Magnolia Scale

What is Magnolia Scale?

Magnolia Scale is a common insect/pest that’s fairly common in Wisconsin. Their females lay eggs on trees which then hatch and feed on the tree’s circulatory system causing damage by sucking out the tree’s sap and depriving it of the nutrients it needs to survive. They can cause a great deal of damage to their ‘hosts,’ including stunting growth, killing off branches or in the worst cases – killing the entire tree.

What does Magnolia Scale look like?

Magnolia leaves turn black from a sooty mold that grows on the clear sticky liquid that the insects secrete. Wasps, bees, and ants are attracted to the plant to feed on the secretions.

Scale insects are most noticeable in late spring and summer when they appear as whitish lumps up to 1/2-inch long along the branches. In severe infestations, entire branches may be coated with scale and have a chalky appearance.

These insects appear in early spring as tiny dark specks. The specks are immature scale insects called crawlers (the only life stage at which the insects move). As it feeds, each crawler grows into a waxy, whitish lump. The mature insect lays eggs over the summer, which hatches into a new generation of crawlers in late August to September. The crawlers overwinter and begin to move again when temperatures warm in the spring.

How do I treat Magnolia Scale? 

Dealing with Magnolia Scale on your own can be problematic – especially when using traditional insecticides. Not only does their waxy coating protect Scale from directly sprayed poisons, it can also kill a lot of the insect’s natural enemies and keeps them from feeding on the very same bugs you’re trying to kill. It’s best to call a certified arborist from Capital City Tree Experts. If left inadequately treated, the problem will only worsen year to year as the Scale will mate in the fall and leave behind their offspring to spread even heavier the following year.