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Calaphidinae : Panaphidini : Monellia microsetosa
 

 

Monellia microsetosa

Orange-spotted hickory aphid

On this page: Identification & Distribution Biology & Ecology Life cycle Other aphids on the same host

Identification & Distribution

All viviparae of Monellia microsetosa are alate. Alatae are yellow with summer and fall generations developing conspicuous spots of yellow-orange internal pigment on each side of the body (see pictures below). These spots are lost in alcohol-preserved or clarified slide mounts. Typically there are three pairs of spots, the first pair at the junction of pro- and mesothorax, the second on abdominal tergites I and II, and the third on tergites V & VI. The middle pair is usually largest. In summer and fall generations, there is also a brown line around the head, thorax and anterior abdominal segments, visible in the second picture below. The antennae are banded and the leading edge of the forewing is spotted with black. Antennal tubercles are poorly developed. The rostrum is short, reaching to just beyond front coxae. Each femur has a dark brown spot near its distal end. Abdominal tergites I-VI each have 3-8 fine hairs, usually none longer than 0.02 mm, and not borne on tubercles, but with small round pigmented spots at their bases (cf. Monellia caryella, Monellia hispida & Monellia medina which all have only 2 spinal hairs on tergites I-VI, 0.02 mm in length or longer, and often on low processes). Between the fine dorsal hairs there are numerous minute broad-based micro-setae. The siphunculi are smooth and poriform, each with the lateral hair of abdominal segment VI appended to its base. The cauda is knobbed, and the anal plate is bilobed.

First image above copyright Bill Keim, second image above copyright Kim Fleming,
both under Creative Commons Attribution 3.0 Licenses.

Immature Monellia microsetosa (not pictured) usually have two dorsal and two marginal dusky spots across each segment from the prothorax to abdominal tergite VI. The marginal spots are conspicuous on the mesothorax and abdominal tergites I & V.

Monellia microsetosa is found mainly on pignut hickory (Carya glabra), although it also occurs on six other species of Carya. It is monoecious holocyclic, with sexuales occurring in September to November. It is a well-distributed species over eastern North America, from Quebec to Florida, and from the Atlantic Coast to Arkansas.

 

Biology & Ecology

Life cycle

Monellia microsetosa overwinters in the egg stage on its host plant, Carya. The eggs hatch in spring to give the fundatrix. According to Bissell (1978) the orange spots are not [? initially] present in the fundatrix, but appear about a month after egg hatch coincident with development of external color. There then follow a series of parthenogenetic generations through the summer.

Sexual forms develop in autumn (September-November). It is very likely that the image below shows an ovipara of Monellia microsetosa, albeit it has not been identified as such by the taker of this photograph.

Image above copyright Charley Eismann, under a Creative Commons Attribution License.

Bissell (1978), who found sexuales of Monellia microsetosa quite frequently on Carya in October, states that live oviparae usually have two or three pairs of internal orange spots from first instar to adult ovipara, much like the viviparae. Quednau (2003) gives a drawing of the ovipara of this species which shows broken transverse sclerotized bands across the dorsum. These bands are not very evident in the specimen shown above, although some of the dark scleroites are joined to form short bars.

 

Other aphids on the same host

Monellia microsetosa has been recorded on at least 5 hickory species (Carya glabra, Carya laciniosa, Carya ovalis, Carya ovata, Carya tomentosa).

Acknowledgements

We are grateful to Bill Keim, Kim Fleming and Charley Eismann for making their images of Monellia microsetosa available for use under a creative commons licence.

We have made identifications from high resolution photos of living specimens, along with host plant identity. We have used the keys and species accounts of Richards (1965), Bissell (1978) and Quednau (2003) along 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

References

  • Bissell, T.L. (1978). Aphids on Juglandaceae in North America. Maryland Agric. Expt. Stn., 78 pp.

  • Quednau, F.W. (2003). Atlas of the Drepanosiphine Aphids of the World. Part II. Memoirs of the American Entomological Institute 72, 1-301 (p 30).

  • Richards, W.R. (1965). The Callaphidini of Canada (Homoptera: Aphididae). Memoirs of the Entomological Society of Canada 44, 1-149. Abstract