STRAIGHT FROM THE HORSES MOUTH

Duane A. Lienemann,

UNL Extension Educator,

Webster County

April 20, 2012 Edition
The best place to start this week’s discussion may be an explanation of all these moths flying around. Many call them “Miller” or “Spring” moths. It does seem a little early that these moths are upon us, and it is. It seems that a lot of things are ahead of normal this year and the insects are not an exception. That brings us to discuss what species of moths are these that seem to love to sit in our screen doors, garages and even in our houses, continually annoying cats and humans.
First comes the teaching moment. I would imagine that most people know that a moth is an insect that is related to the butterfly, both being of the order Lepidoptera. What you may not know is that moths form the majority of this order; there are thought to be about 160,000 species of moth (nearly ten times the number of species of butterfly), and amazingly with thousands of species yet to be described. Most species of moth are “nocturnal” species which have a preference for the dark of the night. We have all seen them buzzing porch lights, and yard lights. There are also “crepuscular” species, which means they are particularly active primarily during twilight, or if you prefer - dawn. There are also “diurnal” species which, you probably have surmised by now, are those that fly during the day. They like daylight and are the ones we see fluttering around as we do our day to day activities. From what I can determine our aggravators are army cutworm moths.
Army Cutworm Moths: “Euxoa auxiliaris”, or army cutworm, is commonly found in the Western section and prairies of the United States. The army cutworm is a cyclic or intermittent pest that can cause damage to alfalfa and grain crops in early spring. Damage is caused by the cutworm larvae, which are dingy, light to dark gray caterpillars that often have a lighter gray stripe running the length of the body. Adult cutworms are one of the common “miller” moths seen fluttering around porch lights at night. The good news is that there is only one generation per year and that the moths do very little damage other than being annoying, and of course laying eggs which will eventually become larvae and the next cycle.
Army cutworms have an unusual life cycle that parallels the life cycle of fall grains and other fall annual plants. Adult moths spend the summer at high elevations in the mountains and migrate to rangeland and cultivated fields in August and September. Each female moth then lays from 1,000 to 3,000 eggs in barren or sparsely vegetated fields, especially winter wheat, alfalfa and grasslands. Within a few days, eggs hatch into caterpillars that begin feeding on grasses, weeds, and a variety of crops. Unlike many cutworm species that sever plants at the soil surface, army cutworms climb plants to eat leaves and stems. Feeding continues until cold weather sets in, then the partially-grown caterpillars burrow into the soil for the winter. Caterpillars emerge from the soil, usually in March through April and resume feeding. If no plants are growing, cutworms may migrate up to three miles in search of green feed. Caterpillars feed until they are approximately two inches long and then they burrow into the soil to pupate. Adult moths normally emerge from the soil in April and in June. The moths prefer to feed at night on the nectar of flowering shrubs and trees. This feeding does not harm the plants. As dawn approaches, the millers congregate and may enter homes, garages, barns and sheds in search of resting sites. Narrow cracks or crevices are preferred for these sites, but any protected area is suitable.
Moths, emerging in Nebraska, tend to remain in the area for two to three weeks but may stay for up to six weeks or as long as local plants are flowering. Cool and wet conditions during this time will extend their stay. Hot and dry conditions will encourage the moths to move westward. The moths migrate westward and upward in elevation as they follow the progression in the initiation of blossoming of spring flowering plants. After feeding briefly on nectar provided by these wildflowers they will then migrate back to higher elevations. They are known to travel to mountainous climate regions in late June and early July where they feed at night on the nectar of wildflowers, and during the day they seek shelter under various rock formations. It may surprise you that army cutworms are one of the richest foods for predators, such as brown bears and even grizzly bears, in the mountainous region ecosystem. The moth’s body can have up to 18 percent protein, and from 40-70 percent fat, thus making it more calorie-rich than elk or deer. Grizzly bears in Yellowstone Park have been observed feeding almost exclusively on moths 3 months each summer. You can see these bears picking up or turning over rocks, and reaching with their tongues into cracks and crevices for them. Those insects that survive head back east to start the whole process over. I guess I really never thought much about the journeys of this insect, now I do.
Wheat Diseases & Yellow Wheat: It may interest our wheat producers that Dr. Steven Wegulo, UNL Extension Plant Pathologist, was in south central Nebraska on April 18 and he reported stripe rust. Severity ranged from trace to 70% or higher on lower leaves in hot spots in the southern-most counties. In Adams and Clay counties, severity was mostly trace. Crop growth stage in the southern-most counties was Feekes 10 (boot) in a few fields. The rest of the fields were mostly at Feekes 8 (flag leaf visible) to Feekes 9 (flag leaf emerged). Conditions are currently very conducive to stripe rust development, so it may pay to take a look at your wheat. The real important thing to remember is to watch and protect that flag leaf, as up to 75% of our potential yield is determined there. Flag leaves have started emerging and will continue to do so at an accelerated rate. We still have some yellow wheat fields that are a concern. It may be that we are lacking another nutrient, perhaps sulfur, rather than nitrogen - which would be the logical guess. I am working on that - stayed tuned!
The preceding information comes from the research and personal observations of the writer which may or may not reflect the views of UNL or UNL Extension. For more further information on these or other topics contact D. A. Lienemann, UNL Extension Educator for Webster County in Red Cloud, (402) 746-3417 or email to: dlienemann2@unl.edu or go to the website at: www.webster.unl.edu/home