Petiole gall aphids(Pemphigus spyrothecae)Latin Name: Pemphigus spyrothecae
Common Name: poplar spiral gall aphid
Appearance:
Adult petiole gall aphids are about 1/13 inch (2 mm) long, pale green with a black thorax, and coated in wax.
They have small, thread-like antennae and don’t have the terminal abdominal tubules known as cornicles that another aphid has.
Aphids are tiny, soft-bodied insects that induce galling of the leaf stem (petiole).
Hosts plants:
It forms circular galls on the petioles of cottonwood, poplar, and aspen trees; the harm is mostly cosmetic.
Territory:
Pemphigus spyrothecae is found across Europe, North Africa (Tunisia), western Siberia, Pakistan, and Canada.
Damages caused by Petiole gall aphids:
These aphids may induce some leaf drops and are responsible for producing the intriguing galls, but they do not harm the plants in any way. The leaves are not damaged; however, they may be bent at an angle to the petiole. Aphids emerge from galls in the middle of summer and fly to a summer host, where they feed on roots until the end of the season. Aphids inflict minimal damage to poplars but can be a major issue on other plants such as lettuce.
Life History and Habits:
Pemphigus spyrothecae, often known as the poplar spiral gall aphid, is a social insect that appears altruistic. The aphids build galls and protect the colony, sometimes at the cost of their own lives. Petiole gall aphids have a one-year life cycle in which they switch between two hosts. In the fall, eggs are placed in bark cracks on Populus spp. Trees and the nymphs hatch into asexually reproducing females. Nymphs use tubular, sucking mouthparts to feed on growing leaf petioles. Feeding causes the host plant to generate gall, a swelling growth that envelops the aphid as it develops. Winged adults are created towards the end of the summer and fly back to their winter hosts.
