By Chris DiFonzo
Earworm flight
Ander Huseth, MSU Extension specialist in the Department of Entomology, reports that earworm catches in his pheromone traps tripled in the last six days, and that perhaps we are at the beginning of a flight from the south. This is good time to scout crops like late-planted sweet corn that are susceptible to earworm infestation. To learn more about scouting and treatment, read the MSU Extension article “Identifying late-season caterpillars feeding in corn ears.”
Discovery of Dectes stem borer damage
The following details the discovery of the first (to my knowledge) Dectes stem borer infestation documented in Michigan. I don’t know a lot about this insect, but I’ve summarized the following and provided pictures. Keep an eye out for this pest and damage over the next six weeks as you conduct field calls or troubleshoot poor stands. If you find it, email me at difonzo@msu.edu with a few pictures and a location so that we can understand its distribution. Dectes is likely another example of a southern pest shifting northward as the climate steadily warms.
Last week, I received a text with pictures of a mystery caterpillar-looking larva found in a soybean field west of St. Johns, Michigan. I recognized the larva as Dectes stem borer (Dectes texanus texanus) — not a caterpillar, but a longhorn beetle. For years I’ve listened to entomologists from the south discuss this pest, which is found on the High Plains in Kansas, Oklahoma and Texas as well as the southern U.S. up into Missouri and Kentucky.
In 30 years at MSU, I’ve encountered only a few adult beetles while sweeping beans and I’ve never seen larvae or damage. The insect collection at MSU has only two beetle specimens, both dating to the 1970s, and no larvae. My field crops colleagues at Ohio State and Purdue also have never seen an infestation. It is no surprise, however, that Dectes is spreading northward since the 1970s, with millions of soybean acres, more no-till production and warmer winters.
Source : msu.edu