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Extension Entomology

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Sorghum Update – (chinch bugs, corn leaf aphids, corn earworms)

–by Dr. Jeff Whitworth and Dr. Holly Schwarting

 

Chinch bugs continue to be very active in both corn and sorghum throughout north central Kansas.  Both nymphs and adults are present.

 

Many adults are still mating, which indicates that there are more eggs, nymphs, and adults yet to come.  One consolation relative to the numerous chinch bugs in sorghum fields is that the four spotted egg eater, Collops quadrimaculatas, seems to be plentiful as well.  They have been collected in samples while sweep sampling alfalfa and are also present in sorghum fields.  These little beetles are predacious on insect eggs, and it has even been reported that they feed on chinch bug eggs.  Not sure they will be able to provide a great deal of control on chinch bug populations but it sure can’t hurt!

 

Corn leaf aphids are also very plentiful throughout north central Kansas.  These aphids usually feed on developing corn tassels and silks, but probably are more commonly associated with, or at least noticed in, whorl stage sorghum.  These aphid colonies sometimes produce enough honeydew, and it is so sticky, that often the sorghum head gets bound up in the whorl and therefore doesn’t extend up properly.  These colonies are not usually dense enough on a field-wide basis to justify and insecticide application.  These plentiful aphids are also serving as a food source for many predators, i.e. lady beetles, green lacewings, etc.

 

 

Corn earworms are still plentiful in corn but as they mature, pupate, and become adults they most likely will migrate to sorghum to feed on developing kernels (between flowering and soft dough), and soybeans where they will feed on developing beans within the pods.

For more information on sorghum and soybean pest management, please consult the KSU Sorghum Insect Management guide: https://www.bookstore.ksre.ksu.edu/pubs/mf742.pdf

And the KSU Soybean Insect Management Guide: https://www.bookstore.ksre.ksu.edu/pubs/MF743.pdf

 

 

European Elm Flea Weevil

–by Dr. Raymond Cloyd

   

We are seeing damage on elm (Ulmus spp.) trees caused by the larval stage of the European elm flea weevil (Orchestes alni). Larvae are cream-colored, legless (Figure 1),

Figure 1. European elm flea weevil larva

and found in the mines of leaves. Adults are 3.0 mm in length, red-brown in color with black spots or markings on the abdomen or wing covers (Figure 2).

Figure 2. Adult European elm flea weevil.

 

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

 

Figure 3. European elm flea weevil adult (note the snout-like mouth)

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. Eggs hatch into larvae that tunnel through the leaf as they feed (which is occurring now), creating serpentine-like mines that enlarge as larvae mature (Figure 4).

Figure 4. Serpentine mines created by European elm flea weevil larvae.

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

Figure 5. Feeding damage caused by European elm flea weevil adult.

 

The feeding damage caused by both the larvae and adults will not kill an elm tree; however, extensive feeding may ruin the aesthetic appearance. Adults overwinter under loose bark and in leaf litter 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 proper tree health by means of watering, mulching, pruning, and fertilizing. Insecticides may be used to minimize damage; however, insecticides may be difficult to apply to large trees. Insecticides must be applied in May and June in order to suppress adult populations. A number of insecticides may be used including: acephate (Orthene), imidacloprid (Merit), or carbaryl (Sevin). However, if damage is not extensive, especially on large trees, then there be no rationale for using insecticides. For more information regarding European elm flea weevil management contact your county or state extension specialist.

 

 

 

 

 

BE ON THE LOOK-OUT FOR GOLDENROD SOLDIER BEETLES

–by Dr. Raymond Cloyd

If you haven’t noticed yet, hordes of goldenrod soldier beetle (Chauliognathus pennsylvanicus) adults are feeding on goldenrod (Solidago spp.) and other flowering plants such milkweed (Asclepias spp.). Adults are extremely abundant feeding on the flowers of chive (Allium Schoenoprasum), and can also be seen feeding on linden trees (Tilia spp.) when in bloom. In fact, adults may be observed both feeding and mating (occasionally at the same time). The goldenrod soldier beetle is common to both the western and eastern portions of Kansas.

Figure 1 Adult Goldenrod Soldier Beetle.pptx

Adults are about 1/2 inch (12 mm) in length, elongated, and orange in color with two dark bands on the base of the forewings (elytra) and thorax (middle section). They are typically present from August through September. Adult soldier beetles feed on the pollen and nectar of flowers, but they are also predators and may consume small insects such as aphids and caterpillars. Flowers are a great place for the male and female soldier beetles adults to meet, get acquainted, and mate (there is no wasting time here). Soldier beetle adults do not cause any plant damage. Sometimes adults may enter homes; however, they are rarely concern. The best way to deal with adults in the home is to sweep, hand-pick, or vacuum.

Figure 2 Adult Goldenrod Soldier Beetles Mating

Adult females lay clusters of eggs in the soil. Larvae are dark-colored, slender, and covered with small dense hairs or bristles, which gives the larvae a velvety appearance. Larvae reside in the soil where the feed on grasshopper eggs; however, they may emerge from the soil to feed on soft-bodied insects and small caterpillars.

Figure 3 Adult Goldenrod Soldier Beetles Feeding

Leafhoppers in Alfalfa

–by Dr. Jeff Whitworth and Dr. Holly Schwarting

Alfalfa can be kind of a forgotten crop during this very busy time of year.  Most growers are busy planting sorghum, soybeans, sunflowers, and/or harvesting wheat, working wheat ground, etc.  This year, so far, has been a rough one for swathing and baling alfalfa.  Now, there are substantial infestations of potato leafhoppers, both adults and nymphs.  Potato leafhoppers can be quite damaging from now until fall.

Leafhopper adult

Leafhopper nymph

 

Both nymphs and adults feed by sucking juice from the plant and in so doing inject a toxin into the plants.  This can cause serious yellowing of the leaves, and even stems, if it continues for very long.  Generally, swathing and hay removal will disrupt this feeding and remove the leafhoppers from the fields.  They rarely re-infest fields after this physical removal or after an insecticide application, if that is justified.  If swathing is possible within the next 7-10 days, that should take care of the potato leafhopper problem.  However, be sure to keep scouting these fields as the damage caused by potato leafhoppers usually occurs much before the yellowing is noticed.  This feeding damage is cumulative – the stressed plants don’t seem to regain their original vigor and therefore don’t ever yield as much tonnage as expected.

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