- A study examined insects caught in straw mats used to wrap pine trees over four years and found that 55% were beneficial insects while only 4% were harmful.
- The mats contained hundreds of spiders and assassin bugs that prey on harmful insects. However, egger moth caterpillars and nematodes that damage trees remain on the trees after the mats are removed.
- The traditional practice of wrapping trees in winter is thought to provide places for beneficial insects to survive the winter. However, the study found that burning the mats after removal kills both harmful and beneficial insects, so a better approach is needed.