Neolasioptera rostrata Gagne

This species forms galls in receptacles of both male and female flowers (Gagne and Boldt 1989). It is widespread in the United States, from Maryland, Florida, Texas, and New Mexico where it occurs on B. glomeruliflora, B. halimifolia, B. salicina, and B. neglecta. It also occurs in the Dominican Republic on B. myrsinities (Gagne and Boldt 1989), and R E. Boldt has found it also in Argentina on B. pingraea and B. spartioides (Gagne 1994).

Neolasioptera rostrata Gagne, new species

Neolasioptera rostrata produces an enlargement of the receptacle of either male or female flowers of fl. halimifolia (Fig. 11). The gall is usually single-celled with one single larva. Two of the 227 galled flowers dissected during this work contained two larvae, each in its own cell and separated from the other by a thin wall. The full-grown larva is curled in a circle and fills the chamber. The gall in the receptacle is not apparent externally until the mature larva pushes the top of the gall into a conical shape and forms an exit hole at the apex. The hole is then covered with a silky membrane presumably produced by the larva. The larva then pupates or diapauses. Fifteen galls measured 0.69 ±0.12 mm wide by 1.06 ± 0.20 mm high (.y ± SD).

Hosts and Distribution.--MD on B halimifolia; FL on B glomeruliflora; TX on B halmifolia and B neglecta; NM on B salicina; and Dominican Republic on B myrsinites

The development of the midge is closely related to the bud and flower development of its host. In Maryland, adults emerged in August and September, 1984 from flowers collected in October of the previous year. Emergence coincided with normal flowering of B. halimifolia in Maryland. In 1987, galls were first observed in Texas on September 24, in male flower buds at two of three lo- cations (Table 1). Male flowers were probably attacked first because they developed sooner and were larger than female flowers. Pupae were present in both male and female flowers on October 14 at Port Lavaca. Empty galls, indicating previous adult emergence, were found on October 28, the only sample date when A', rostrata was present in both male and female flowers at all plots.

Of 600 senescent or blooming flowers sampled, 151 contained galls (25.2% infestation). The actual infestation rate was probably smaller because most of the senescent flowers had already dropped from the plant by that date and were uninfested. Of the 151 galls, adult midges had emerged from 37. Eight others contained pupae, nine contained small larvae, and 97 contained medium or large larvae. The presence of galls in the receptacles did not appear to affect pollen or seed production. Adult emergence in late October indicated the probability of a second generation. The small larvae present at that time were probably the progeny of the last adults of the first generation to oviposit.

On November 10, all male flowers had dropped, but some senescent female flowers remained on the shrubs. Of the 300 flowers sampled, 53 were galled (17.7% infestation) and contained medium to large quiescent larvae. Only a few empty galls or galls containing larvae were found in each of the following months through February, 1988 when sampling was discontinued.

Neolasioptera sp.

Baccharis glomeruliflora, halimifolia, neglecta

Larvae live in individual, spherical cells in the receptacles, where they pupate. Two generations occur per year. Overwintering larvae diapause until late the following summer when the hosts come into bloom.

Distr: MD, FL, TX, Dominican Republic