Have you noticed that your geraniums and petunias are not blooming (flowering)? Well, the “critter” or culprit causing the problem may be the caterpillar or larval stage of the tobacco budworm (Heliothis virescens). Adults are pale-green to light-brown with the forewing marked with four light wavy bands (Figure 1).
Figure 1: Tobacco budworm adult
The wingspan is approximately 38.0 mm. Adult females can lay between 500 and 1,000 eggs within 2 to 3 days. Caterpillars are 38.0 mm in length when full-grown and vary in color depending on the host plants fed upon. The caterpillars (larvae) may be black, pale brown, yellow, green, and/or red. They may also possess stripes that extend the length of the body (Figure 2).
Figure 2: Mature larva (caterpillar) of tobacco budworm
Furthermore, caterpillars may have small hairs or setae on localized sections of the body. The caterpillars tunnel into buds (Figure 3)
and feed from inside or chew flower petals, which appear ragged (Figure 4).
Figure 4: Tobacco budworm larva (caterpillar) feeding on petals of petunia flower
Damage usually increases during the growing season. Furthermore, caterpillars feeding inside flower buds on developing ovaries will destroy flowers. Be on the look-out for black fecal deposits (“caterpillar poop”) (Figure 5)
Figure 5: Black fecal deposits (“caterpillar poop”) associated with tobacco budworm larva (caterpillar) feeding
on the flower petals or on leaves below the flowers, which is a clear indication that the caterpillars are feeding. Tobacco budworm caterpillars will feed on a number of annual bedding plants besides geraniums and petunias, including: ageratum, chrysanthemum, nicotiana, snapdragon, and strawflower. Ivy geraniums may be less susceptible than other geranium types. The way to deal with tobacco budworm populations is to apply insecticides before the caterpillars tunnel into the buds using materials containing the following active ingredients: spinosad, cyfluthrin, permethrin, or bifenthrin. Be sure to thoroughly cover all plant parts as tobacco budworm caterpillars will also feed on plant leaves.
You can find more information on tobacco budworm feeding on petunia in the following article:
Davidson, N. A., M. G. Kinsey, L. E. Ehler, and G. W. Frankie. 1992. Tobacco budworm, pest of petunias, can be managed with Bt. California Agriculture 46 (July-August): 79.
We have received inquiries regarding cucumber and squash plants wilting and collapsing, and a recent visit to the Manhattan Community Garden (Manhattan, KS) provided evidence that the larvae of the squash vine borer (Melittia cucurbitae) are indeed active inside plants. Squash vine borers feed on squash, pumpkin, cucumber, and muskmelon.
Adults are “clear wing” moths 5/8 inches long. The front wings are covered with scales whereas the hind wings are transparent because they do not have scales. Hind wings have red-brown hairs along the edges. The body is orange-red, with gray bands and three black markings along with orange-red hairs on the abdomen (Figure 1).
Figure 1: Squash vine borer adult
Moths are active during the day with females depositing eggs on the stem near the soil level or on stems or petioles when plants begin to flower. The eggs are red-brown, flattened, 1/30 inches in diameter, and are typically located at the base of plants (Figure 2).
Figure 2: Squash vine borer eggs located at base of plant
A single female is capable of producing up to 200 eggs. Larvae that hatch from eggs are white, with a dark head capsule. Young larvae are 1/4 to 3/4 inches in length and taper toward the end of the abdomen (Figure 3).
Figure 3: Young larva of squash vine borer
Mature or fully-grown larvae are 1.0 to 1.5 inches long (Figure 4).
Figure 4: Mature larva of squash vine borer larval feeding
Larvae that hatch from eggs immediately tunnel into the base of plants. The larvae feed for 30 days in the plant stem, and increase in size as they mature. Typically there is only one larva per stem; however, multiple larvae may be present in a single tunnel in the stem. Mature larvae leave plants and burrow into the soil to pupate by constructing brown, silkened cocoons in which they overwinter. Squash vine borer overwinters as a mature larva in the cocoon that is located 1.0 to 2.0 inches in the soil. In early spring, the adult (moth) emerges from the soil. Squash vine borer has one generation in Kansas.
At this point, squash vine borer larvae are feeding within the internal vascular tissues inhibiting the plant’s ability to take-up water and nutrients; consequently, resulting in sudden wilting of vines and plant collapse (Figure 5).
Figure 5: Plants wilting due to squash vine borer larval feeding
Once the larvae are inside the plant, there is little that can be done to control them or prevent damage. The tunnels inside infested plants are packed with moistened frass (fecal matter) (Figure 6).
Yellow-green sawdust-like frass can also be found around feeding sites at the base of vines or plants (Figure 7)
Figure 7: Frass or fecal matter near tunnel entrance of squash vine borer larvae
,which will be a direct indication that larvae have entered the plant.
Since the larvae are feeding inside the plant there is not much that can be done to kill the larvae; however, there are number of plant protection strategies that can be implemented during the remainder of the growing season, including: sanitation and physical control.
