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Macrosiphum impatientisGreen jewelweed aphidOn this page: Identification & Distribution Other aphids on the same host Damage & ControlIdentification & DistributionAdult apterae of Macrosiphum impatientis are shining green to dark green with strikingly black siphunculi. The antennae are mostly light brown, but antennal segment III is dark brown around the secondary rhinaria, as are the apices of segments III-V (cf. Macrosiphum pallidum, which has antennal segment III black except at the base). The tibiae of Macrosiphum impatientis are mainly light brown although somewhat darker towards the apices (cf. Macrosiphum pallidum, which has black tibiae). Abdominal tergites VII & VIII are usually without spinal tubercles (cf. Macrosiphum pallidum, which has abdominal tergites VII & VIII each with a pair of spinal tubercles). The siphunculi of Macrosiphum impatientis are mostly black, but with their extreme base paler (cf. Macrosiphum euphorbiae, which has the siphunculi either pale or only dusky at the apices, and cf. Macrosiphum rosae on rose, which has the siphunculi entirely black). The siphunculi taper very gradually from base to apex with 4-8 rows of rather large polygonal reticulations. If our images are representative, the cauda of the adult is conspicuously yellow. The body length of adult Macrosiphum impatientis apterae is 1.7-3.8 mm.
Both images above by permission, copyright Claude Pilon, all rights reserved. Alatae of Macrosiphum impatientis (see first picture below of IV instar alatoid & second picture of adult alate) are dark green with the thorax tinged with brown, and have dark brown to black siphunculi and antennae. The wing veins are dusky with brown bordering only the base of the radial sector. The marginal sclerites on abdominal segments II-V are sometimes dusky to light brown.
First image above by permission, copyright Claude Pilon, all rights reserved Macrosiphum impatientis host alternates from roses (Rosa spp., its primary hosts) to jewelweeds or touch-me-nots (Impatiens spp., its secondary hosts). The population overwinters in the egg stage. Sexual forms develop on rose in autumn - but since oviparae have been found on Impatiens, it seems Macrosiphum impatientis may also sometimes overwinter on its secondary host. The known distribution of Macrosiphum impatientis extends from Canada to the north-east (Pennsylvania and Virginia) and midwest (Illinois and Nebraska) of the United States. It has been considered to be a rare species in the United States, but Jensen (1998) suggests that situation may be changing. He found Macrosiphum impatientis to be common on orange jewelweed (Impatiens capensis) in the summer of 1996 in Maryland, and in spring the following year on both Carolina rose (Rosa carolina) and the increasingly widespread invasive multiflora rose (Rosa multiflora) growing near Impatiens plants. Other aphids on the same hostPrimary hostsMacrosiphum impatientis has been recorded on 2 species of Rosa (Rosa carolina, Rosa multiflora)
Secondary hostsMacrosiphum impatientis has been recorded on 2 or 3 Impatiens species (Impatiens capensis, Impatiens pallida, and possibly Impatiens ecalcarata).
Damage and controlJensen (1998) notes that further work should be done to determine the pest potential of this aphid on cultivated roses. Since Macrosiphum impatientis can feed on the exotic Rosa multiflora, it is quite likely that it could also feed on other species of exotic cultivated roses.
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