Insects eating leaf edges in 2016

Asked February 8, 2017, 12:02 PM EST

Hello, I was curious as to what insect(s) were responsible for the huge amount of leaf edge damage last year? It's the first time I've seen even euonymus shrubs and other generally untouched bushes and shrubs totally "scalloped" like roses often are. What is the forecast for 2017? Thank you for any information.

Jefferson County Colorado

1 Response

Hello,
There was no single insect variety that was reported in 2016 as being a major cause of marginal leaf feeding damage. So far, there is no prediction for 2017. You will need to keep a close eye on your landscape this season. If you can catch the culprit, we can identify it and make a specific recommendation for control.

This type of damage on Euonymus shrubs is often caused by the Black Vine Weevil (Otiorhynchus sulcatus). Adult weevils feed on leaves at night, producing characteristic notching wounds along the leaf margin. When abundant, plants may be heavily defoliated. Larval stages feed on plant roots. These injuries may be more destructive than caused by adult feeding. You can use Grubex (available at your favorite garden center) as a soil drench to control the overwintering larval stages. http://extension.colostate.edu/docs/pubs/insect/05551.pdf

Two other insects that can cause marginal leaf damage to a large variety of plants:

  1. Leaf Cutter Bees cut out circles of the leaf edge, which they use to line their nest cells. They are also pollinators, so benefit outweighs their leaf-cutting habits. http://extension.colostate.edu/docs/pubs/insect/05576.pdf
  2. Grasshoppers can be ravenous feeders. If you determine that this is the cause of your damage THIS year, control measures are described in: http://www.ext.colostate.edu/ptlk/1447.html
Best regards,