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Utamphorophora are medium to large aphids with the antennal tubercles moderately developed, their inner side parallel or diverging with processes. The antennae are about as long as the body or longer, with inconspicuous hairs. Apterae are with or without secondary rhinaria. Their siphunculi are rather long and more or less swollen. The cauda is elongate, constricted near the middle.
There are 13 species in the world, most of them in America and East Asia. The ancestor of the group probably host alternated between Rosaceae and grasses.
Utamphorophora humboldti (American grass leaf aphid) North America, Europe
Adult apterae of Utamphorophora humboldti are apple-green with a pair of distinct dorsal darker green broad longitudinal stripes, making it appear to have a pale spinal longitudinal stripe. The antennae are darker towards their apices, and tarsi are dark. The inner sides of the antennal tubercles are converging or nearly parallel, with low conical wrinkled processes. The median frontal tubercle is very low. The siphunculi are pale, or dusky especially on the apical two thirds, and have the apical two thirds swollen. The cauda is pale. The body length is 1.9-2.6 mm.
Utamphorophora humboldti alatae have much darker pigmentation, with dark marginal sclerites on the abdomen, as well as intersegmental markings and two rows of rather large and dark paired pleural spots.
In North America the American grass-leaf aphid host alternates from ninebark (Physocarpus, Rosaceae) to the upper side of the leaf blades or flowerheads of various grasses (such as Poa, Dactylis, Festuca, Lolium). In Europe it mainly overwinters parthenogenetically on grasses. Utamphorophora humboldti is native to North America, but since 1975 has also been found in England, France and The Netherlands.
Utamphorophora crataegi (Four-spotted hawthorn aphid) North America
Adult apterae of Utamphorophora crataegi (see first picture below) are light lemon to canary-yellow, with two pairs of grass-green spots, one pair on each of abdominal segments I and IV. There are no secondary rhinaria on antennal segment III, and the hairs on antennal segment III are all less than half the basal diameter of that segment. There is no dark abdominal pigmentation. The legs are generally pale, with the tibiae light brown towards the apices, and the tarsi black at the tip. The siphunculi and cauda are the same color as the abdomen. The siphunculi are slightly to moderately swollen on the distal half and have no polygonal reticulation. The cauda is broad, tapering, rather acute and bears 3 pairs of lateral hairs, one of these pairs close to the tip. The body length of adult apterae is 1.7-2.3 mm. Immature Utamphorophora crataegi (see second picture below) closely resemble adult apterae.
Images above by permission, copyright Claude Pilon, all rights reserved.
The alate Utamphorophora crataegi (not pictured) has the head and thorax pale, the thoracic lobes brown to dark golden brown, and the abdomen lemon-yellow, marked with 4 grass-green quadrate spots as in the aptera. It has no dark abdominal pigmentation There are secondary rhinaria on antennal segments III and IV.
Utamphorophora crataegi feed on hawthorn (Crataegus species), often forming large colonies on twigs, shoots and leaves, causing curling when on leaves. There is no host alternation, and sexuales occur in September-October. Hottes & Frison (1931) describe it as "a comparatively rare species ... that feeds in small numbers upon the undersides of the leaves of Crataegus and apparently is never abundant enough to cause damage and attract attention." Palmer (1952), on the other hand, states "it is rather common, with infestations sometimes heavy and injurious". The species is widely distributed in North America.