Our crepe myrtle trees have moisture falling from them like a light rain.
Dripping From Crepe Myrtle
Certified GKH Gardening Expert
The dripping is the waste or "honeydew" of small insects, called aphids. They can be temporarily eliminated with strong sprays of plain water or plant oil products added to the water. Neem oil is also effective. Unless the stress in the tree that brought them there first place is removed, the pests will return. Stress can be caused by too much or too little water, improper fertilizing, soil compaction, and soil contamination. The following article should be of some help to you: https://www.gardeningknowhow.com/plant-problems/pests/homemade-aphid-control-a-natural-way-to-kill-aphids.htm