Pink caterpillars make oaks less than pretty, but probably won’t kill them

This is a field note from PhD student Kristi Backe.

Pink-striped oakworms are chomping on oak trees in Raleigh right now and leaving piles of frass (poop) in their wake.  They’re not too choosy about oak species, and this week I found them on sawtooth oak, white oak, and pin oak. Spot them on your trees by looking for branches with all of their leaves chewed off.

Pink-striped oakworm, Photo: KM Backe

You might be more familiar with the orange-striped oakworm, a closely related species that will be out in full force in a month or so. We already have a few posts about orange-striped oakworms up on the blog (HERE, HERE, and HERE), and the management tips in those posts will work for pink-striped oakworms too. Bottom line: oakworms don’t usually do serious damage, and the easiest way to get rid of them (if you bother to get rid of them at all) is to prune off the branch that they’re feeding on. They feed in large groups, so you can wipe out a lot of them with one cut.

Pink-striped oakworms feed in groups. Photo: Kristi Backe

Typical defoliation on an oak branch. Photo: Kristi Backe

You can also count on predators and parasitoids to help keep the oakworms under control. This week I noticed a Tachinid fly laying eggs on a bunch of caterpillars.

Can you spot the Tachinid fly? Photo: Kristi Backe

She would lay an egg and then move on to the next caterpillar in the line. The fly larvae that hatch from those eggs will eat the caterpillars from the inside out – a little gory, but it will help keep the oakworm populations down!

Tachinid fly laying eggs. Photo: Kristi Backe

2018-01-17T11:30:49-05:00 July 13th, 2017|Categories: Natural Enemies, Natural History and Scientific Adventures, Urban Ecology|Tags: , |

About the Author:

Kristi Backe
I am interested in urban ecology and am studying relationships between street tree diversity and the makeup of arthropod communities in trees.