Endelomyia aethiops and Allantus cinctus

The term roseslug or roseslugs refers to a couple different species of sawfly caterpillars found on rose. The roseslug (Endelomyia aethiops) may be found on the same plants as the curled rose sawfly (Allantus cinctus). The roseslug, E. aethiops, is found in British Columbia as well as the United States, and is thought to be a native species The roseslug was first identified as a pest in Cambridge, MA in gardens in 1831 (Chittenden, 1908). According to Chittenden, 1908, "By 1840 it had become so great a nuisance that a premium of $100 was offered for the most successful method of destroying it (Harris)". Rose species are their only hosts, and females lay eggs in individual pockets on the edges of leaves. This is done with the female's ovipositor (egg laying device) which cuts a pocket between the leaf surfaces into which the egg is inserted. Hatching occurs 10-14 days after eggs are laid. Newly hatched larvae begin to feed by skeletonizing the upper surfaces of leaves. The roseslug larvae (caterpillars) are approximately 1/2 inch long when mature, and complete their skeletonization feeding at that time, after approximately 5-6 weeks of feeding. During the day, larvae rest on the undersides of leaves. Once ready to pupate, they leave the plant and enter the soil to create a cell within which they overwinter. This species of roseslug's larvae may all be done feeding and in the soil by approximately July. They remain in their winter cells until the following spring, at which time pupation occurs. A single generation of E. aethiops occurs per year. Adults are dark in color (deep, shiny black) and wasp-like with four smokey colored wings. Adult females are approximately 1/5 inch long, with males slightly smaller.

The curled rose sawfly, Allantus cinctus, is approximately 0.75 inch long at the time the caterpillar is fully mature. This species is likely an accidental introduction from Europe, first viewed as a pest near Boston, MA in 1887 (Chittenden, 1908). Because their caterpillars are larger than those of the roseslug, it only takes a few of them to seriously damage plants. The curled rose sawfly does not often occur in large populations, yet for the aforementioned reason they can still be significant pests. Caterpillars of this species not only injure plants by feeding on their leaves, but they also bore into the pith of twigs, which can kill stems and act as an area for fungal pathogens to become introduced. Caterpillars of this species will skeletonize the leaves and are eventually capable of eating the entire leaf except the main vein. Boring into the pith of the twig, especially pruned twigs, occurs when the insect is ready to pupate. It is possible that two generations of the curled rose sawfly can occur per year, and in some locations, three may occur. Caterpillars of this species are green on their backs, with abdomens marked with white spots. The head of the caterpillar is yellow in color with a dark brownish stripe down the middle, and with black eye spots. Caterpillars may be found coiled when at rest. Adults are approximately 3/8 inch long, with nearly transparent wings and a shining black abdomen with a wide band in the middle. Adult emergence occurs some time in May. Eggs are laid singly on leaf undersides in groups of 3-7. Historically, adults had also been observed in again in Boston, MA in July (Chittenden, 1908). Other species of sawflies with similar habits may be found on similar host plants in different geographic locations.