Phylloxera devastatrix

Distinguished from pecan leaf phylloxera (Phylloxera notabilis) by gall location: P. devastatrix forms galls on shoots and nuts, while P. notabilis galls appear only on leaves. Galls on shoots and nuts indicate P. devastatrix; leaf-only galls indicate P. notabilis. The two species require different management timing because P. devastatrix produces only one generation of galls per season, while P. notabilis may produce two to three generations.

Tiny, soft-bodied insects closely related to aphids. Adults are winged. Nymphs are minute and difficult to see without magnification. Galls induced by feeding range from 1/10 to 1 inch in diameter and form on shoots, twigs, and nuts.

Pecan orchards and native pecan groves. Found on pecan trees (Carya illinoinensis) throughout the native range of this host. Infestations move slowly from tree to tree because adults cannot fly long distances.

Throughout the native range of the pecan tree in North America, including Texas and other pecan-growing regions of the southern and central United States.

Overwintering eggs hatch in spring during bud break. Nymphs emerge and begin feeding on new growth when shoots are 1-2 inches long. Galls form and enclose developing nymphs. Winged adults emerge from cracked galls in late spring. Sexual forms mate, and females deposit overwintering eggs that remain protected within the mother's body through winter.

Feeds on phloem sap of pecan trees, obtained by inserting needle-like mouthparts into new shoot, twig, and nut tissue.

• Carya illinoinensis - primary hostpecan tree; attacks new growth on shoots, twigs, and nuts

Overwinters as eggs within the body of the sexual female, protected on tree bark. In spring, eggs hatch and stem mothers (fundatrices) move to buds and begin feeding on new growth, inducing gall formation. Galls enclose the developing insect. Stem mothers deposit eggs within galls; these hatch into apterous (wingless) and alate (winged) females. Eggs produced by these females develop into sexual males and females. After mating, females produce a single egg within their body and seek overwintering sites on bark, completing the cycle. The stem mother and apterous/alate females develop through hemimetabolous (incomplete) metamorphosis; sexual males and females develop through holometabolous (complete) metamorphosis. Only one generation of galls is produced per season.

Nymphs secrete substances during feeding that stimulate abnormal plant tissue development, forming protective galls. The insects feed and complete development entirely within these galls. Adults cannot fly long distances, limiting natural spread between trees.

Galls formed by this species serve as an alternate host for hickory shuckworm (Cydia caryana) larvae, which feed inside phylloxera galls in spring before pecan nuts are available. This relationship may facilitate shuckworm survival and population establishment.

Major economic pest of commercial pecan production. Widespread infestations reduce current-year yield and tree vitality, with carryover effects on subsequent production. Managed through cultivar selection (varieties vary in susceptibility), targeted insecticide applications timed to nymph emergence before gall formation, and spot-treatment of infested trees due to slow dispersal.

• Phylloxera notabilisAlso called pecan leaf phylloxera; distinguished by forming galls only on leaves rather than shoots and nuts, and by producing multiple generations per season
• Phylloxera caryaecaulisHickory phylloxeran; attacks hickory species (Carya) rather than pecan, forming globular galls on leaf blades and petioles

• pest
• gall-former
• agricultural
• pecan
• cecidogenic

• BugGuide
• GBIF taxonomy match
• iNaturalist taxon
• NCBI Taxonomy
• Catalogue of Life
• Insects and mites that feed on leaves - AgriLife Extension Entomology
• Managing Insect and Mite Pests of Commercial Pecans in Texas - AgriLife Extension Entomology
• Meet 'The Moth Man' at Bohart Museum's Moth Night | Bug Squad
• A Victory for the Bees | Bug Squad
• Gall darn it! Gall insects on hickory, oak, and elm, Phylloxera caryaecaulis, Andricus palustris, Colopha ulmicola — Bug of the Week
• grape phylloxera Archives - Entomology Today
• A Scanning Electron Microscope study of the pecan phylloxera, Phylloxera devastatrix, with observations on emergence