Where do thrips come from?

Thrips are a common insect pest that most growers have had difficulty controlling due to their small size and ability to hide in plant parts. Although this is not an insect associated with growing media, most species of thrips spend part of their life cycle in the growing medium or soil. Thus, the question arises whether they can come from unused, packaged growing media. The simple answer is that it is very unlikely. To understand why, this article from PRO-MIX addresses the life cycle of thrips and the common issues associated with them.