Identification & Distribution:
The adult apterae of Myzus ornatus are somewhat dorso-ventrally flattened. The dorsum is sclerotic and granulate, dirty yellowish to yellowish green, and is marked with conspicuous dark green or brownish transverse intersegmental sclerites (see first picture below). The antennal tubercles are well developed, with just a suggestion of a median frontal tubercle. The antennae are 0.5-0.6 times the body length. The siphunculi are cylindrical, slightly curved outwards, constricted below the flange and 2.1-2.7 times the length of the triangular cauda. Myzus ornatus is a very small aphid with a body length of only 1.0-1.7 mm.
Myzus ornatus is often found in mixed colonies with other species. The second picture above shows an apterous adult Myzus ornatus in the midst of a group of young Macrosiphum rosae. The two pictures below are micrographs of an apterous adult Myzus ornatus in alcohol - note the prominent antennal tubercles and the small triangular cauda largely hidden in dorsal view.
The alate viviparous female (pictured below right) has a large dark dorsal patch, not touching the marginal sclerites, with some spots and cross bands on other tergites.
The clarified slide mounts below are of adult viviparous female Myzus ornatus : wingless, and winged.
Micrographs of clarified mounts by permission of Roger Blackman, copyright AWP all rights reserved.
The ornate aphid does not host alternate and is extremely polyphagous. It often occurs in mixed-species colonies, where it can be difficult to spot amongst other aphids. It is an important pest on crucifers, cucurbits and onions and also attacks peas, soybean, strawberry and many garden ornamentals, especially in glasshouses. It also feeds on some trees such as Catalpa and Prunus, often feeding away from the main veins. Sexual forms are extremely rare and nearly all reproduction is parthenogenetic.
Not so long ago Myzus ornatus was a rare aphid. It was first discovered in England in 1932, but within a few years spread throughout the world - definitely one of Britain's more successful exports!
We especially thank King John's Nursery, East Sussex, for their kind assistance, and permission to sample.
Our particular thanks to Roger Blackman for images of his clarified slide mounts.
We have made provisional identifications from high resolution photos of living specimens, along with host plant identity. In the great majority of cases, identifications have been confirmed by microscopic examination of preserved specimens. We have used the keys and species accounts of Blackman & Eastop (1994) and Blackman & Eastop (2006) supplemented with Blackman (1974) , Stroyan (1977) , Stroyan (1984) , Blackman & Eastop (1984) , Heie (1980-1995) , Dixon & Thieme (2007) and Blackman (2010) . We fully acknowledge these authors 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).
Alan Outen, 4 June 2014
Your winter blog about finding possible Dysaphis gallica on Cymbalia muralis has prompted me to make regular checks on a wall around the corner which has a fair amount of this plant on it. I found a very few very tiny brownish aphids,
Image(s) copyright Alan Outen, all rights reserved.
one again perhaps attacked by Entomophthora,
together with a single leaf harbouring minute green nymphs.
I was really pushed to the limits of my equipment to get the images of these and those that I have which may not be good enough for any realistic identification though I note the potential options known on this host are few. I can check again and try for more and or retain specimens if you think these will be worth looking at.
Aphid on Cymbalia muralis looks like Myzus ornatus - agreed, they are not easy to photograph.
I have been 'playing' with the Entomophthorales on various things! I was disappointed by the one on Cymbalaria but will look at it again at other times just in case.