June 18, 2004 No. 15
No, this is not a review of the movie “Holes”. Rather, “Holes” refer to the situation that gardeners are seeing in their bean plants (Figure 1). One should not be hasty in assigning blame to an “innocent bystander” such as a beneficial lady beetle (Figure 2). Rather, two different insect pests are responsible for causing foliar damage in beans: bean leaf beetles and blister beetles.
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| Figure 1 | Figure 2 |
Bean leaf beetles are responsible for “the holes. Bean leaf beetles measure 1/8 - 1/4 inch in length. They are yellowish to reddish in color, and each wing has 3 black spots on their inner margin while the outer margin bears an elongated black marking (Figure 3). When inspecting plants, people may wonder how the few small beetles (that they observe) can be responsible for the extensive feeding damage. In fact, beetles are more numerous than first meets the eye. Because beetles prefer feeding on the undersides of leaves, most go unseen. Furthermore, when leaves are disturbed while inspecting their undersides, beetles go undetected when they drop to the ground. Eventually they move back onto plants and resume feeding.
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Figure 3 |
Bean leaf beetles overwinter as adults. Early in the spring, they feed on various plants/weeds until such time that their preferred host (green beans) become available. Foliar feeding (startling when first seen) is less serious than appears. In fact, the overall amount of foliar feeding is usually over estimated. Also, the continued production of new leaves rapidly compensates for the leaf loss caused by beetle feeding.
Bean leaf beetle larvae may be more responsible affecting bean yields. Beetles deposit egg clusters in the ground around the base of bean plants. Larvae feed on roots. If their populations are high, reduced root systems may decrease water and nutrient uptake, thus causing plants to be stunted. Larvae may also partially or fully girdle plant stems. Thus the cumulative effect of larval feeding damage may result in lower bean production.
Blister beetles are another pest which feed on beans. Blister beetles have voracious appetites and consume entire leaves. Blister beetles are described as “beetles with necks” due to the skinny thorax connection between the head and remainder of the body) (Figure 4). They travel in massive swarms which may “drop in overnight”. If people fail to inspect gardens for several days, they may be surprised to see bean plants completely stripped of leaves. And the blister beetles may be nowhere in sight because just as quickly as they appeared, they up-and-disappear when they move to their next feeding site.
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Figure 4 |
The two most common species of blister beetles encountered in gardens are the ash-grey blister beetle (a soft velvety-grey species) and the striped blister beetle (Figure 5). Currently, ash-grey blister beetles are appearing in light trap catches and have been seen massing on sweet clover along roadsides. So it is very likely that they will eventually make their way into some gardens. Be cautioned that handpicking blister beetles is not recommended ----- as their name applies, they cause blistering due to a liquid irritant which they produce.
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Figure 5 |
Both bean leaf beetles and blister beetles can be controlled with insecticides. It is important to achieve total leaf coverage, especially so for bean leaf beetles which (as stated earlier) prefer to feed on lower leaf surfaces. Various active ingredients are registered for use specifically against bean leaf beetles and blister beetles on beans, or (in general) beetles on beans, and include: carbaryl, malathion, permethrin and rotenone/pyrethrin.
Although not grown as an ornamental, few would dispute the beauty of a field of blossoming potatoes (Figure 6). On a recent (June 10) visit to a local community garden, some potato plants in some plots appeared to be progressing well (Figure 7) although leaves on a few plants did show some minor “shothole” feeding damage (Figure 8) attributable to flea beetles. But plants in many plots were infested with Colorado potato beetle larvae (Figure 9). These pinkish to reddish slug-like larvae have ravenous appetites and are capable of causing major defoliation of plants if allowed to feed unchecked (Figures 10 and 11).
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| Figure 6 | Figure 7 | Figure 8 |
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| Figure 9 | Figure 10 | Figure 11 |
The familiar oval-shaped black and white striped Colorado potato beetle (Figure 12) is a major potato pest throughout the United States. Beetles overwinter buried in the soil and under the litter of trash and debris of old vines. Early in spring, beetles move to potato plants. For a period of 4-5 weeks, each female deposits an average of 500 yellow golden eggs (standing on end) in masses on lower leaf surfaces (Figure 13).
