Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hemiptera
Suborder: Sternorrhyncha
Superfamily: Aphidoidea,
Family: Aphididae
Subfamily: Aphidinae
Tribe: Macrosiphini
Genus: Cavariella
Species: Cavariella aegopodii
Binominal name: Cavariella aegopodii
Common name: Willow carrot aphid, Willow aphid, Carrot aphid

Cavariella aegopodii is an invasive aphid that is globally distributed in temperate and warm temperate regions of the world.
The wingless summer form of Cavariella aegopodii is a small and green or reddish aphid with a body length >3 mm. The tips of the antennae and the top of the legs next to the body are brown in colour. The antennae are about 0.4 times the body length. The wingless forms have a second tail-like process called the supracaudal process directly above the cauda giving the aphid the appearance of having twin tails.
The winged forms have a black head and thorax. The abdomen is pale green with dark areas on the sides and dark bands on the top. The antennae are black. The legs are pale in colour and black at the tips.

Cavariella aegopodii feeds on many species of nearly 10 plant families. It infests carrot and other species of Umbelliferae. The aphid can cause direct damage to the host and it may also transmit several types of plant virus, these include Carrot motley dwarf, Carrot red leaf, Carrot yellow leaf, Parsnip yellow fleck, Celery mosaic virus, Sugarbeet mosaic virus, and Cauliflower mosaic virus.
This species overwinters primarily as eggs on Salix species.

The reddish-brown form.
Cavariella aegopodii carrot aphid.jpg

The green form.
1-Aphid carrot aphid.jpg

Thanks to Wikipedia for text and information: