What’s New in Entomology: West Central Nebraska

2019 Crop Production Clinic Proceedings

What’s New in Entomology: West Central Nebraska

New Nebraska Pest in 2018

Soybean gall midge
Figure 1. At the plant level, darkened stems indicated infestation, removing outer tissue reveals soybean gall midge maggots (Photo by Justin McMechan)
  • Soybean gall midge was first documented in Nebraska in 2011 in a few isolated fields in the northeastern part of the state. This insect has historically been considered as a secondary pest of soybean plants that have been mechanically damaged or infected by a plant pathogen, typically showing up in mid- to late August. In 2018, a larger number of fields through the eastern part of the state were infested earlier in the season (late June) than in previous years.


    Fields with significant levels of damage had a high number of dead plants at the field edge; damage decreased moving toward the center of the field. Little information is available on soybean gall midge. Genetics and morphological comparisons indicate that it is a new species within the genus Resseliela. More

Regional Pest Updates

  • As in previous years, western corn rootworm was a problem in west central Nebraska in 2018 in fields planted to continuous corn. Resistance to pyrethroids as well as resistance to Bt protein Cry3Bb1 (Yieldgard Rootworm) with cross-resistance to mCry3A (Agrisure RW) and eCry3.1Ab (Agrisure Duracade) is a growing concern. Resistance to Cry34/35Ab1 (Herculex CRW) has been recently reported in Iowa; although this trait still performs well in most of Nebraska, proper stewardship is needed. Utilizing a variety of management tactics as well as varying insecticide modes of action can help to provide adequate pest control, as well as slow down the development of resistance. More
  • The 2018 season was an interesting year for western bean cutworm. Flight patterns in North Platte were similar to those of 2017, peaking on July 16, 2018 with 324 moths per night. Moth flights were highest and earliest in south central Nebraska, peaking at Clay Center on July 8, 2018 with 1368 moths per night. There were some reports of high numbers of moths caught in pheromone traps near fields that had very low numbers of egg masses. This could be due to the strong preference of moths to lay their eggs on specific growth stages of corn (late whorl to early tassel). More
Corn earworm larva
Figure 2. Corn earworm larva in ear (Photo by S. Daniel)
  • Corn earworm activity saw an increase in 2018 with over twice as many moths captured in the North Platte black light trap compared to last year (733 in 2017 vs. 1793 in 2018). This corresponds to a rise in field observations of larvae in corn fields as well as other crops, including chickpeas (garbanzo beans). With the increase in adoption of pulse crops like chickpeas in southwest Nebraska, this is a pest-crop interaction to be looking out for. Also see CPC Proceedings article on Lepidopteran Pests of Corn Ears.
  • Wheat stem sawfly continues to be an important pest of wheat in Nebraska. All Panhandle counties west of Cherry, Grant, Arthur, and Keith are at high risk. Of particular risk are those production systems that are no-till and wheat/summer fallow/wheat crop rotations. Wheat acres in close proximity to such cropping systems are also at high risk for increased sawfly abundance. Additionally, the wheat curl mite, with the three wheat viruses that it transmits, poses a high level of risk to wheat-growing areas that had pre-harvest hail events. To better understand this dynamic between hail, wheat viruses, and wheat, please see the “Wheat curl mite time machine.”
  • In alfalfa, it is important to be aware that alfalfa weevil has the potential to cause increased damage after the first cutting as a result of both larval and adult feeding.  This weevil generally overwinters as an adult, however, eggs are surviving the winter in some areas, potentially due to milder winter temperatures in recent years. More
  • The Dectes soybean stem borer is a longhorn beetle native to North America east of the Rocky Mountains. This beetle has shifted its host from cultivated sunflower to soybean and was first found infesting soybean in Nebraska near the Kansas border in 2000. Dectes has been moving through south central Nebraska toward the west central portion of the state with confirmed presence in North Platte and McCook since 2015. More
Map of Japanese beetle distribution
Figure 3. Japanese Beetle Distribution as of 2017.
  • Native to Japan, the Japanese beetle is an invasive species that was first found in the United States in 1916 near Riverton, New Jersey. Since then, this scarab beetle has spread westward into additional states, including Nebraska. Adults have a wide host-range and will feed on soybean leaves and corn tassels while the larvae, or grubs, feed on the roots of turf grasses. As of 2016, confirmed infestations of this beetle have been found as far west as Lincoln County. More
  • Due to a cooler and wetter season, there were fewer instances of spider mite and grasshopper infestations in 2018. Because spider mites tend to thrive on drought-stressed plants, the 2018 season provided fewer opportunities for their populations to reach significant levels. Grasshoppers tend to feed on weedy plants bordering irrigated crop fields and then move into the crop when the bordering vegetation dries later in the season. The cooler and wetter weather of 2018 provided ideal conditions for border habitat to remain and support grasshopper populations which reduced grasshopper migration into crop fields. More on grasshoppers. More on spider mites.
Emerald ash borer
Figure 4. Emerald ash borer adult (Photo courtesy of www.arborday.org)

National Pest Alerts

  • While it has not made its way to the west central area of Nebraska, the emerald ash borer was confirmed in Lancaster County in August 2018. This beetle is a pest of ash trees and is now present in six counties of eastern Nebraska: Dodge, Washington, Douglas, Sarpy, Cass and Lancaster. The best way to prevent the spread of this pest is to keep firewood local and refrain from transporting it. More
Adult spotted lanternfly; photo by Lawrence Barringer
Figure 5. Adult spotted lanternfly (Photo by Lawrence Barringer)
  • An invasive species native to China, India, and Vietnam, the spotted lanternfly was first detected in Pennsylvania in 2014. While this insect is currently restricted to a few eastern states (Pennsylvania, New York, Delaware, Maryland and Virginia), it does have the potential to spread. The host plants of this insect include grape, apple, plum, cherry, peach and pine. If this pest were to reach Nebraska it could cause significant damage to apple orchards in the east as well as the vineyards throughout the state. More