Origin:
This may be a native species that is found in the eastern half of the U.S.
Biology:
This wasp is a pest on rose mallow and many hybrids of other ornamental hibiscus that are native plants in the southern U.S., but which often are planted as ornamentals in other regions of North America. The female wasp deposits eggs in short rows along the margins of leaves, leading to brown spots at this point on the leaf. The larvae then feed in clusters on the undersides of the leaves, feeding only on the soft tissue and not the veins and leading to skeletonizing of the leaf. This feeding begins in late spring and multiple generations are likely. The life cycle from egg to adult is about 1 month, with the larvae pupating on the lower stems or in the soil below.
Identification:
The adult wasp is about 3/16 inch long and solid shiny black with the top of the thorax dark red. The abdomen joins to the thorax without a thin waist and the sides of the abdomen are parallel. The larva is similar to a moth larva but has 6 pairs of prolegs along the middle of the body rather than the 5 pairs found on moth larvae. They are green on top with yellow sides, have a black head and black spots on the thorax behind the head, and have 6 short black tubular glands along the margin of each body segment.
Characteristicts Important to Control:
Insecticides are effective but must be directed to the lower surfaces of the foliage. Contact insecticide sprays can be used or a soil-applied systemic can be applied in advance of the presence of the damage on the leaves. The use of horticultural oils or soaps will also be effective but must be applied so that the larvae are thoroughly coated with the spray.
