A common predator of leafcutter bees is a parasite called Pteromalus venustus, a very small wasp that parasitizes alfalfa leafcutting bees (ALB) (Megachile rotundata). They are sometimes referred to as parasites, Pteromalus, chalcid wasps, chalcidoids, or parasitoids, and can infest your Bee House. While you cannot always stop these issues from showing up, there are a couple of actions you can take to prevent the spread!
Below, we will discuss common issues that affect leafcutter bees, how to identify them, and a couple of methods you can use to keep your friendly bees safe.
Chalkbrood & Pteromalus Venustus
Pteromalus venestus and chalkbrood are the most likely culprits to find in your Bee House. These invasive species infect the cocoons in leafcutter nesting tubes, spreading to each nest and killing the growing larvae. Here’s how you can identify them:
How to Spot Chalkbrood
You can spot this disease by locating hard, shrunken cocoons in the nesting tubes. While chalkbrood is not found in Saskatchewan, where our bees are raised, there is a risk that your nesting tubes may develop this disease if not replaced yearly with new, clean nesting tubes. If you spot chalkbrood in your Bee House, you will have to throw out your current set of nesting tubes, as we do not recommend that you remove this disease. Fortunately, you can always order a new set of tubes and replacement bees from our Shop!
How to Spot and Stop Pteromalus Venustus
Pteromalus venustus are small black bugs that infect the eggs inside leafcutter bee cocoons, eating the bee larvae and damaging the cocoon surface. If you catch these parasites early, you can prevent them from spreading to your presently unaffected bee cocoons. You can take the following measures:
Spreading Cinnamon: Add a pinch of cinnamon to your box containing the bee cocoons. The strong scent of this spice will deter pesky parasites from making themselves at home. Shake the box carefully to sprinkle the cinnamon without disturbing the bees. You can also spread cinnamon around the nesting tubes.
Spreading Powdered Clove: Powdered clove is perfect for deterring parasites. Like the cinnamon, you can spread clove powder around the nesting tubes or inside your bee cocoon box.
NOTE: You should only follow the above practices if you spot parasites in your nesting tubes, and not as a preventative measure. Only spread a small amount of cinnamon and clove, as these strong spices can also deter the bees from nesting in the Bee House if you use a significant amount.
Final Thoughts
While you cannot always prevent invasive species from infesting your leafcutter nests, you can prevent the spread of Pteromalus venustus by catching them early. Regular inspection of your Bee House will allow you to spot this parasite before it spreads to your other bee cocoons, leaving you with healthy, happy, and friendly bees!
At Kind Bee Farms, we sell full Pollinator Kits for leafcutter bees, including nesting tubes, a Bee House, and a box of busy bees ready to buzz off to work. Our Bee Homes are designed for easy bee care, and with the tips in this guide, you can keep your little friends happy and healthy through the growing season! Visit our shop to learn more about our Pollinator Kits.