October 29, 2004 No. 30
Recently, many people have been bothered by aggregations of ladybeetles both outside and inside their residences. The culprit is the Multi-colored Asian Lady Beetle , Harmonia axyridis Pallas (Fig. 1). The beetles vary greatly in coloration (yellowish orange to red) and spotting pattern (many or none, Fig. 2) so the key to recognition is the black ‘W’ on the part of the body behind the head. This insect is actually an invasive species that is native to Asia, although it contributes considerably to control of many pest aphids in agricultural crops. The probable reasons we are seeing so many more than usual this year are the wide-spread and abundant soybean aphid populations we saw state-wide this summer. In fact, the cool, damp weather this summer favored large populations of many aphid other species as well and the Asian ladybeetle is highly polyphagous so it can feed on virtually all of them, hence the large populations.
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| Asian Lady Beetle | Different pattern of spots |
The aggregation behavior is brought about by the shorter days and cooler weather in fall. Adult beetles cease reproduction and display this behavior as they prepare to overwinter. In their natural habitat, they would form these aggregations under rocky outcroppings and enter caves in mountainous regions. In an urban setting, they follow geographic topography to hill tops and use other olfactory and visual cues (such as color contrasts and outlines) to orient to sites that appear suitable for hibernation. Depending on the color of your house and its surrounding topography, you could have large aggregations or none at all. On warm winter days they often become active and swarm together on the walls of buildings with good sun exposure, particularly those with white surfaces.
If Asian ladybeetles are entering your house, exclusion is the best prevention. These are reasonably large insects, (although some can be quite small if they fed little as larvae) so it is usually effective to caulk all cracks and crevices around windows and doors. If you have clusters of beetles inside your house, a vacuum is the easiest way to collect them and dispose of them. They are not protected and their pest status is now considered to sometimes equal or exceed the benefits they provide in crop protection. Some people have allergic reactions to them and large infestations will seriously soil and stain walls and furniture.
J.P. Michaud
Reports were received this week from north central Kansas of this mite causing noticeable damage to wheat fields.
This mite is dark brown to nearly black in color, with conspicuous reddish-orange legs. Its front legs are longer than the others, although not as noticeable as with the brown wheat mite. Other unique features are an reddish-orange anal pore on the top of the abdomen and the presence of two tarsal claws on the end of each leg. The small size of these mites may require viewing under a 10 x hand lens, or preferably a microscope, to distinguish some of these features.
During daylight hours, winter grain mites can be found around the base of plants or hiding just under the soil surface. They thrive in cool, moist weather and retreat deeper into the soil under hot, dry conditions. Fields with loose, sandy or loamy soils are more at risk than those with hard, clay soils. Significant infestations are ordinarily confined to central Kansas.
The mites feed on the plants mostly at night, puncturing individual cells and causing the leaves to take on a silvery-gray appearance. Leaf tips may turn brown. Young plants are most susceptible and may become stunted, producing little grain. Control may be necessary if large portions of a field show symptoms and mites appear abundant in relation to the amount of wheat plant growth. Since fall populations develop from over-summering eggs laid the previous spring, problems are worse in continuous wheat and crop rotation is preventive to some degree, although field borders may be affected when mites migrate from wild grasses.
This seems a little early to be getting reports of serious damage from this pest but the recent cool damp weather may be getting things kicked off a little early. Making a decision on whether or not to treat for this pest is mostly a judgment call based on the severity of the feeding and percent of field that is being damaged. Having noticeable damage this early is troublesome in that the mites are likely to be active for several more weeks. However populations can sometimes disappear after a heavy rain. We really don’t have treatment thresholds for this pest since populations can be so unpredictable.
Treatment options are listed in our Wheat Insect Management Guide http://www.oznet.ksu.edu/library/ENTML2/MF745.PDF or on our web site at http://www.oznet.ksu.edu/dp_entm/extension/InsectInfo/Wheat/Winter%20Grain%20Mite.html
Phil Sloderbeck
Several calls have been received in the last few days concerning household invaders. In addition to the Asian lady beetles mentioned above. Millipedes and hackberry nipple gall psyllids have been reported to be present in heavy numbers in some locations. The millipedes were being called wireworms, and the psyllids were thought to be flies, which can make looking up control information a little difficult.
If you get reports of wireworms crawling around inside or outside homes, ask if they have numerous legs. If so then they are probably millipedes. Millipedes normally live outdoors where they feed on damp and decaying wood and vegetable matter, as well as tender roots and green leaves. Their slow-crawling, rounded bodies have two pairs of legs on most body segments. They are generally brownish in color and about 1 to 1 1/2 inch in length. More information on millipedes can be found at: http://www.oznet.ksu.edu/library/entml1/Milliped.pdf
If you get reports of small flies swarming around, covering window screens, ask if there are any hackberry trees in the neighborhood. If so, then put the critters under a magnifying glass and see if they look like tiny cicadas. If they do, then what you probably have are hackberry nipple gall psyllids. The adult is about 1/8-inch long with four transparent wings, prominent eyes, and a body that tapers from front to rear. Psyllids overwinter wherever they can find shelter in buildings and crevices of trees, etc. The immatures develop on hackberry leaves during the spring and cause formation of the familiar nipple galls on the undersides of the leaves. Adults reach maturity and emerge from the galls in the fall just before leaf drop. More information can be found at: http://www.oznet.ksu.edu/library/entml2/mf957.pdf
Phil Sloderbeck
The following samples were submitted to the Insect Diagnostic Laboratory from October 1 through October 27, 2004:
10-1-2004, Shawnee County: Blowfly larvae.
10-1-2004, Shawnee County: Tiphiid Wasp in home.
10-1-2004, Labette County: Indian Meal Moth larvae in home.
10-1-2004, Shawnee County: Soldier Fly larvae in compost
pile.
10-4-2004, Osage County: Weevil larvae in school classroom.
10-8-2004, Meade County: Dark Winged Fungus Gnats.
10-8-2004, Sedgwick County: Thrips on Ficus.
10-8-2004, Butler County: Humpbacked Flies in bee hive.
10-8-2004, Labette County: Winged Ants in yard.
10-12-2004, Riley County: Click Beetle larva.
10-13-2004, Saline County: Sawtoothed Grain Beetles/Dung
Beetles in pasture/feed.
10-15-2004, Harvey County: Yellowjacket Wasps in yard.
10-15-2004, Wyandotte County: Carpet Beetles, Hister Beetles.
10-18-2004, Osage County: Snails in yard.
10-20-2004, Shawnee County: Yellow Ants around house.
10-22-2004, Riley County: Greedy Scale on Cotoneaster.
10-27-2004, Nemaha County: Black Assassin Bugs in home.
If there are any questions regarding these samples or about the identification of any arthropod please contact the Insect Diagnostician at 785-532-4739 or at bbrown@oznet.ksu.edu.
Bobby Brown
Brand names appearing in this publication are for product identification purposes only. No endorsement is intended, nor is criticism implied of similar products not mentioned.
Sincerely,
J.P. Michaud
Bobby Brown
Assistant Professor of Entomology
Entomology Diagnostician
Kansas State University
Agricultural Research Center - Hays
Phil Sloderbeck
Kansas State University
Southwest Research and Extension Center
Garden City
