Bristly roseslug sawfly, Cladius difformis (Fig. 1), is a common species of roseslug in Georgia. The larval stages feed on rose leaves and cause extensive damage. Native to Europe, the bristly roseslug sawfly was accidentally introduced to the continental USA, a few decades ago. This roseslug is particularly problematic on rose shrubs in ornamental landscapes. Another roseslug common in the southeastern USA is the common or American roseslug sawfly, Endelomyia aethiops. The curled rose sawfly, Allantus cinctus, is not common in Georgia. These roseslug species are not discussed in this article in detail.

Fig. 1. Bristly roseslug on rose. Photo Credit:  Whitney Cranshaw, Colorado State University,

Description and Life Cycle

Females of bristly roseslug sawfly insert eggs into the leaf petioles mostly in three rows. The eggs hatch and the slug-like tiny larvae move to the lower surface of leaves and feed on the epidermal layer. The larvae of bristly rose slug sawfly have bristle-like hairs on the sides and back, and thus, they are referred to as “Bristly” (Fig. 1); however, it is not readily seen with the naked eye. The late-stage larvae are about ¾ inch long and appear lime-green with the orange head capsules. When ready to pupate, the late-stage larvae drop from the plant and pupate inside a cocoon in the soil. In some cases, they pupate attached to a plant. The emerging adults are black wasps about ½ inch long (Fig. 2). The antennae of females are narrow and elongated (Fig. 2), whereas the base of male’s antennae are comb-like.

Fig. 2. Adult bristly roseslug on rose. Photo Credit:  Whitney Cranshaw, Colorado State University,

Bristly roseslug sawfly undergoes multiple generations during the growing season. Rose shrubs are susceptible to damage from the spring to the end of fall. Each new generation produces extensive defoliation of the rose plants as the density of roseslugs increases through the growing season. The overwintering stage of bristly roseslugs is pupae, which overwinter inside earthen cells. The American roseslug and common curled roseslug have one and two generations, respectively, each year.


The bristly roseslug larvae are the destructive stages of the bristly roseslug sawfly. The early instars of bristly roseslug sawfly scrape the surface from the underside of leaves without feeding on the entire tissue. This feeding behavior leaves a layer of epidermal tissue on the upper leaf surface, which appears as white patches or spots referred to as “windowpanes” (Figs. 3 and 4). Eventually, the white areas collapse, and holes appear on the leaves. As they grow larger, they feed on the interveinal areas of leaves that appear “skeletonized” with only the mid-rib and veins remaining (Fig. 5) because the late stages of larvae feed from the inside and margins of leaves. This feeding initially causes large holes. Leaves drop when infestation is high (Fig. 5).

Fig. 3. Bristly roseslug feeding on the lower surface of rose leaves (white arrow), which eventually become holes (black arrows). Photo Credit:  Whitney Cranshaw, Colorado State University,
Fig. 4. Windowpane symptoms on upper leaf surface after bristly roseslug feeding on lower surface of leaves of rose (white arrow) which eventually become holes (black arrows). Photo Credit:  Whitney Cranshaw, Colorado State University,
Fig. 5. Extensive skeletonization and leaf drop symptoms on rose. Photo Credit:  Whitney Cranshaw, Colorado State University,

Host Range

Bristly roseslug sawfly primarily attacks wild and managed roses.


Feeding activity can be monitored using visual evaluation. On roses, feeding initiates in April and continues until October before frost occurs. Larvae are found on the lower side of the leaves.


Cultural practices, such as hand-picking larvae and destroying them, can help reduce roseslugs on rose plants. Irrigating plants with high water pressure thrice a week could dislodge some roseslugs off from affected plants. Because bristly roseslug sawfly pupates in earthen cells, tilling the soil around or between rose plants multiple times during the growing season may destroy pupae in the soil. Bristly roseslug sawfly overwinters as pupae. Tilling practice during late fall may kill the overwintering pupae and reduce their densities in the following growing season. There is limited information on effective biological control agents, such as predators and parasitoids on bristly roseslug larvae.

                Horticultural oils, neem oil, and insecticidal soap are effective for larval control. However, these products do not have residual activity, so repeated applications may be necessary for desirable control. Foliar application of insecticides, such as pyrethroids (cyfluthrin, deltamethrin, lambda-cyhalothrin), neonicotinoids (acetamiprid, dinotefuran, imidacloprid), spinosad, spinetoram+sulfoxaflor, and chlorantraniliprole, are also effective on larvae. Drench application of dinotefuran and imidacloprid in the spring can reduce larval densities. Ensure the insecticide solution is directly applied to the soil after removing the mulch (if applicable). Following the label instructions before applying any chemical insecticides is critical, as improper applications can cause insecticide drift and unintended exposure to non-targets, including pollinators. It’s important to avoid applying insecticide directly to plants in bloom to protect pollinators. BT (Bacillus thuringiensis) based products and their strains are ineffective on bristly roseslug.


Anonymous. No Date. Pests in Gardens and Landscapes, UC IPM, Statewide IPM Program.

Baker, J. 2021. Bristly Roseslug. NC State Extension Publications.

Bristly Roseslugs Continue to Cause Damage. Boggs, J. 2016. Bug Bytes, The Ohio State University Extension.

Rose sawflies (roseslugs)—Allantus cinctusCladius difformis, and Endelomyia aethiops.

Nixon, P. 2010. Bristly Rose Slug.