Do you have any recommended native host plants for Tiphia vermalis to help control Japanese Beetles?

July 7, 2022 Ask the Expert, Managing Insect, Diseases, and Animal Pests

Question:

I’m thinking of introducing or bolstering a population of Tiphia vermalis to control Japanese Beetles in my yard.  Do you have any recommended (ideally native) host plants for T. vermalis?

Answer:

Katherine Garland, Horticulturist

Thank you for considering the use of biological control options for managing the Japanese beetle (Jb) population in your landscape. While Tiphia vernalis is a known parasitoid of Jb, it’s not one that is commonly introduced in our region and I haven’t seen any research-based information suggesting that introducing them is a practical method for JB control. The following is a statement from Minnesota about the effectiveness of that wasp (or lack thereof):

Two natural enemies of Japanese beetles have been released in Minnesota. The fly Istocheta aldrichi lays eggs on adult Japanese beetles in summer, whereas the wasp Tiphia vernalis parasitizes grubs in the spring. Although both natural enemies became established here, neither is very abundant and they have little impact on Japanese beetle populations. [Source: https://extension.umn.edu/yard-and-garden-insects/japanese-beetles#non-chemical-management-options-1591111].

In our region, the more effective and reliable biological control option is to introduce beneficial nematodes in late August. Milky spore is not a reliable management option in our region. More information on that option and general management tips for white grubs and Japanese beeltes can be found in the following resources:
How to Get Rid of Japanese Beetles (video)
Using Beneficial Nematodes for Grub Control
White Grubs

If you are still interested in purchasing and releasing T. vernalis, you will likely need a permit to do so. Please reach out if you’re interested in learning more about that piece. With that said, here’s a list of food plants known to be utilized by Tiphia vernalis, for those who may already be present in your landscape [Source: https://watauga.ces.ncsu.edu/wp-content/uploads/2020/07/SpringTiphiaWaspGuideSheet-1.pdf?fwd=no]:

  • Peonies, Chinese peony; Paeonia lactiflora; Paeonia spp.
  • Choke Cherry, Prunus virginiana
  • Norway Maple, Acer platanoides
  • Pine trees, Pinus spp.
  • Tulip Poplar, Liriodendron tulipifera
  • Forsythia, Forsythia suspensa
  • American Elm, Ulmus americana
  • Pyracantha, Pyracantha spp