Plesioclytus morrisi, Wappes and Skelley, 2015

Schnepp, Kyle E., 2019, Notes on the natural history of Plesioclytus morrisi Wappes and Skelley, 2015 and Plesioclytus relictus Giesbert, 1993 (Coleoptera: Cerambycidae), Insecta Mundi 734 (734), pp. 1-8 : 2

Plesioclytus morrisi . Initial observations of P. morrisi were made in June 2018 in Emanuel County, Georgia. While searching for adults of this species in open sandy areas, as indicated by Morris in Wappes and Skelley (2015), individual plants in open sand were noticed ( Fig. 9 ). Realizing this plant was in the right spot but not one of the species mentioned in Wappes and Skelley (2015), they were investigated to see whether larval workings could be detected. The first plant removed had thin stems, likely too small to support larvae the size late instar Plesioclytus individuals might be. The root, however, was larger and appeared to have damage. As more plants were checked, some with “sawdust” were found and some had round emergence holes. A few roots with “sawdust” were broken open and larvae appearing to be a cerambycid were found inside. The roots of some plants that did not have or had not had larvae in them were thin, about the size of the basal stem, indicating the larvae cause the root to swell and grow larger than it normally would. Approximately 15 plants with swollen roots and ejected frass were collected from this site and placed in a collecting net for transport and then left at room temperature and humidity for approximately three weeks. After this period the stems were cut off and the roots were placed in a gallon bag. Most roots contained a single larva, but at least two contained two larvae each. In July 2018, approximately five weeks after being collected, the first adult specimen of P. morrisi emerged, followed by 11 additional specimens the following three weeks. Wappes and Skelley (2015) indicate peak adult activity occurs in May and June; it is possible the cooler indoor temperatures delayed development slightly. Subsequent trips in September 2018 and April 2019 to a similar site in Tattnall County, Georgia, ( Fig. 2 ) resulted in the discovery of more plants with the same larval damage. The plant was later determined to be Polygonum polygamum . Two additional species, Polygonum fimbriatum Elliott and Polygonum pinicola T.M. Schust. and Reveal , in similar sandy situations were also surveyed but no larvae or damage was found.

Figures

Figures 9–12. Root damage and habitat of Plesioclytus. 9) Specimen of P. polygamum with larvae of P. relictus in open sand in Emanuel County, Georgia. 10) Active damage by P. relictus in root of P. polygamum. 11) Blooming specimen of P. polygamum in open sand with larvae of P. relictus. 12) Active damage in stem of P. polygamum containing P. relictus covered by sand.

Figures 1–4. Adult, pupa, and habitat of Plesioclytus. 1) Adult male of P. relictus. 2) Habitat of P. polygamum and P. morrisi in Tattnall County, Georgia. 3) Adult female of P. relictus. 4) Partially dissected root of P. polygamum exposing pupa and adult of P. relictus.