Pillbug
Earlier in the season, pillbug (known as Roly Polys) damage in soybean fields was noticed in eastern NE. They are common in no-till irrigated fields. Pillbugs like moisture and cover, and do not like to be exposed to direct heat and sunlight. Once soybeans emerge, these bugs clip the cotyledons off at the hypocotyl (the part of the stem just below the cotyledonary node) which eventually kills the plant. As the temperature rises and conditions become drier, pillbugs will be less active in the field. If damage happens often, replanting sections of the field should be considered. Managing pillbugs is challenging. Results from foliar applications have been mixed, and cultural practices such as strip tillage, burning crop residue may be beneficial, but may not align with our current agricultural methods.
Japanese beetle
A pest that generally isn’t an issue in southeast Nebraska is the Japanese Beetle. We are seeing more and more of these beetles in the area each year, but to date they 
have not caused economic damage to corn or soybeans. Japanese beetles can contribute to defoliation in soybeans, where they skeletonize the leaves, leaving only the leaf veins. If they defoliate 30% in the vegetative stage or 20% in the reproductive stage, soybeans should be treated with an insecticide. Here is a link to a chart from NebGuide G2259 that explains how to estimate insect defoliation in soybeans: https://i0.wp.com/cropwatch.unl.edu/2017-CW-News/2017-images/insect-management/soybean-defoliation-guide.png?ssl=1. In corn, the adult feed on leaves, tassels, silk, and pollen. The leaf feeding is not economically important, but the main concern is silk clipping which may cause reduced pollination. There are several types of insecticide that are effective in controlling this pest, but you may need to spray multiple times. Insecticides available to control Japanese beetles are listed in 2024 Weed Guide.
Soybean Gall Midge
Soybean gall midge (SGM) has been a major problem in eastern NE for some time. Entomologist Dr. Justin McMechan and his team are evaluating the impact of soybean gall midge at ten sites across eastern NE. They have already reported adult emergence in Saunders, Lancaster, and Otoe Counties. The adult gall midge overwinters in the previous year’s soybean field and subsequently flies to the adjacent field to lay eggs on young soybean plants. That is why it is crucial to scout field borders for early detection of soybean gall midge especially where a history of issues with gall midge injury has occurred. Once the egg hatches, young larvae start feeding on soybean plants. This results in dark brown or black discoloration at the base of the plant below the cotyledonary nodes and plant becomes prone to breaking off at the base. As the larval population increases, discoloration spreads around the stem. Peeling back the outer layer of the stem reveals orange or white larvae. Larvae can be observed as early as the V2 stage (2nd leaf stage) of soybeans. Managing soybean gall midge has been difficult. Foliar sprays have shown some response but are inconsistent between locations and years. No specific foliar-applied product tested to date has provided consistent control. Research suggests that growers can consider using a combination product that contains a pyrethroid.
Soybean Stem Borer
Another pest that has been around for a few years is the soybean stem borer. If you do identify stem borer in your soybeans, try to harvest these early as possible, due to lodging of the infected soybean plants. If you have a field that has soybean stem borer or know of a field that has this pest near your field, you may want to consider not planting soybeans in that field for a while. Longer season soybean varieties which mature later also are suggested because they have a longer time to harvest before they lodge compared to short-season varieties that have shown to have more harvest losses due to lodging. Finally, if you have a problem with soybean stem borer, you may want to consider planting sunflowers as a trap crop. Evidently the soybean stem borer prefers sunflowers to soybeans.
Ritika Lamichhane
Extension Educator
Nemaha County
July 2024