Rhopalomyia anthophila

Rhopalomyia bulbula

Rhopalomyia capitata (summer generation)

Rhopalomyia capitata (spring generation)

Rhopalomyia clarkei

Rhopalomyia cruziana

Rhopalomyia fusiformae

Rhopalomyia lobata

Rhopalomyia pedicellata

Rhopalomyia solidaginis (summer and autumn generations)

Rhopalomyia solidaginis (spring generation)

Rhopalomyia gina

Rhopalomyia hirtipes

Rhopalomyia guttata

Rhopalomyia inquisitor

Rhopalomyia thompsoni

Rhopalomyia racemicola

Rhopalomyia s-fistulosa-stem-cluster-gall

The gall ... constitutes a modified capitulum. It is cylindrical, 5–10 mm long and 2–3.5 mm wide, usually slightly wider at base than at the tip. The gall is green but densely covered by short, white hairs that give it a whitish, fuzzy appearance. Galls are almost always situated among normal capitula, and are accompanied by tiny leaves and/or ray florets at their base. Each gall contains a single smooth, thick-walled chamber. Inside this chamber is an inner, conical chamber with very thin walls, containing a single larva, facing downwards. Larvae turn to face upwards inside the gall before pupation. The gall’s wall is much thinner apically than laterally, and galls that contain pupae sometimes have slits at their tips ... Galls become apparent in mid August and pupation takes place in late August to mid September.

Galls are found in clusters of 3–15 on rhizomes, at the base of spring shoots. The gall is single-chambered, resembles a bud, with acute apex and base, 4.5–6.0 mm long and 1.5–2.5 wide. The surface of the gall is smooth and white, with green stripes where it is exposed to light.

...the much slower-developing summer-generation galls ... become apparent around mid June and vary considerably in size. These galls are composed of several wide leaves that surround dozens of densely packed, smaller and shorter leaves, giving the gall a shape of a little sunflower that appears flatter than the similar gall of R. solidaginis on S. altissima ... Occasionally, the outer leaves merge to form a continuous sheath around the central part of the gall. Summer galls reach their final size when the larvae are still tiny first instars that are found at the base of the rosette leaves. Six to twenty white, conical chambers, similar to those found in the spring galls, appear in the gall only when the larvae molt into third instars. Larvae are usually found deep at the bottom of the chamber, facing down. The chambers are 4–6 mm high and 1–2 mm wide, and are situated among the short leaves in the center of the gall rather than being individually surrounded by a group of longer leaves, as in the rosette gall of R. solidaginis.

The spring-generation galls, described here for the first time, appear in early to mid May in young S. gigantea sprouts, and are therefore found very close to the ground... The galls are composed of many short and narrow leaves among which 1–8 white, conical chambers are situated ... each containing a single orange larva. The white chambers appear in the gall only when larvae are second instars. ..The central complex of short leaves is about 3 cm in diameter and surrounded by 5–10 much longer and wider leaves, giving the gall a star-like shape and an overall diameter of up to 10 cm ... At young stages of development, the longer, surrounding leaves may sheath tightly the center of the gall and these loosen at a later stage.

The galls are small, conical and single-chambered, usually occurring on the lower side of leaves but occasionally on the upper side of leaves and on stems ... When on leaves, the gall is always attached to either a major or minor vein ... Each gall contains a single white larva. Galls on S. rugosa are 2.5–6.0 mm long and 0.7–1.2 mm wide at widest part, tapering toward apex, green to yellowish green, and covered by short, whitish hairs. Very young galls are sometimes accompanied by a tuft of hair at their base, almost as long as the gall itself.

The floret/capitulum galls of this species have not been described in detail and the host plant is unknown, hence it is impossible to determine whether this species is distinct and who its relatives among the Rhopalomyia spp. on goldenrods are. According to the information given by Felt (1915), the galls were collected in Santa Cruz Mts. in California in August 1889 and adults emerged from them “before May 1890”.

The galls of this species ... are identical to those of R. pedicellata ... except for the lack of a pedicel. This difference is consistent and no intermediate forms were found. The galls are found on leaves, stems and inflorescences, are 6–12 mm long, 1–2 mm wide at the base, and tapered towards apex. Galls are often found in aggregations ...They are smooth, green to purplish-green with longitudinal darker lines, contain a single chamber, and are smooth and shiny on the inside.

