Hold On to Your Crape Myrtles

Lagerstroemia, more commonly known as crape myrtles, are a popular flowering tree found across the United States due to their low maintenance and durability. Native to southeast Asia and India, crape myrtles are incredibly durable trees that are well known for both their incredible durability and low maintenance. Interestingly enough, crape myrtles are a staple in India, where in addition to the wood of some species of crape myrtle being used as construction timber, they are also a food plant to the Lepidoptera species which produce tussar silk. Tussar silk is produced by several different species of silkworm and is fairly valuable due to the way that it has to be harvested and treated in order to weave it into a usable fabric. India is the second largest producer of tussar silk so this is a major export for the country and a central part of the culture since a lot of clothing, among other things, is made with tussar silk. Hence, crape myrtles being as resilient as they are is a very helpful trait for a tree that the species of moth & butterfly that tussar silk comes from have to feast on.

There are around 50 species of crape myrtle, but they all more or less share the same attributes. For example, crape myrtles are best known for their clustering flowers that start to bloom in the late spring/ early summer in an array of colors ranging from whites to different shades of pinks and reds. In addition, the trunk and branches of the tree have a mottled appearance that arises from the bark shedding throughout the year.

When we say it takes a lot to actually kill a crape myrtle, we mean that you can cut the tree down, dig up the stump, and there's still a chance that the tree will come back. Crape myrtles have been near impossible to kill even by the most inept of gardeners, until now. There's a parasite targeting crape myrtles for their sap, a species of aphid causing crape myrtle bark scale. It's a small white bug that functions similar to "regular" aphids found on non-woody plants. The difference here is that this species seems to be just targeting the crape myrtle tree. Crape myrtle bark scale is caused via a chain reaction caused by the aphids feasting on the sap of the tree. The aphids consume the sap and then produce honeydew. Honeydew is sticky and relatively fragrant so it attracts other bugs (such as flies) that end up stuck to it along with debris in the air. Eventually, the honeydew covering the tree gets completely covered, creating the perfect environment for a fungal infection, specifically sooty mold. The mold, easily recognizable by its dark black color, is difficult to kill and can very quickly become a problem for the crape myrtle tree, as wherever it spreads the tree is no longer able to photosynthesize.

Who knew - the weakness to the virtually indestructible tree was taking away its ability to breathe and process food. Aphids are a menace to gardens in general, as what they do to crape myrtle trees is the same thing they do to "regular" plants. Only, for the crape myrtles, there are no sprays that are effective in stopping the aphids nor is there an effective treatment for killing the sooty mold, so currently, nurseries are curbing or dropping sales of crape myrtles completely. So far, the highest impact has been in Washington D.C. and some cities in Texas, but it would not be a surprise if the aphid infestation spread rapidly throughout the rest of the United States. While an infestation like this would merely affect the aesthetic of some places in the United States, depending on how popular the tree is in the area, the sudden death of a large portion of crape myrtles could be detrimental in other places. For example, consider what this plague could do to the tussar silk production in India. That aside, the environmental impacts would be large as well since the critters that depend on the crape myrtle for food would either have to adjust to consume something else or starve.

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