What are root aphids? Root aphids are aphid species from the family Phylloxera defined by their habit of feeding on plant roots during part of their lifecycle.

In general, they are less 0.5mm long, and while their colour varies depending on species, environmental conditions and host plant, they are mainly white but can be yellow, green or brown often with a white waxy appearance. Root aphids show as a white fluffy film around the root with an insect inside. There also can be a white residue around the inside of the pot.
Species mainly affected are melaleuca, plums, crabapples and cotoneasters.

Because they’re small, about the size of a mite and often coloured to blend with roots and soil, root aphids can be hard to spot. Often, growers will see the white, waxy material that the aphids secrete, a chalkier type of the honeydew secreted by other aphids. Their bodies are more pear-shaped than oval as are mealybugs. They’re about the same size or slightly smaller than stem-and-leaf aphids with shorter legs and antennae. They’re commonly confused with the larger mealy bugs, because of the white substance they spread. In their winged stage, they can be confused with fungus gnats. Like other aphids, they have small cornicals or “tail pipes” at the end of their abdomen which also distinguishes them from mealybugs.

Because of their size and below-soil habitat they can go unnoticed, even through one or more grow cycles. Root aphid damage is often mistaken for other problems, especially nutrient deficiencies. Plants that appear to be suffering from magnesium or iron deficiency should be checked carefully for root aphids. Root aphids cause stunted growth, and droopy or yellow leaves resembling nutrient deficiencies. The yellowing (chlorosis) resembles a magnesium deficiency, and the yellow-brown spotting a calcium deficiency.

To treat – do a root prune and use a systemic such as Confidor (can get it online) or Rich Gro bug killer. Put solution in tub, soak root pruned tree for an hour and then don’t water the next day to keep the solution around the roots.

Root aphids are surprisingly adaptable and their lifecycle can vary tremendously. They reproduce asexually during the growing season. Eggs over-winter in soil or, in warm seasons, are attached to leaves and stems above the root line where they hatch and fall to the ground. The aphid bores into the root, creating scars that leave plants vulnerable to mildew and disease. As infestations increase, “crawlers” will move up the stem to feed. Once a plant is nearly destroyed, some root aphids will develop wings that enable them to seek new plants to attack. In the fall, winged aphids, now male and female, mate in brush and trees and produce more eggs. Ants are known to carry aphids from exhausted plants to un-colonized ones.