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| Figure 12 | Figure 13 |
Newly emerged larvae begin the feeding cycle, and for the next 3-4 weeks, pass through 4 growth stages (Figure 14). Mature larvae (Figure 15) burrow into the soil where they form chambers in which they pupate (Figures 16 and 17). Newly emerged adults mate, and eggs for the second generation are produced. If potato plants are unavailable, Colorado potato beetles successfully survive on alternate hosts including tomato, egg plant and various weeds including its original host, buffalo burr.
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| Figure 14 | Figure 15 | Figure 16 | Figure 17 |
A couple of methods can be used to control Colorado potato beetles and their larvae. Where but a few plants are being grown, handpicking is an old time method still favored by some people. However where plant stands are more extensive and handpicking is impractical, various insecticides can be used to control Colorado potato beetles. The active ingredients carbaryl, endosulfan, esfenvalerate, permethrin, rotenone/pyrethrin and spinosid. Some horticultural oil formulations are registered for use against the soft-bodied larval stage of “beetle larvae” on selected vegetables including potatoes.
Bob Bauernfeind
First adult western corn rootworm reported (from Cloud County) on June 15, 2004 and first adult soybean stem borer from soybeans (Dickinson County) on June 11, 2004. This is ea. 7-10 days earlier than average.
Jeff Whitworth
Swimming season has started and swimming pools of any size can potentially produce large number of mosquitoes. Here are some steps to make sure that a swimming pool does not become a developmental ground for mosquitoes.
Mosquito larvae develop in standing water and feed on microbes (bacteria, fungi, algae, protozoa). Any swimming pool is a body of standing water and there is not much that you can do about that. Aeration helps but does not completely eliminate mosquito larvae. So, the key step is to keep the pool clean - without bacteria and other microbes. To do that, follow the instruction for sanitation of swimming water in pools. Chlorine works - kills microbes and therefore prevents development of mosquito larvae (because they have nothing to feed on)! There are many products (chlorine tablets) and kits on the market for cleaning and sanitizing swimming pools. It is also a good idea to cover the pool when not in use to prevent contamination (falling leaves, dust, bacteria....) and rain water (diluting the chlorine concentration). But make sure that the cover itself does not collect rainwater and does not become a habitat for mosquito larvae.
There are other good reasons to keep the pools clean: Thousands of people become ill each year from swimming in pools and other recreational waters such as hot tubs, wading fountains, water parks. The main source of illness are bacteria including, Escherichia coli 0157:H7, Shigella spp., and protozoa such as Cryptosporidium and Giardia. These illnesses are spread by accidentally swallowing water that has been contaminated with fecal matter. Again, chlorine works and kills these microbes, I recommend using it!
Ludek Zurek
I have talked to three people this week in southwest Kansas reporting large bat like moths. Apparently there is a migration of Witch Moths which is said to be the largest moth in North America. According to Bagging Big Bugs by Whitney Crenshaw and Boris Kondratieff, it is a tropical insect native to areas of Florida and warmer areas of the Gulf States and ranges south through South America. It has a wing span of up to 6 inches and can sometimes be found as far north as Alaska. A picture of the moth can be found at: http://www.azuswebworks.com/html/blwitch.htm and more pictures and additional information can be found at: http://home.satx.rr.com/txento/witch.htm
Phil Sloderbeck
Contrary to a rumor that appears to be fairly wide spread in some areas of the state, Reldan should still be available to treat wheat going into storage this spring.
RELDAN 4E WILL BE SOLD BY GUSTAFSON UNTIL 12/31/04 TO AUTHORIZED DISTRIBUTORS
DISTRIBUTORS WILL SELL UNTIL 12/31/05, AND TREATED GRAIN WILL BE GIVEN THE OPPORTUNITY TO MOVE THROUGH GRAIN CHANNELS UNTIL 2009-2010
RELDAN 4E – LIQUID:
For direct application to wheat, sorghum, rice, barley and oats as they are transferred into storage.
For treatment of empty storage facilities and modes of transport for grain.
Effective against a broad range of storage insects with limited activity against the lesser grain borer.
When treated at labeled rates, RELDAN treated grain can be used for food, feed or oil purposes.
