Daylily aphids, Myzus hemerocallis, (Figs. 1, 2) were first reported in Nebraska in 2015, and were noted as fall pests of daylilies in Butler County and surrounding areas. This held true in 2016 as well, but in May 2017 daylily aphids were noted feeding on daylilies in Butler County.
These aphids are of concern because of the damage they do, which can initially result in leaf yellowing (Fig. 3), and subsequent browning and drying (Fig. 4).
Inspect Your Plants
The first sign of daylily aphids is often the cast skins of aphids as they grow. These appear to be white in color and attached to the leaves, usually deep in the foliage near the base of the plant (Fig. 5).
Control of aphids on daylilies will not be as easy as on other plants, as the aphids are deep in the foliage and protected from contact insecticides and biological controls such as lady beetles. Systemic insecticides should provide control however. Examples of insecticide active ingredients with system activity include dimethoate and acephate.
Homeowners are urged to take care when using these products for their personal safety and to be aware that systemic insecticides can also be expressed in floral parts that can also expose visiting bees to the insecticide. Make sure to read the directions on the label and to follow the directions.
Plants severely damaged by fall did not die, however, the severe feeding in previous falls was expected to reduce the carbohydrates in the root systems. This may in turn reduce early season daylily growth the following spring.
Infestations this early in the year are new. Homeowners with daylilies need to monitor and may need to treat when plants begin to yellow if aphids are present.