Phylloxera caryaesepta

(Shimer, 1869)

pecan leaf phylloxera, pecan phylloxera

Phylloxera caryaesepta is a tiny, soft-bodied insect in the Phylloxeridae, closely related to aphids. It is a significant pest of pecan trees (Carya illinoinensis), forming conspicuous galls on leaves, twigs, and nuts. The survives winter as in bark crevices, with nymphs emerging during spring bud break to feed on new growth. Unlike the related pecan leaf phylloxera (Phylloxera notabilis) which attacks only leaves, P. caryaesepta damages shoots and nuts, making it more economically destructive. Heavy can reduce yield, impair tree vitality, and curtail subsequent production.

Pronunciation

How to pronounce Phylloxera caryaesepta: /fɪˌlɒksˈɛrə kærˌjaɪəˈsɛptə/

These audio files are automatically generated. While they are not always 100% accurate, they are a good starting point.

Identification

Distinguished from pecan leaf phylloxera (Phylloxera notabilis) by gall location: P. caryaesepta forms galls on shoots and nuts in addition to leaves, while P. notabilis restricts galls to leaf tissue only. Galls on nuts and shoots indicate P. caryaesepta. The two often require microscopic examination for definitive separation. Both differ from other gall-forming insects on pecan by the small size of the insect and the globular, hollow structure of the galls.

Appearance

Tiny, soft-bodied insect resembling an . are winged. Nymphs are minute and enclosed within plant galls. Galls range from 1/10 to 1 inch in diameter, appearing as swollen, globular growths on leaves, petioles, twigs, and nuts. Galls are initially green and may become reddish as they mature. Winged adults emerge from galls when they crack open.

Habitat

Pecan orchards and native pecan groves. Requires pecan trees (Carya illinoinensis) as . Found on new growth where galls form. move slowly from tree to tree due to limited capability.

Distribution

Native to North America. Found in pecan-growing regions of the United States, particularly Texas and surrounding states where commercial pecan production occurs. Distribution follows the range of its plant, Carya illinoinensis.

Seasonality

hatch during spring bud break. Nymphs feed and induce gall formation on new growth. Winged emerge from galls in late spring to early summer (approximately May). Some females produce additional if new growth remains available; others overwinter. No additional gall generations are produced by the most damaging form.

Diet

Feeds on phloem sap of pecan trees (Carya illinoinensis). Nymphs insert needle-like mouthparts into leaf, shoot, or nut tissue and secrete substances that stimulate abnormal plant growth (galls), within which they continue feeding and development.

Host Associations

  • Carya illinoinensis - primary pecan; required for gall formation and development

Life Cycle

Overwinters as in bark crevices or near old galls. Eggs hatch in spring during bud break, producing nymphs that feed on new growth and induce gall formation. Nymphs complete development inside galls, which range from 1/10 to 1 inch in diameter. Galls crack open in late spring, releasing winged . Some adult females deposit eggs producing second or third if new growth is available; others hide in protected bark locations, die, and overwinter with eggs protected inside their bodies. The more destructive forms do not produce additional galls.

Behavior

Nymphs stimulate plant tissue to form protective galls through chemical secretions during feeding. Winged emerge from cracked galls and disperse short distances to new growth or sites. Cannot fly long distances; spread slowly between trees.

Ecological Role

Herbivore and gall-former on pecan. Creates structure (galls) that may be used by other organisms. Serves as prey for and in pecan agroecosystems, though natural enemy impacts on are insufficient for commercial control.

Human Relevance

Major economic pest of commercial pecan production. Damage to shoots and nuts directly reduces yield and tree vitality. Management requires applications timed after hatch but before gall formation protects nymphs—typically when new growth is 1 to 2 inches long. Treatment of individual infested trees is often sufficient due to limited . Cultivar susceptibility varies; improved varieties and native trees show differential resistance.

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