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Extension Entomology

Month: May 2020

ID to last week’s bug

–by Frannie Miller

 

Brown Recluse – This spider is a brown recluse, but is exhibiting a color shift (usually they have a darker colored abdomen). This can be caused by the diet the spider ate or due to where it is living (notice the lighter colored background). If you are interested in learning more about their life cycle, biology, and feeding habits a good resource can be found at: https://bookstore.ksre.ksu.edu/pubs/MF3133.pdf

 

European Elm Flea Weevil

–by Dr. Raymond Cloyd

We are seeing damage on elm (Ulmus spp.) trees caused by the larvae and adults of the European elm flea weevil (Orchestes alni). Larvae are cream-colored, legless (Figure 1), and located in the mines of leaves. Adults are 3 mm (0.11 inches) in length, red-brown, with black spots or markings on the abdomen or wing covers (Figure 2).

Fig 1. European elm flea weevil larva (Auth–Raymond Cloyd, KSU)

Fig 2. Adult European elm flea weevil (Auth–Raymond Cloyd, KSU)

The mouthpart is shaped-like a snout (Figure 3)

Fig 3. European elm flea weevil adult (note the snout-like mouth) (Auth–Raymond Cloyd, KSU)

since they are weevils and the hind legs are thickened and enlarged, which allows the adults to jump when disturbed. Adults are initially active in May, and after mating, females lay eggs in the large mid-veins of new leaves. Larvae hatch from eggs and tunnel through the leaf as they feed, creating serpentine-like mines that enlarge as larvae mature (Figure 4).

Fig 4. Serpentine mines created by European elm flea weevil larvae (Auth–Raymond Cloyd, KSU)

Larvae eventually transition into a pupal stage, and then adults emerge in May through June. Adults primarily feed on leaf undersides creating small holes on young leaves (Figure 5).

 

Fig 5. Feeding damage caused by European elm flea weevil adult (Auth–Raymond Cloyd, KSU)

Feeding damage caused by larvae and adults will not kill an elm tree; however, extensive feeding damage may ruin the aesthetic appearance. Adults overwinter under loose bark and in leaf litter located under previously infested trees. There is one generation per year in Kansas. Nearly all elm species are susceptible to feeding by the European elm flea weevil; especially Siberian elms (Ulmus pumila) and certain elm hybrids with Asian parentage.

                Management of European elm flea weevil involves maintaining tree health by implementing proper watering, mulching, pruning, and fertilizing practices Insecticides can be used to minimize damage; however, insecticides are difficult to apply to large trees. Contact insecticides must be applied May through June to suppress adult populations. Be sure to read the insecticide label carefully to ensure that “weevils” are listed. Thorough coverage of leaf undersides is important because adults tend to feed on the undersides of leaves. If damage is not extensive, especially on large trees, then there is no reason to apply insecticides. 

Soybeans—Bean leaf beetles

–by Dr. Jeff Whitworth

Bean leaf beetles (fig. 6) overwinter in Kansas as adults. They are usually first found in late winter/early spring in alfalfa fields because as the temperatures start to warm these adults become more active and actually feed a little on alfalfa foliage. However, there are not enough to cause any problems in these alfalfa fields. However, every year they are impressive because of their super ability to detect the very first germinating soybean plants, whether volunteer or planted. They can apparently detect these early plants from many miles away. As these first germinating plants are found by these adult beetles from many different overwintering sites, they can do some quite noticeable leaf feeding damage (fig. 7). These plants are usually mainly on border rows as the adults fly to and start to feed on the first plants they find from distant overwintering sites. These oval/oblong holes can cause considerable concern, especially if only border rows are examined and growing conditions are stressful. Please remember these young soybean plants are very resilient at absorbing this early season defoliation without any subsequent impact on the plants or yield, as long as the defoliation is less than about 50% in the vegetative stages and good growing conditions return. These adult beetles then lay eggs in the soil and around the base of these plants where they hatch and the larvae feed on the roots/root hairs. These adults then emerge in mid-summer and start feeding on new leaves and/or, more problematic, sometimes on the pods.

Figure 6. Adult Bean Leaf Beetle (red color phase)

Figure 7. Damaged Soybean Seedlings (Cody Wyckoff

Alfalfa—-Alfalfa weevil, damage, aphids, lady beetle

–by Dr. Jeff Whitworth

Alfalfa weevil larval feeding damage seems to be almost finished (fig 1.) throughout north central Kansas, for one of the following reasons: some larvae were killed naturally a few weeks ago due to the freezing temperatures, some were killed by insecticide applications, and some have just developed  to the pupal stage and thus quit feeding. There are still a few active larvae (fig. 2) however, most remaining weevils are mature larvae, but there are also a very few younger ones (i.e. note the tiny larva that just hatched, at the tip of the pencil), plus a few pupae and adults.

Figure 1. AW feeding

 

Figure 2 Various stages AW larvae (Cayden Wyckoff)

Aphids are still present (fig. 3), but in tremendously reduced numbers, also probably for the same reasons as the factors that decimated the weevils, but plus–there are significant numbers of lady beetle pupae (fig. 4) and adults (fig. 5). This means there were significant numbers of lady beetle larvae previously feeding on those aphids. Hopefully, these ladybeetles will survive and move to any fields wherever they can find pests to feed on during the rest of the growing season.

Figure 3. Aphid (Cayden Wyckoff)

 

Figure 4. Lady Beetle pupae (Cayden Wyckoff)

Figure 5. Adult Lady Beetle (Cayden Wyckoff)

Many alfalfa fields have already just been/or are currently being, swathed throughout south central and north central Kansas. This should take care of any remaining alfalfa weevil larvae. However, it may allow some stem feeding, often called “barking”, by adults especially under the windrows and may continue until temperatures warm up into the 80’s.

Pests Love the Clutter

–by Frannie Miller

Did you know that May 10 is National Clean Up Your Room Day? A national holiday might help to motivate us to clean, but I am using it as a reminder that cockroaches, ants, mice and other pests thrive in cluttered spaces. It is important to do your part in helping to prevent pests.

Good sanitation goes a long way in preventing pests from living inside your home. Pests occur in our space because we provide them with food and shelter. Clutter, cardboard, and protected spaces provide an environment for pests to eat, sleep and reproduce. Clutter, such as dirty clothes, old newspapers, food wrappers etc. found in a messy room provide a wealth of possibilities for pests. The clutter can even hide signs of the presence of the pest. I know how easy it is to accumulate items, which can contribute to the problem of clutter. Just picking up and putting away one item each day could make a big difference.

Use this date as a reminder to use these integrated pest management strategies to help discourage pests from becoming a problem in your home.

 

  • Make sure to remove anything containing food residues. Food is a good way to attract pests.
  • Stay organized and stop leaving clutter on tables, floors, etc. Clutter incites the company of pests.
  • Clean neglected spaces, such as attics, garages, cellars, and basements.
  • Empty and dispose of trash on a regular basis.
  • Vacuum frequently to remove pests, excess food waste, shed skins, egg cases, and droppings.