Indiana Department of Natural Resources sent this bulletin at 08/18/2021 09:48 AM EDT
Weekly Review for August 18, 2021
This informal report by the Division of Entomology & Plant Pathology is a commentary on insects, diseases, and curiosities division staff encounter on a week-to-week basis. Comments and questions about this report are welcome and can be sent to your respective Inspector.
Ren Hall (Nursery Inspector & Compliance Officer) - RHall@dnr.IN.gov
I found daylily rust at a few different garden centers last week. Also, I am finding plants from the Terrestrial Plant Rule still being sold at nurseries, such as this winter creeper (Euonymusfortunei). If you see a plant from the Terrestrial Plant Rule being sold in Indiana, please contact your nursery inspector to report it.
I’ve received five calls in the last two weeks reporting suspected invasive giant hornet sightings in Indiana. After following up with these callers, it was determined that the insects were in fact cicada killers, which are native and are typically active in July and August. As always, if you suspect you see an invasive insect of concern such as giant hornet, please take some good photos and send them to your local nursery inspector so we can identify it. We’d rather people contact us if they’re unsure so we don’t miss it if the real thing shows up.
This week I am sharing a couple of insect damage related photos.
The first photo shows damage on magnolia from the larva of the magnolia serpentine leafminer moth (Phyllocnistis magnoliella). The larva feeds between the layers of the leaf in this serpentine, winding pattern. When mining damage first appears, leaves can be hand removed.
Also, I have two photos regarding dogwood sawfly (Macremphytus sp.). The first is feeding damage. The second shows two different instars of the dogwood sawfly larvae on adjacent leaves of the same tree. By my finger in the photo, there is a shed exoskeleton. The larvae have different color patterns depending on the instar growth stage. Sawfly caterpillars are the larvae of stingless wasps that feed on plant foliage. They are often mistaken for butterfly or moth caterpillars. (As a side bonus, the little dark ovals/circles with the white frilly border are whitefly pupae.)
I’m starting to wrap up nurseries for the year, but I am still finding some new things from time to time. I inspected a nursery with a fair amount of red headed flea beetle damage. I was expecting to find adults in the weigela, but they weren’t there. Instead, I found heavy populations in the nearby viburnums. This might be due to pesticide applications or a population introduced with newly received plants. Several insects are known to change their host preference as the season progresses and I wonder if RHFB is one of them.
Related to that is one I am just learning about. I noticed the sedum at this same nursery were pretty chewed up and initially dismissed it as more RHFB damage. But sedum is not listed as a RHFB host. I couldn’t find the culprit, but I found this blog post by Joe Boggs at Ohio State about a rather ill-described creature he coins “sedum beetle”. I dropped him a note and he confirmed this looked like the right track. The suspected pest is thought to have two generations, so we might be in between generations. This is one I am going to keep an eye on in the future.