The multi-chambered galls are induced in apical and lateral buds. They are first apparent in mid May, when they form about 1 cm-wide globular swellings in shoot tips. ... Some galls occur in clusters around the shoot tip or in adjacent lateral buds... At this point, several leaves surround a small spongy mass at the base of the gall, which grows gradually over the next month up to a final size of 6 cm in diameter. ... The leaves that are tightly wrapped around the spongy mass are much wider than the normal, thin leaves of the plant ... Around the second week of June, these leaves begin to loosen, revealing the whitish tissue in which 5–35 larval chambers are embedded. Adults emerge from late June to mid July, at which point the fleshy core of the gall is exposed. ... Soon after the gall midges emerged, the fleshy tissue turns black, and dry galls remain on the plants for several weeks.

The gall is found on stems, leaves, or inflorescences. This is a delicate, slender, 14–21 mm long gall, carried on a pedicel that is about half as long as the remainder of the gall (hence the species’ name). ... The gall is single-chambered, green to purplish-red, with longitudinal ridges, and tapered at both ends. The internal walls of the gall are smooth and shiny and the larva is usually found facing downwards at the bottom of the chamber. Galls are common and found from mid June to September. ... The structure of the gall is identical to that of R. fusiformae except for the presence of the pedicel.

This species is bivoltine and induces morphologically different bud galls in spring (April–May) and summer (August–September), which are very similar on all three host plants. ... White chambers that are similar to those in the spring galls appear in the gall around mid July ... and each chamber contains a single larva that is found deep in the chamber, facing downwards. Each chamber is surrounded by a group of very short and narrow leaves, which in turn are surrounded by longer and wider leaves to form a distinct subunit within the gall. Usually at least 2–5 subunits are clumped together at the shoot apex to form a conspicuous rosette that is 3–5 cm in diameter. ... The rosette gall of *R. capitata* ... is superficially similar but does not contain distinct subunits and appears flatter than galls of *R. solidaginis*.

This species is bivoltine and induces morphologically different bud galls in spring (April–May) and summer (August–September), which are very similar on all three host plants. The spring generation galls ... are inconspicuous and difficult to locate due to the minor difference between galled and normal shoots, although the growth of galled ramets is sometimes stunted and they therefore appear shorter than ungalled ramets. ... The apical leaves of a galled ramet appear splayed, and the base of the gall from which they originate is slightly thickened. Each gall usually contains only one conical, white chamber in the middle of the apical meristem (Fig. 76), ca. 3 mm long, and containing a single larva that is usually found deep at the bottom of the chamber with its head facing downwards. Occasionally 2–3 chambers are found in the same gall and may be attached to each other longitudinally. The chamber is surrounded by approximately 10 leaves that are much shorter and thinner than normal leaves. ... On S. altissima, these modified leaves are lighter in color, especially along their mid vein. These are surrounded in turn by a whorl of leaves of normal shape and size. Galls contained pupae already in early May, suggesting rapid development of the spring generation soon after the plants sprout.

Galls of this species ... are similar in appearance to galls of R. clarkei on S. rugosa ... and of its close relative on S. gigantea. ... They are 2.8–5.0 mm long and 0.6–1.3 mm wide at widest part (n=22), smooth and green, often with purplish longitudinal lines and tip, and are most often found on the upper side of leaves. The position of the gall is usually apparent on the other side of the leaf only as a small scar, but some galls had a long, curly appendage extending from that side. ... Galls were found in mid May to mid June and adult emergence began in early June ... Further examination of the plants in early August failed to reveal any galls, but Gagné (1989 and pers. com.) found similar galls in late September on leaves subtending and composing the rosette galls of Asphondylia monacha on S. juncea in Silver Spring, MD. It therefore appears that this species completes at least two generations per year. 

Galls of this species appear at the base of the stem in mid June to mid July ... They mostly occur just above the ground but are occasionally found up to 60 cm above it ... and are surrounded by a rosette of long leaves. It is therefore clear that the gall develops from vegetative buds rather than from rhizomes. The young gall is wide at base and has a tapered tip ... which disappears as the gall matures. During July and August, the gall becomes ovoid, 8–25 mm long and 6–36 mm wide and often changes its color from green to brownish, resembling a small potato.... Galls are spongy and usually multi-chambered, containing 1–30 individual larvae in separate chambers ... As long as the larvae feed, they face downwards inside their chambers, but before the onset of pupation, in early August, they turn to face upwards. Shortly before adult emergence, the gall splits open at its apex into several lobes, similar to the shell of a hickory nut ... Adults emerge from early to late September, after which the gall shrivels and dries on the stem. Emergence of all adults from the same gall may continue over more than a week. Some galls fail to split, resulting in death of the pupae inside the gall. Galls of this species can be very difficult to locate and were rare even in fields where S. juncea was the dominant plant.