There is no waiting period from time of application until used for food, feed or oil purposes.
Some malting companies do not accept RELDAN treated malting barley.
Treat insect free grain for best results with RELDAN.
Fumigate infested grain to control existing populations and apply RELDAN for residual protection.
Phil Sloderbeck
Eastern Kansas soybean producers should probably be getting ready to begin scouting for soybean aphids. Aphids were reported last week in Iowa ( http://www.ipm.iastate.edu/ipm/icm/2004/6-14-2004/soyaphid.html ) .
Predictions from John Reese in the Entomology Department and Shawn Hutchinson in the Geographic Information Systems Spatial Analysis Lab indicate that we have a good chance of seeing this aphid about half way across Kansas this year and a slight chance to populations of reach the Colorado border. *** Refer to map.
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If any aphids are found on soybeans we would like to know and possibly receive a sample (dead aphids in alcohol) so we can track the spread of this pest. Send reports and samples to John Reese, Kansas State University, Department of Entomology, 123 Waters Hall, Manhattan, KS 66506 – jreese@oznet.ksu.edu or to Jeff Whitworth jwhitwor@oznet.ksu.edu .
An economic threshold of 250 aphids per plant with the population increasing and plants in the late vegetative or early (R1-R4) reproduction stages is being used by most states in the mid-west. This economic threshold incorporates a seven-day lead-time before the aphid population would be expected to increase to 1,000 aphids per plant, which is the economic injury level and the population size that would be expected to cause economic damage (i.e., yield loss that exceeds the cost of control).
Last year we detected aphids in several counties, but the populations failed to reach damaging levels, probably do to the hot dry weather that we experienced soon after the aphids were detected. What will happen this year hard to predict, and that is why we would encourage producers to monitor fields through out the growing season, and stay alert to potential problems.
More information on the soybean aphid can be found at: http://www.oznet.ksu.edu/entomology/extension/InsectInfo/SoybeanAphid.htm and in the publication “The Soybean Aphid: A new pest in Kansas Soybeans” at: http://www.oznet.ksu.edu/library/entml2/MF2582.pdf
Phil Sloderbeck
The following samples were submitted to the Insect Diagnostic Laboratory from June 3 through June 16, 2004:
6-3-2004, Shawnee County: House fly parts.
6-7-2004, Miami County: Winged Ants.
6-7-2004, Shawnee County: Multicolored Lady Beetle Pupae.
6-7-2004, Riley County: Lone Star Tick off person.
6-8-2004, Riley County: Crab Spider in home.
6-8-2004, Russell County: Leafhoppers in turf.
6-8-2004, Johnson County: Burrowing Bugs in home.
6-8-2004, Riley County: Carpenter Ant in home.
6-8-2004, Crawford County: Negro Bugs on soybean.
6-8-2004, Washington County: Underwing Moth caterpillar on
walnut.
6-8-2004, Barton County: Scarabs on roses.
6-8-2004, Johnson County: Webbing Clothes Moths in warehouse.
6-9-2004, Wabaunsee County: Minute Fungus Beetles, Clover
Mites in home.
6-9-2004, Riley County: Chimney Swift Bug in home.
6-10-2004, Wyandotte County: Soldier Beetle on hosta.
6-10-2004, Wyandotte County: Spittlebug on Lemon Balm.
6-10-2004, Shawnee County: Soldier Beetle on hosta.
6-10-2004, Shawnee County: Variegated Fritillary Caterpillar
on Passion Vine.
6-10-2004, Sedgwick County: Moth in home.
6-14-2004, Barton County: Cornfield Ant in garden.
6-15-2004, Bourbon County: Hackberry Psyllids
6-15-2004, Sedgwick County: Thrip in yard.
6-15-2004, Cheyenne County: Aphids on Cottonwoods.
If there 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,
Phil Sloderbeck
Ludek Zurek
Kansas State University
Extension Specialist
Southwest Research and Extension Center
Medical & Veterinary Entomologist
Garden City
Robert Bauernfeind
Bobby Brown
Extension Specialist
Entomology Diagnostician
Horticultural Entomology
Jeff Whitworth
Extension Specialist
Entomology (Crops)
