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I Got Slimed in Glover Park

Updated: Jun 21, 2023

Have you been walking the neighborhood recently when suddenly your shoes seem to stick to the sidewalk? You try to wipe them off on the grass but they only get stickier? You look around and there is a wide circle of wetness beneath certain trees? If you stand still, it can feel like it is drizzling a little? Every morning your street-parked car seems to get another free clear-coat treatment?

Many think this comes from sap falling from trees in the late spring, though sap does not fall from leaves. No, this is far more revolting – get ready – bug excrement! Yuck. Most likely they are from aphids, or more particularly Linden Aphids which suck up the sap of the littleleaf linden trees, which are numerous in Glover Park. The aphids are yellow/black and the size of a pinhead, so likely you have not spotted them. As they work their way over the linden trees they excrete a sweet, sticky substance that coats everything beneath. This substance euphemistically is called “honeydew” and the ants, bees and wasps love it and the aphids, but they are not numerous enough in the neighborhood to control the aphid population.

If disgusting bug excrement were not enough, and the weather becomes damp, then we can expect “sooty mold” which thrives on honeydew-coated surfaces. Sooty mold is a fungal disease, though not harmful to people, or even the linden trees directly. It can spread enough, though, to block sunlight from being absorbed into the leaves which can stunt the growth or damage the trees.

What can be done to control the problem? DC Urban Forestry - the keeper of the trees - does not consider the aphids to be an invasive species, or a major threat to the trees. It’s just darn annoying and a bit disgusting. Hosing the trees down from above can wash a lot of the aphids off of it, but these trees are big and there are a lot of them. Releasing an army of ladybugs around a linden tree can be effective too, as they will attack the aphids. Importing wasps….probably not a good idea. Honeydew is water-soluble so it should come off cars, shoes, hair and houses easily with a rinse. It’s not likely that the trees are at risk, but a tremendous aphid infestation can drain sap from the linden tree, hurting its growth and causing leaves to turn yellow, and the sooty mold can be a problem too. Aphids potentially can inject harmful parasites into the trees as well.

DC Urban Forestry, a division of the Department of Transportation, cares for and currently tracks 183,443 trees in public spaces and you can view each at their tree viewer map GIS website. DCUF has planted over 6800 trees so far this year. It was a slow news week in Glover Park, so please excuse the article about bug excrement….

Chris Jones

[Editor's Note: On 6/20/23 DC Urban Forestry opened a service request to investigate the aphid invasion in Glover Park and they inspected the trees that day. Here is their response:

"Aphids have been especially prolific this season with dry conditions. Stressed trees are more susceptible to aphid infestations. Trees are still in good health through out these blocks. Healthy trees are seldom permanently negatively affected by pest infestations and I did see lots of beneficial insects feeding during inspection."]


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