The galls were found by R.J. Gagné in capitula, carried on a pedicel among normal capitula but shorter and hidden by them. The gall is conical-cylindrical, smooth, white to green, or sometimes red, and apically tapering. Each gall contains a single larva. A galled capitulum is wider and harder to the touch than capitula without galls.

Felt (1908) described this species from a single male and a single female and speculated (Felt 1915) that it develops as an inquiline in galls of R. capitata. However, we did not find any signs of its presence in galls of R. capitata. Given the morphological similarity of R. inquisitor adults to those of R. clarkei, it is possible that R. inquisitor is not an inquiline but, rather, induces inconspicuous conical galls that escaped Felt’s attention. In the present study we found such galls on leaves of S. gigantea ... including on modified leaves composing the bud galls of Dasineura folliculi. This finding supports our hypothesis that R. inquisitor may well be the species responsible for these galls, but the galls were rare and we were unable to rear adults from them ... A comparison of such adults with the type specimens of R. inquisitor would be the only way to determine whether the galls we found are indeed those of R. inquisitor. ...
Galls of this species [given as Rhopalomyia sp. ] are very similar in shape and size to galls of R. clarkei on S. rugosa, but are much rarer and are smooth rather than hairy. They are 2–3.3 mm long and 0.5–0.7 wide at widest part, green, sometimes with dark longitudinal lines, and most were found on the upper side of leaves. Due to the scarcity of the galls and to high parasitism rates we were unable to rear adults from them, but a molecular analysis based on larvae indicated that this species differs from R. clarkei (Dorchin et al., in prep.). Some galls were found on leaves composing the bud galls of Dasineura folliculi on S. gigantea and there is no reason to believe they do not occur also on modified leaves of the rosette gall induced by R. capitata on the same host plant. If this is indeed the case, then these galls may actually be those of R. inquisitor, which was reported by Felt (1908) as an inquiline in R. capitata galls (see details under R. inquisitor).

This species has two generations per year, both of which develop in rhizome galls. The spring generation galls are solitary or clustered, bulbous, fleshy masses with 1–8 chambers each. As the galls develop, they become apparent above the ground and burst open before adult emergence in early May ... The second generation galls constitute brownish, globular, and usually multi-chambered swellings of the rhizomes, which were still completely subterranean in mid August, when they contained mature larvae. Pupation took place in late August to early September, at which time the galls became elongate and fleshier. Shortly before adult emergence the galls became apparent above the soil surface, and adults emerged from mid to late September. 

The green, bristly, onion-shaped capitulum galls are situated among normal capitula and can sometimes be found in aggregations. They were recorded by Felt (1907a, 1915) from *S. altissima* in North Carolina, and Gagné (1989) reported similar galls on *S. fistulosa* from Florida, which he attributed tentatively to the same species. The description of the galls and the mention of previous records of this species in Felt (1915) actually refer to the galls of *Schizomyia racemicola* rather than those of *R. racemicola* (see Gagné 1971). The true nature of [Felt's 1907] *R. racemicola* galls is therefore uncertain, and we tentatively adopt Gagné’s assumption that the galls he received from Florida are those of *R. racemicola*. Adults emerged in mid September in North Carolina, and in December in Florida. Given that the galls develop in capitula, we assume that *R. racemicola* is univoltine, but verifying the identity of the host plant and the galls, and clarifying the life history of this species require more investigation.

The galls of this species were found by E. Fontes in May and June of 1982 around Gainesville, Florida (Fontes et al. 1994). They developed on young stems, and seemed to have stunted the growth of the apical meristem, because galled ramets were usually only 30 cm tall and atypically branched under the galls. The galls are oval with a tapered tip, single-chambered, grayish, and are typically aggregated around a stem to form a “star-like” structure. Galls found in August were already dry except for one or two records.

Revision of the goldenrod-galling Rhopalomyia species (Diptera: Cecidomyiidae) in North America