Good News! Beneficial Insects Found on Magnolia.

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So I started getting some queries about a new mealybug found on Magnolias in the landscape.  You can imagine my despair, the poor magnolias have their fair share of sucking insect pest problems with the glut of Magnolia scale we are finding on our beloved specimens.

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Steve Paiero, University of Guelph

So we took a closer look at these mealybugs and looked at some fresh samples.  The waxy decolletage certainly reminded me of a mealybug but there seemed to be an impostor underneath the waxy filaments.  What we found were…. empty shells of an insect body. But what?

The adult Hyperaspis ladybug searches for prey near a mound of scale insects.

We also received some photos of these guys of what the arborist thought were incidental beetles.  And it was these guys which really helped us put all the pieces together.  These are predacious ladybird beetles from the genus Hyperaspis.   They eat other insects.

Aha, the white guys aren’t plant sucking mealybugs, they are larvae of the predatory Hyperaspis ladybird beetles.  Mike Raupp, University of Maryland explains it all in a great article.  Basically, the waxy filaments “disguise” the Hyperaspis ladybird beetle larvae and confuse other predators and parastites that might want to use them as a food source.  Both the Hyperaspis larvae and adults consume vast quantities of Magnolia scale nymphs (probably hundreds to thousands each) and can really crack down on the scale population.

So don’t kill them 🙂

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(Lower right) Emerging Hyperaspis beetle adult from pupal cases (R. Kraus, bugguide.net)

 

 

About Jen Llewellyn

OMAFRA Nursery and Landscape Specialist @onnurserycrops
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