate these in a separate container in the refrigerator
So this is what a successful bunch of tubes looks like. These tubes are about 18 cm in length.

PARASITES of MASON BEES

Pollen Mites 

With a hand lens or as above, a closeup view on a cellphone you can see this mass of mites on the move. When I come across a tube with these mites, I segregate all other cocoons from the tube, and give them a thorough wash and cleaning before storing them in the refrigerator. I am also careful not to sell any of the cocoons from that batch. Mason bee houses that are not cleaned will have a build up of mite infestation so bad that eventually very few bees will be produced.

MONO WASPS:

I didn’t have many of these Chalcid wasps ( Monodontomerus) this year, I have done a previous post showing these in detail. These are “bodysnatchers” as they lay eggs on developing larvae which then eat the larvae

However, some other bodysnatcher parasite did get in and eat cocoons in a few tubes, typically leaving half the cocoon casings.  I am not sure what this one is , but usually all the cocoons in a tube will have been opened if these have entered.

Mummification: 

A hard dark colored mummified larvae on the right is produced inside a cocoon. Probably spores of the fungus would be released from this form.

This is similar to a fungal infection called chalkbrood  in honeybees.

 

 

 

UNKNOWN?

A new parasite turned up this year in a few of the plastic cases with channels which a neighbour gave to me.  This one is like a cutworm larvae. I find the plastic containers are very bad for parasites, especially mites.

Other entries on this website about parasites and Problems with Mason Bee Culturing can be found here

Crownbees.com also has an excellent article on parasites of mason bees.

 

Mason bee larvae and predation

I know I should have put the chicken wire fencing up sooner, as a bird, probably a woodpecker or a rat  pulled out the top 4 cm of tubes from two of my boxes, Fortunately it never opened all the tubes but a few were broken so I was able to open them and see the larvae stage inside

 

you can see the larvae attached to the plug of pollen in each section of the phragmites tube. At this stage one should not move or jar the tubes as the larvae can fall off the plug of food.  I was able to tape back up the tubes and the larvae inside should survive OK as long as they can reattach to the food pellet.

The solution, 1 inch opening chicken wire:

Mason Bee Morgue

So that’s what we call them when people drill holes into blocks of wood and then never clean them out. The result is an eventual loss of the colony from an ever increasing infestation of mites.

If you aren’t willing to look after and properly clean your colony every year in the fall, then you are not doing a service to help in pollination, you are harming it.