Biology, images, analysis, design...
Aphids Find them How to ID AphidBlog
"It has long been an axiom of mine that the little things are infinitely the most important" (Sherlock Holmes)

Search this site

Aphididae : Aphidinae : Macrosiphini : Carolinaia


Genus Carolinaia

Carolinaia aphids

On this page: Carolinaia rhois

Carolinaia [Macrosiphini]

Carolinaia is a genus of sometimes aposematically coloured aphids that feed on poison oak (Toxicodendron diversilobum) and related species. The antennal tubercles are weakly developed and the front of the head is convex. Apterae generally have five segments in the antennae, whereas alatae have six. The antennal terminal process is elongate, without numerous setae. The rostrum is 4-segmented with the apical segment approximately cylindrical, less than twice as long as basal width. The prothorax is with or without small marginal tubercles. Venation of the fore wing is regular. The hind wings may have a single oblique vein (subgenus Carolinaia) or two oblique veins (subgenera Glabromyzus and Juncomyzus). The siphunculi are about one-fifth the length of the body, and either swollen in the middle (subgenera Carolinaia and Glabromyzus) or more or less cylindrical (Juncomyzus). The cauda is one-fourth the length of the siphunculi and tapering.

The genus Carolinaia has 18-19 species recognised worldwide, 6-7 in Carolinaia s. str., 5 in subgenus Glabromyzus and 7 in subgenus Juncomyzus. Carolinaia s. str. and Glabromyzus are American, whereas subgenus Juncomyzus is east Asian. Most species are thought to host alternate between sumac (Rhus or Toxicodendron) and sedges (Cyperaceae), although there is incomplete knowledge of the life cycle for many species. Some species appear to be anholocyclic on Rhus, whilst others persist parthenogenetically on Cyperaceae in warmer climates.

The only diagnosis of the characteristics of genus Carolinaia appears to be that by Wilson (1911) from which the above summary of morphological features was extracted. This was subsequently modified to take into account the addition of subgenera Glabromyzus and Juncomyzus to the genus by Remaudière & Munoz Viveros (1993).


Carolinaia rhois (Sumac-grass aphid) North America

Adult apterae of Carolinaia rhois (see first picture below) on the primary host (Rhus) are reddish-brown, light orange or greenish yellow. Their antennal tubercles are weakly developed. The antennal terminal process is over twice as long as the base of antennal segment VI. Antennal segment III usually has less than 10 secondary rhinaria, with none on segment IV. The siphunculi are mainly black, apart from their bases, and are asymmetrically swollen on the inner edge. The cauda is pale, nearly parallel-sided with a slight neck and 5 hairs. The body length of adult Carolinaia rhois apterae is 1.9-2.3 mm. The apterae on secondary hosts (grasses) are somewhat smaller, light brown to greenish yellow with black siphunculi.

Both images above by permission, copyright Claude Pilon, all rights reserved.

Alatae (see second picture above) have a brown or greenish yellow abdomen with dusky dorsal markings. They have rather few secondary rhinaria (2-8) on antennal segment III. Immature Carolinaia rhois also vary in colour from reddish-brown or light orange to green.

In spring colonies of Carolinaia rhois occur on undersides of leaves of smooth sumac (Rhus glabra) and staghorn sumac (Rhus typhina). Hottes & Frison (1931) note that "this large brown aphid is often very conspicuous because of its superabundance on the undersides of the leaves of sumach". After several parthenogenetic generations on sumac, Carolinaia rhois then host alternates to the flowerheads of cereals and grasses (Poaceae) such as oats (Avena sativa), barley (Hordeum vulgare), wheat (Triticum aestivum), cocksfoot (Dactylis glomerata) and timothy grass (Phleum pratense). The sumac-grass aphid is widely distributed in North America, but has not been found elsewhere.



We have used the keys and species accounts of Wilson (1911), and Remaudière & Munoz Viveros (1993) together with information from Roger Blackman & Victor Eastop in Aphids on Worlds Plants. We fully acknowledge these authors and those listed in the reference sections as the source for the (summarized) taxonomic information we have presented. Any errors in identification or information are ours alone, and we would be very grateful for any corrections. For assistance on the terms used for aphid morphology we suggest the figure provided by Blackman & Eastop (2006).

Useful weblinks


  • Hottes, F.C. & Frison, T.H. (1931). The Plant Lice, or Aphidae, of Illinois. Illinois Natural History Survey Bulletin 19(3), 123-447. Full text

  • Remaudière, G. & Munoz Viveros, A.L. (1993). Révision du genre Carolinaia et Description de nouveaux taxa (Homoptera, Aphididae). Insecta Mundi 6 (1), 43-58. Full text

  • Wilson, H.F. (1911). Two new genera and seven new species of the Family Aphididae. The Canadian Entomologist 43, 59-65. Full text