Sanitation: remove and dispose of all wilted plants before the larvae leave and enter the soil. Discard all plant debris such as vines and fruits after harvest.
Physical control: rototilling in fall or spring will directly kill squash vine borer pupae or bring the pupae to the soil surface where they are exposed to cold weather or predation by birds. In addition, the process of deep plowing will bury the pupae deeper in the soil profile thus inhibiting adult emergence. Another technique that may have limited use in large plantings but may be feasible for smaller plantings is to locate infested stems and vines, create slits at the base of the plant, and then use tweezers to remove and destroy the larvae inside. The plant base should then be covered with moist soil, which stimulates the production of secondary vines and/or root growth; thus helping the plant to re-establish.
There is a new up-dated extension publication on squash vine borer (MF3309) that contains current information on plant protection with images of the insect (both adult and larva) and plant damage. You can download a PDF from the following website:
Wheat harvest is completed, or at least real close, across the State. So, it is time to start thinking volunteer wheat control. As wheat producers know, volunteer wheat is very persistent. Every time it rains or the fields are irrigated, another flush or crop of volunteer wheat germinates. Thus, control needs to be just as persistent. Volunteer wheat can be a harborage for most wheat pests, especially bird cherry-oat aphids, Brown wheat mites, English grain aphids, greenbugs, Hessian flies, wheat curl mites, and many of the more common pathogens. Season-long control is always best, but rarely practical. So, volunteer wheat eradication at least 2 weeks prior to planting is the next best management practice.
–by Dr. Raymond Cloyd
There are two new extension publications available: one on squash bug and one on squash vine borer. Both publications contain up-dated information on management, and clear images of the different life stages of the insect pests and subsequent plant damage. The links for both are provided below:
Japanese beetle adults are out in full-force in certain regions of Kansas feeding on one of their favorite host plants…roses. The means of dealing with the adult stage of this insect pest are limited, however, and have been for many years, with the use of insecticides being the primary plant protection strategy. Japanese beetle, Popillia japonica is native to Japan and was first reported in the United States in 1916 in the state of New Jersey. Since then, Japanese beetles have spread throughout the country from Maine to Georgia with permanent establishments in nearly every state east of the Mississippi River and several western states west of the Mississippi River. Japanese beetles are established in eastern and central portions of Kansas and are slowly moving further west. The adult is one of the most destructive insect pests of horticultural plants in both landscapes and gardens. The larvae or grub is a major turfgrass pest in home lawns, commercial settings, and golf courses.
Japanese beetle adults are 9/16 inches long and metallic green with coppery-brown wing covers (Figure 1).
Fig 1: Close-up of Japanese beetle adult.
There are approximately 14 tufts of white hair present along the median of the abdomen (Figure 2).
Fig 2: Japanese beetle adult. Note tufts of white hairs on median of abdomen.
Adult Japanese beetles emerge from the soil and live from 30 to 45 days feeding on plants over a four-to-six-week period. They feed on many ornamental plants including trees, shrubs, vines, herbaceous annual and perennials, and of course—roses. Plant placement in the landscape and volatiles emitted by plants are factors that influence adult acceptance. Furthermore, Japanese beetle adults produce aggregation pheromones that attract individuals (both males and females) to the same feeding location. Adults may fly up to five miles to locate a feeding site; however, they tend to fly only short distances to feed and lay eggs.
Japanese beetle adults feed through the upper leaf surface (epidermis) and leaf center (mesophyll), leaving the lower epidermis intact. They usually avoid feeding on tissue between leaf veins, resulting in leaves appearing lace-like or skeletonized (Figure 3).
Fig 3: Japanese beetle adult feeding damage.
Adults are most active during warm days, feeding on plants that are exposed to sunlight throughout the day, which is likely why roses are a susceptible host plant because they require at least six hours of direct sunlight. Japanese beetle adults also start feeding at the top of plants, migrating downward after depleting food sources. Japanese beetle adults aggregate in masses on rose flowers (Figure 4).
Fig 4: Japanese beetle adults aggregating on rose flower.
Although adult beetles feed primarily on flowers, they will also feed on leaves (Figure 5).
Fig 5: Japanese beetle adults feeding on leaves.
Japanese beetle adults chew holes in flower buds, which prevent flowers from opening or cause petals to fall prematurely. Moreover, adults will consume entire rose petals, and feed on the pollen of fully-opened flowers.
