Life cycle and appearance of the Cannabis aphid

Adult cannabis aphids are between 1.8–2.7 mm long. They are normally wingless but a winged form appears in late summer. Early in the season, the aphids are nearly colourless to pale yellow, and as the days become shorter, they change to light green or brown with dark green stripes running the length of the body. The winged forms have a dark head and thorax. Cannabis aphids have long antennae (1.1–2.2 mm) and between these are two short knobs (antennal tubercles). Their cornicles (the pair of small, upright, backward-pointing tubes on the aphid's rear end) are white and almost ⅓ the insect’s body length.

Phorodon cannabis usually reproduce asexually; females are essentially born pregnant and give birth to live, genetically identical offspring. Newborn nymphs will typically reach maturity within a couple of weeks, and adults live up to a month.

Outdoors, as the days shorten in late summer/early autumn, winged males and sexually-reproducing females are produced. After mating, the female lays her eggs on leaves, flowers and stems to overwinter and produce the next generation of aphids in the spring. In greenhouses, sexual reproduction is very rare and only triggered if lighting signals a shortening day.