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Magnolia Tree Tuliptree Scale Infestation

The insect pest, known as the tuliptree scale (Toumeyella Iiriodendri), is impacting the magnolia (Magnolia Grandifloria) tree population in Long Beach. It is an aggressive tree infestation that removes the tree’s sap, causing damage, dieback, and defoliation that can eventually lead to the death of the tree. In addition, the tuliptree scale produces a considerable amount of honeydew, a sticky substance that can coat sidewalks, streets, and parked automobiles.

There are approximately 6,975 Magnolia trees in the city’s 93,500 street tree inventory. These trees have been placed into one of five categories: no infestation, minimal infestation, noticeable infestation, severe infestation and full infestation. The table below provides a summary, based upon the level of severity:

Magnolia Tuliptree Scale Infestation

No Infestation


Minimal Infestation (<25%)


Noticeable Infestation (<50%)


Severe Infestation (<75%)


Full Infestation (>75%)




For street trees with noticeable infestation or higher, removal may be recommended due to the risk of limb failure or tree uprooting as a result of death and deterioration of the tree.

For street trees with minimal infestation, treatment is recommended. The treatment plan includes inspecting, pruning, trimming, and applying a specialized, non-toxic, insecticide to counteract the infestation and prevent the spread to other trees in the city. Two treatments are applied to the tree with two to four weeks in between treatments. The insecticide will not harm bees.

For more information, please see our February 26, 2020 Memo.