This looks like normal, undamaged bark peeling/flaking that is typical for mature Crapemyrtle trees, but it's hard to judge from the photos. Perhaps it was some other environmental factor that impacted bark appearance, but we can say that it was unrelated to the presence of the Spotted Lanternfly. They do not have the ability to damage bark or alter its appearance, as they only have a thin, straw-like mouthpart for sucking up sap from tissues underneath the bark, and the claws on their feet are not tough enough to cut into or scrape off bark. While the hornets that can be attracted to honeydew (the sugary excretion produced by lanternflies and some other insects), and are also capable of chewing bark off of tree and shrub branches, this does not look like the type of damage they cause, nor have we seen them using crapemyrtle before in their collection of wood pulp to make into paper for nest-building.

The bark pictured doesn't look concerning, but you can keep an eye on the tree to see how it leafs-out in spring. If it hadn't been watered at all this past summer (and thus far this autumn), then drought stress is a bigger threat to long-term tree health and vigor. Crapemyrtle are quite tolerant of drought, but we've seen even well-established specimens of a variety of plant species damaged or killed by this year's drought. Our Watering Trees and Shrubs page provides guidance, and it would help to monitor their watering needs until we experience regular freezes.

For the future, a pesticide is not needed or recommended for control of Spotted Lanternfly during the growing season. Systemic products, like the one you describe, are absorbed by plant tissues (roots in this case, it sounds like) and moved into the tissues where pests are feeding, so they ingest the toxin. However, those chemicals also may risk contaminating nectar and pollen in blooms; more scientific study is needed to research this.

That consequence is a primary reason that some types of popularly-used systemic insecticide ingredients were regulated in Maryland (see linked page) so that use by the general public was prohibited; only certified pesticide applicators are legally allowed to purchase and apply products containing those ingredients. (Many landscaping and tree care companies or arborists hold this certification, which is granted by the MDA.) The regulated group of chemicals are called neonicotinoids, and several active ingredients belong to that group. One of those active ingredients, imidacloprid, is used in the product you mentioned, based on label information we referenced on the manufacturer's website. However, you will need to look at the label on the actual bottle that you used, since manufacturers sometimes produce different formulations of a product under the same name, and not all will use neonicotinoids. Given the potential threat to pollinator health, many companies are moving away from using neonicotinoids in systemic insecticides and switching them out for other systemic ingredients.

Spotted Lanternfly has not been found to cause notable damage to Crapemyrtle or other home landscape plants thus far. Crapemyrtle vigor and health is more threatened by pests more specific to that plant, such as Crapemyrtle Bark Scale and Crapemyrtle Aphid, though the latter is more of a nuisance than an actual threat needing intervention to control.

Crapemyrtle shouldn't need regular fertilization, so you can skip that component as well for future actions when managing the tree. Supplying extra nutrients when a pest population is present can also benefit the pest, as some of those nutrients will be in the sap or tissues they are feeding on, essentially giving them a boost in health or reproductive capacity. (Fertilizer might be included in that pesticide product as a means of speeding-up the absorption of the insecticide ingredients, but we're not sure that's necessary either, especially since plenty of products using the same ingredients do not contain fertilizer.)

For now, just water the root zone as needed, and nothing else needs to be done for the Crapemyrtle.

Miri