Japanese beetle adult management involves implementing a variety of plant protection strategies, including: cultural, physical, and insecticidal. Cultural involves maintaining healthy roses through proper irrigation, fertility, mulching, and pruning, which are important in minimizing any type of stress; thus possibly decreasing susceptibility. Also, removing weeds such as smartweed (Polygonum spp.) that are attractive to Japanese beetle adults will at least alleviate infestations. Physical is associated with hand-picking or collecting Japanese beetle adults from roses before populations are extensive. The appropriate time to hand-pick or collect adult beetles is in the morning when ambient air temperatures are typically “cooler.” Adults can be easily collected by placing a wide-mouthed jar or bucket containing rubbing alcohol (70% isopropyl alcohol) or soapy water underneath each adult, and then touching them. Adults that are disturbed fold their legs perpendicular to the body, and fall into the liquid and are subsequently killed. This procedure, when conducted daily or every-other-day, particularly after adults emerge, may substantially reduce plant damage. The use of Japanese beetle traps is not recommended since the floral lure and synthetically-derived sex pheromone may attract more adult beetles into an area than would “normally” occur. Adult beetles may also feed on roses before reaching the traps, which increases potential damage.
Spray applications of contact insecticides will kill Japanese beetle adults. Repeat applications will be required; especially when populations are excessive. Furthermore, thorough coverage of all plant parts will increase effectiveness of the application. The insecticide carbaryl (Sevin) and several pyrethroid-based insecticides including those containing bifenthrin or cyfluthrin as the active ingredient may be used to suppress Japanese beetle adult populations. However, since most of these insecticides are also directly harmful to many natural enemies (parasitoids and predators) their continual use may lead to secondary pest outbreaks of other pests including the twospotted spider mite (Tetranychus urticae). Moreover, these insecticides are directly harmful to pollinators (honey bees and bumble bees). Therefore, applications should be conducted in the early morning or late evening when pollinators are less active. In general, systemic insecticides, are not effective because Japanese beetle adults have to feed on leaves and consume lethal concentrations of the active ingredient. If extensive populations are present, then damage to plants may still occur.
The battle or war against Japanese beetle adults requires patience, persistence, and diligence in order to prevent adults from causing substantial damage to roses and other susceptible plants.
For more information on Japanese beetle and other pests of roses consult the following publication:
Compendium of Rose Diseases and Pests (second edition). 2007. APS Press. The American Phytopathological Society, St. Paul, MN.
Green June beetle (Cotinis nitida) adults are actively flying around and “bumping” into people and objects. Adults are 3/4 to 1.0 inches in length, and velvety-green, tinged with yellow-brown coloration (Figure 1).
Fig 1: Close-up of adult green June beetle.
Green stripes with yellow-orange margins extend lengthwise on the front wings. The underside of the body is distinctly shiny and metallic green or gold. Adults fly like “dive bombers” over turfgrass for several weeks in mid-summer. The green June beetle has a one-year life cycle, and overwinters as a mature larva (grub). Adults emerge in late-June and are active during the day, resting at night on plants or in thatch. The adults produce a sound that resembles that of bumble bees. Adults will feed on ripening fruits (Figure 2) and may occasionally feed on plant leaves.
Fig 2: Adult green June beetle feeding on fruit.
The male beetles swarm in the morning, “dive bombing” to-and-fro above the turfgrass searching for females that are located in the turfgrass (they are desperately seeking a mate. Females emit a pheromone that attracts males. Eventually, clusters of beetles will be present on the surface of the soil or turfgrass with several males attempting to mate with a single female (I think this qualifies as an “insect orgy.” Mated females that have survived the experience lay a cluster of 10 to 30 eggs into moist soil that contains an abundance of organic matter. Eggs hatch in about 2 weeks in early August and the young larvae feed near the soil surface. The larvae feed primarily on organic matter including thatch and grass-clippings; preferring soils that are excessive moist. Larvae are 3/8 (early instars) to 1.5 (later instars) inches in length, and exhibit a strange behavioral trait—they crawl on their back (Figure 3) because that they have a constant itch.
Fig 3: Larva (grub) of green June beetle crawling on its back.
Potato leafhoppers continue to be very common in many uncut alfalfa fields. In one field, which was actually flowering, there were more than 40 potato leafhoppers/20 sweeps which exceeds the treatments threshold. Please see the Alfalfa Insect Management Guide for more information on treatment thresholds: http://www.bookstore.ksre.ksu.edu/pubs/mf809.pdf.
This field has serious ‘hopper burn’ already, but timely swathing should alleviate leafhopper pressure.
Another field that was swathed about 3 weeks ago, and at that time had about the same level of potato leafhopper infestation as the above pictured field, has only a trace level of potato leafhoppers now (1 potato leafhopper/20 sweeps).
Soybeans seem to be growing well throughout north central Kansas. Not too many pests have been noted. However, there seem to be some spider mite populations building throughout the south central and north central parts of the state. These need to be monitored, especially if adequate moisture is not forthcoming. Mite populations can expand very quickly and really add stress to plants that are already moisture stressed.
Also, blister beetles are starting to swarm, especially in alfalfa and soybean fields. This swarming behavior is primarily for mating purposes and may involve anywhere from a few hundred to thousands of individuals. They may feed a little while swarming and actually cause plant loss, but only in small areas where the swarming occurs. Thus, treatment is rarely warranted.
