I Have Green Worms on a Confederate Rose Bush

Hibiscus sawflies attack several hibiscus species, including Confederate rose.

Confederate rose (Hibiscus mutabilis), a widely grown southern shrub, blooms in late summer with 6- to 8- inch funnel-shaped flowers. They emerge white, aging to shades of pink. Green hibiscus sawfly caterpillars are one of the plant's few pests.

Adult Hibiscus Sawflies

Adult hibiscus sawflies (Atomacera decepta) measure less than 1/4 inch long. They are almost entirely black except for the yellow area behind ahead of some species. Their wings are smoky gray. Female sawflies lay eggs along the upper edges of the Confederate rose bush's leaves.

Caterpillars

The newly hatched caterpillars crawl to the leaves' undersides to feed. Telltale signs of their presence are translucent leaf areas where the worms have scrape tissue away. Mature caterpillars are 1/2 inch long and pale green with darker heads. They eat right through the foliage, avoiding leaf veins. A Confederate rose with skeletonized foliage results.

Control

The caterpillars' tiny size makes manual removal difficult. A range of pesticides, including horticultural oil, insecticidal soaps and acephate-, permethrin- or pyrethin-based spray insecticides control the sawflies. Spray the infested plant's leaves thoroughly at a time when no bees or hummingbirds are visiting the flowers. Alternatively, drench the surrounding soil with an imidacloprid-based insecticide in early spring.

References

• University of Florida IFAS Extension: Hardy Hibiscus for Florida Landscapes: Gary W. Knox et al.: October 2008
• University of Arkansas Arthropod Museum: Mallow or Hibiscus Sawfly: Jeffery K. Barnes: June 2005
• Connecticut Agricultural Experiment Station: Hibiscus Problems: April 2007

Resources

• Alabama Cooperative Extension System: Hibiscus - a Plant That Bollms All Year: Dr. Dave Williams