Pests (Insects & Snails) Popping Up Here And There In Soybeans And Pastures

DR. RAUL T. VILLANUEVA

LEXINGTON, KENTUCKY

The past week and into this week, I have received inquiries about different insects appearing in several Kentucky counties.

 In Graves County, there was a report of a snail species consuming soybean foliage. This snail seems to be a different species than the one in my previous KPN report. In addition, I observed the presence of snails in various fields in Caldwell and Trigg counties despite warmer temperatures occurring in August.

 In Clinton County, Colby Guffey (County Extension Agent for Agriculture), reported extensive defoliation of commercial soybeans due to the Mexican bean beetle (Epilachna varivestis). This beetle is in the same family as lady beetles (Coccinelidae) but specializes in defoliating legumes. Based on the images I received and comments from Mr. Guffey, the threshold for this insect in this field had already passed. The economic threshold, using the shake cloth method during pod set, is 16 or more larvae or adults per a 4-row feet.

In Ballard County, Tom Miller (County Extension Agent for Agriculture) reported the presence ofarmywormin pastures; he observed “3 or 4 small worms per sq ft.  Most ¼ inch or smaller.” These larvae may be the fall armyworm (Spodoptera frugiperda,Noctuidae) due to the time of the year, or it may be theyellowstriped armyworm(S. ornithogalli) (Figure 1). The latter insect rarely causes damage in soybeans or corn, but this year, it has been observed in large numbers in soybeans, corn, and alfalfa since early June to the present. Early this year, I observed an abundance of yellowstriped armyworms, along with abundant oviposition, in multiple Kentucky counties.

County Extension agents, farmers, private consultants, and scouts need to be on the lookout for unexpected pests. This year is providing an unusual abundance of sporadic pests such as the Mexican bean beetle and yellowstriped armyworm.  ∆

DR. RAUL T. VILLANUEVA: University of Kentucky