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Rose - columbine aphidOn this page: Identification & Distribution Other aphids on the same host
Identification & Distribution:
Apterae of Longicaudus trirhodus on their primary host (rose, see first picture below) are pale yellowish-green and lightly wax-dusted, with slightly darker green transverse bands across the abdomen. Apterae on the secondary hosts (columbine, see second picture below) are more yellow-green. The third antennal segment is distinctly longer than the total length of the fourth and fifth antennal segments. The siphunculi are cone-shaped with dark tips and much shorter than the cauda. The cauda is long and finger-like much longer than its basal width. The body length of Longicaudus trirhodus apterae on rose is 2.0-2.7 mm - those on secondary hosts are often smaller, down to 1.3 mm.
The images below show alate Longicaudus trirhodus, dorsal and ventral, in alcohol.
The clarified slide mounts below are of adult viviparous female Longicaudus trirhodus : wingless on the primary host, on the secondary host, and winged.
The rose - columbine aphid host alternates from rose (Rosa spp.) in winter and spring, to cultivated columbine (Aquilegia vulgaris) and meadow rue (Thalictrum) in the summer. Overwintering eggs of Longicaudus trirhodus on roses hatch in March, producing fundatrices. In April these yield small colonies on young leaves and buds. In May or June these colonies produce emigrant alatae which fly to the secondary hosts where their offspring feed on stems and leaf undersides. Autumn migrants fly to roses in October. The oviparae are unusually small, with a body length of only 1.0-1.3 mm. They have swollen dark hind tibiae bearing numerous scent glands. The males are alate and much larger, with body length of 1.8-2.1 mm, and with short broad abdominal cross-bars. Longicaudus trirhodus is found across Europe, Asia and North America.
Other aphids on same host:
Longicaudus trirhodus has been recorded from 20 Rosa species.
Blackman & Eastop list about 70 species of aphid found feeding on Rosa (rose) species worldwide, and provide formal identification keys. The genus Rosa contains perhaps a hundred species, plus hybrids thereof, and thousands of cultivated varieties of 'garden' & agricultural roses. Blackman & Eastop (1984) list thirty-or-so species of aphids that feed on cultivated 'roses', worldwide (Show World list). Of those aphid species, Baker (2015) lists 12 as occurring in Britain (Show British list).