Woolly Adelgid is an invasive insect species that attacks and damages hemlock trees. They are also known as Hemlock Woolly Adelgid or Hemlock Adelgid. There are several synonyms for this insect species, including Woolly Aphid, Woolly Bug, and Woolly Scale. While these terms may be used interchangeably, they refer to different insect species with similar physical characteristics. Woolly Aphids, for example, are smaller in size and feed on a variety of plants, while Woolly Scales are typically found on citrus trees. Despite their small size, Woolly Adelgids pose a significant threat to the health and longevity of hemlock trees and their ecosystems.