Pest Control in the Northern Plains: Chrysanthemum laceworm

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In the final months of the gardening season, gardeners expect to finally see the flowers of autumn perennials. Unfortunately, this is also evidence that we might find that chrysanthemum laceworms have been feeding on these plants throughout the summer.

Target plant

There are about 140 species of lace insects (dyeing) Found in North America and feeds on a variety of plant materials. Most species prefer a host plant or plant family. Adult lace bugs are usually 1/8 to 3/8 inches in length. Chrysanthemum lace bug (Enoki mushroom) Feeds on Asteraceae plants, including many autumn bloomers. chrysanthemum (chrysanthemum Genus and cvs., area 5-9), yellow flower (Solidago Genus and cvs., regions 3-9), Asters (Cross bacteria Genus and cvs., area 4–8), sunflower (sunflower Genus and cvs., regions 3-9), Black Eyed Susan (Coneflower Genus and cvs., Zones 3–11), and Ball thistle (Hedgehog Genus and cvs., Zones 3-8) are just a few late-season perennials that are vulnerable to chrysanthemum lace insects. They feed on the underside of the leaves and are usually overlooked, and the damage caused by their eating does not become obvious until their numbers reach their peaks in the middle and late summer.

Yellow flower before aster
This “purple dome” aster (Neoanglia “Purple Dome”, Area 5–8) and “Fireworks” Golden Chrysanthemum (Solidago “Fireworks”, zones 4-8) are two popular autumn bloomers, which are the main target plants for chrysanthemum lace insects. Photo: Marian Newcomer

damage

Adult lace bugs and spiny dark nymphs feed by inserting needle-like mouths into leaf tissue and sucking chlorophyll and nutrient-rich sap from plants. Their food produces small, mottled spots on the upper surface of the leaves, which are white, yellow, or chlorotic. Hiding under the leaves can protect lace insects from weather and natural enemies. Lace bug damage can be detected by observing the premature leaf shedding and leaf discoloration, with dark brown spots and stains on the bottom of the leaf. You can also visually spot the small insect itself.

Leaves are laced and damaged by bugs
These bitter cherries (Virginia Lee, Area 2-7) The leaves are destroyed by lace insects. Although this is the work of different kinds of lace bugs, the damage of chrysanthemum lace bugs looks very similar. Photo: Whitney Cranshaw, Colorado State University, Bugwood.org

prevention

The plants can be protected by checking for the presence of lace bugs in late spring and using organic controls before large areas of damage occur. Lace bugs are more likely to feed on plants located in hot, dry, and sunny environments, causing their activities to fluctuate with climatic conditions. Using compost and mulch to keep the soil evenly moist is a technique to combat lace insect activity. Creating a diversified rather than monocultured landscape garden will help reduce the spread of this insect because they restrict their diet to specific plants. And because they hide under leaf fragments in winter, a good spring cleaning in the garden will help reduce the number of lace bugs by removing overwintering eggs, nymphs, and adults.

treatment

Once the lace bugs are identified, it is not difficult to control them. The high-pressure water spray directly under the leaves will knock down the wingless nymphs, and then they will not be able to return. Natural enemies such as ladybugs, parasitic wasps, assassin bugs, pirate bugs, lacewing larvae and various spiders help to control the population.

Neem oil, pyrethrin spray and insecticidal soap are all non-residual organic products that effectively control lace insects. From the spring when the nymphs first appear, the underside of the affected leaves must be thoroughly coated with the product. Repeated application is necessary to achieve effective control. These products have few negative effects on humans or pets; however, people should only use them on affected plants to limit contact with non-target insects. Although broad-spectrum insecticides are effective, they should be avoided unless necessary.

Plant selection is important

When designing your garden, choose plants that are healthy, hardy and adapted to the area.Plants are Native to the area It is usually built to thrive under our specific conditions, and robust, healthy plants can more easily resist the attack of lace bugs. Careful planning of various plants can not only protect your garden from this insect infestation, but also reward you with a wider variety of colors, textures, and seasonal interest.

Please contact your local extension service for more information on how to control this pest.

— Marti Neely, FAPLD, owns and operates Marti Neely Design and Associates in Omaha, Nebraska.





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