How Hemlock Wooly Adelgids Spread is Finally Discovered!

The hemlock wooly adelgid is one destructive little pest. They kill hundreds of thousands of trees in the U.S. every year, and are a major issue that experts having been trying to control for years now. The biggest question circulating is how these little critters are able to get around, spreading vast distances to destroy forests that are thousands of miles apart. They can’t fly, so how are they able to spread as fast as they do? Answering this question could help experts make huge strides in being able to control this destructive pest.

Scientists recently did a thorough study of how they could be hitching rides on birds in order to spread these vast distances, and a recent report outlined exactly how they most likely do this. Researchers found that the birds migrating and taking a short rest on the hemlock branches were the prime targets for the wooly adelgid. There are two ways the insect hitch a ride on the birds. The adelgid nymphs known as “crawlers” will disperse after emerging from their egg sack and find a free space on the tree to feed. When a bird lands on the tree and happens to brush up against places where crawlers are feeding, those crawlers happen to get picked up by the birds. The birds that brush up against branches pick up the most crawlers, however, the little crawlers don’t just leave everything to chance. Many birds that simply perch on a branch will also pick up a good number of crawlers, meaning the adelgida aren’t simply passive hitchhikers. Researchers also found that birds picked the most adelgids during the month of May. The researchers plan on continuing these studies in the hopes that having a better understanding of when and how the birds disperse the adelgids will then lead to better way of controlling the spread of these destructive pests.

In light of this study, how do you think researchers could use this information to control the spread of the hemlock wooly adelgid?