Hickory Leafstem Gall Phylloxera – Phylloxera caryaecaulis

Hickory Leafstem Gall Phylloxera (Phylloxera caryaecaulis)

Latin Name: (Phylloxera caryaecaulis)

Common Name: Hickory Leafstem Gall Phylloxera


  • The Hickory Leaf Stem Gall Aphid (HLSG) produces galls, or swellings, on petioles and, on special times, new hickory shoots, causing tree damage.
  • In the spring and early summer, the galls are green, leathery, and bullet-shaped, varying in size from a pea to 1/2 inch or more in diameter.
  • The aphid is a small aphid with light to greenish coloration.

Hosts plants:  In this Phylloxera species, there is no host variation.

Territory: It’s found throughout the eastern United States and Canada.

Damage caused by Hickory Leafstem Gall: 

The Hickory Leaf Stem Gall Aphid (HLSG) causes galls, or swellings, on petioles and, on rare occasions, new hickory shoots, causing tree damage. The galls are green, leathery, and bullet-shaped in the spring and early summer, with a diameter ranging from a pea to 1/2 inch or more. Galls come in a variety of shapes, including round and irregular. When the leaves fall off the tree too early in the summer, the owner feels anxious.

Description about Beneficial garden insects:

Most insects are not pests. Only those who eat attractive plants or spread illness are a nuisance to gardeners. Predators, pollinators, and parasitoids are the three sorts of useful insects. Lady beetles, praying mantids, green and brown lacewings, ground beetles, damsel bugs, syrphid fly larvae, and snakeflies are predatory insects. Predators such as spiders, predaceous spider mites, and centipedes are vital in garden ecology.

Several bee and fly species are pollinators of insects. Honeybees, bumblebees, orchard mason bees, and syrphid flies are the essential pollinators in home gardens, but many other pollinators also play a role. Small, stingless wasps or flies that deposit their eggs in or on certain host insects are parasitoids. Although these insects are difficult to observe, research has shown that they significantly influence pest bug populations.

Life History and Habits:

In the early spring, eggs hatch when fresh buds develop and bloom. Young aphids crawl to freshly developing leaves, penetrating the epidermis and draining cell sap to feed on the new growth. The aphids are encased in galls that form due to the feeding. Many generations of aphids grow within the galls during May, June, and July. In late July, the galls crack apart, turning black and jagged in appearance, and the aphids emerge. Most of the afflicted leaves begin to fall prematurely at this time. Each year, there are multiple generations of aphids. In late summer or fall, eggs are placed in cracks and fissures in the bark, as well as in ancient stem galls. Aphids lay their eggs in the gall and bark fissures during the winter.