Hibiscus Plant Bug, Vol. 5, No. 29
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Niesthrea louisianica
Order: Hemiptera
Family: Rophalidae
These colorful little bugs are most often seen in late summer and fall, congregating on the seed pods of hibiscus, Althea (aka. Rose of Sharon), hollyhock, and other members of the mallow family. Sometimes they are accused of causing plants to stop blooming because the fruiting parts they are found on are dry and brown and it is assumed that the insects have damaged the flower buds and caused them to die before they could bloom. But this is not usually the case. Blooms of plants in this group normally last only a day or two before wilting to reveal the young seed pod. Once seed pods are mature, they naturally dry, turn brown and open to release the enclosed seed. Although these bugs will feed on flower buds, they much prefer to feed on seed pods and the seeds within. Bloom production naturally declines in the fall as the number of dried seed pods increases.
Usually these bugs are feeding on seed pods or are feeding directly on seeds inside pods that have begun to open. Direct feeding often damages seed to the extent that they will not successfully germinate, but this is of little consequence for ornamental plants when seed production is not a goal. In fact, attempts have been made to use these bugs to help control the weedy mallow plant known as velvet leaf in some areas of the country. The control being due to high seed mortality, which means fewer velvet leaf plants next year.
Although hibiscus plant bugs will also feed on flower buds and blooms of ornamental plants, it is relatively uncommon for such damage to be severe enough to prevent blooming or cause significant bloom distortion. Such damage is most likely to occur if large numbers of hibiscus plant bugs occur on plants that have not begun to bloom or are just beginning to bloom, forcing the bugs to concentrate their feeding on the flower buds.
Control: Because hibiscus plant bugs do not usually cause serious damage to flower buds or blooms, control is not normally required. If control is deemed necessary to prevent excessive damage to flower buds, spray with a pyrethroid insecticide, such as bifenthrin, zeta-cypermethrin, cyfluthrin or permethrin, being sure to observed pollinator protection cautions.
Blake Layton, Extension Entomology Specialist, Mississippi State University Extension Service. The information given here is for educational purposes only. Always read and follow current label directions. Specific commercial products are mentioned as examples only and reference to specific products or trade names is made with the understanding that no discrimination is intended to other products that may also be suitable and appropriately labeled.
Mississippi State University is an equal opportunity institution.
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