In Bloom

<< Back to Articles

Ask Burton: Q: We have a Shumard red oak that is having its leaves devoured, and there are huge weird swarms of worms on the trunk of the tree. What is this and how do I stop it?

Posted on April, 19

A: The problem is forest tent caterpillars, a common pest in North Texas in mid-April. They’re social critters, usually concentrating on a branch or two at a time while eating, then resting together on the tree’s trunk. They can strip a lot of foliage off of trees (for us, usually Shumard red oaks), which isn’t good but is rarely a cause for serious concern.  If the tree is in good health, the damage is usually minor.


To keep a healthy tree looking as good as possible, or to prevent more stress to a tree already in fragile health, you can treat tent caterpillars easily. Spraying a low-toxicity spinosad-based product like our Natural Guard Spinosad into the canopy of the tree and simply squashing the insect masses that swarm on the lower trunk can drastically reduce the leaf stripping your tree will take.

Additionally, we’re approaching bagworm season as we get close to May. The Natural Guard Spinosad we recommend for the tent caterpillars works well on these pests too! Spray any junipers, bald cypress, cedars, or other ornamental shrubs you experienced bagworm problems on last year, right now, and head those problems off before they become serious. If your trees have been prone to bagworms in the past, you can use our Bonide Systemic Insect Drench as a preventative now prior to the onset of the infestations. Allow about three weeks for this product to start working.