Phylloxera caryaemagna

pecan phylloxera

Phylloxera caryaemagna, commonly known as the pecan phylloxera, is a tiny, soft-bodied insect closely related to aphids and a significant pest of pecan trees (Carya illinoinensis). This is considered the most damaging of the two primary phylloxera species attacking pecans, as it attacks shoots and developing nuts rather than just leaves. The insect induces the formation of galls on new growth through chemical secretions that stimulate abnormal plant tissue development. Widespread can reduce current-year yield, impair tree vitality, and curtail subsequent production. Management requires precisely timed applications targeting the vulnerable nymph stage before gall formation encloses and protects the insects.

Phylloxera caryaemagna by (c) Mark Richman, some rights reserved (CC BY), uploaded by Mark Richman. Used under a CC-BY license.

Phylloxera caryaemagna by (c) Katja Schulz, some rights reserved (CC BY), uploaded by Katja Schulz. Used under a CC-BY license.

Pronunciation

How to pronounce Phylloxera caryaemagna: /fɪlˈlɒksərə ˌkæriəˈmæɡnə/

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

Identification

Distinguished from the pecan leaf phylloxera (Phylloxera notabilis, formerly P. devastatrix) by the location of galls: P. caryaemagna forms galls on shoots and nuts, while leaf phylloxera forms galls exclusively on leaf tissue. Shoot and nut galls are more damaging and indicate P. caryaemagna. Galls range 1/10 to 1 inch in diameter and crack open to release winged . spread slowly between trees due to limited capability.

Images

Appearance

are tiny, soft-bodied, winged insects with a delicate, almost translucent appearance. Nymphs are minute, pale, and lack wings. The galls induced by this range from 1/10 to 1 inch in diameter, appearing as conspicuous swellings on shoots and nut clusters. Winged adults emerge from cracked galls in late spring to early summer.

Habitat

Found exclusively in pecan orchards and natural stands of pecan trees (Carya illinoinensis). Requires new, actively growing shoot tissue for gall initiation. Native trees and improved varieties vary in susceptibility. move slowly from tree to tree due to limited ability of .

Distribution

Native to North America, distributed throughout the pecan-growing regions of the United States, particularly the southern and central states including Texas, Oklahoma, Georgia, and surrounding areas where commercial pecan production occurs.

Seasonality

hatch in spring during bud break. Nymphs feed on new growth and induce gall formation when shoots are 1-2 inches long. Winged emerge from galls in late spring to early summer. Unlike leaf phylloxera, this does not produce additional summer ; females hide in bark crevices and die, with eggs protected inside their bodies until the following spring.

Diet

Feeds on phloem sap of pecan trees (Carya illinoinensis), specifically from new shoot growth and developing nuts. Nymphs insert needle-like mouthparts into plant tissue to extract nutrients.

Host Associations

Carya illinoinensis - primary Pecan; only known

Life Cycle

Overwinters as protected inside the bodies of dead females in bark crevices. Eggs hatch in spring during bud break. Nymphs emerge and feed on new growth, secreting substances that induce gall formation. Nymphs develop to adulthood completely enclosed within galls. Galls crack open to release winged . Females do not produce additional galls; they hide in protected bark locations, deposit eggs within their bodies, and die, serving as protective vessels for eggs. No second or third occurs in this .

Behavior

Nymphs are sedentary, remaining fixed in feeding position on new growth until gall tissue envelops them. are weak fliers with limited capability, explaining the slow spread of between trees. Females exhibit maternal care posthumously by serving as protective containers for .

Ecological Role

Acts as a primary consumer in pecan , extracting plant sap and reducing tree vigor and nut production. Galls may provide microhabitat for other organisms, though this is not well documented. Serves as prey for and , though natural enemy impact appears insufficient for economic control in commercial orchards.

Human Relevance

Major economic pest of commercial pecan production. Widespread reduce yield, impair tree vitality, and reduce subsequent production. Management requires applications timed after bud break when growth is 1-2 inches long but before nymphs are enclosed in galls. Only infested trees require treatment due to slow . Native and improved pecan varieties vary in susceptibility, offering potential for in management programs.

Similar Taxa

Phylloxera notabilis (pecan leaf phylloxera)Also attacks pecans but forms galls exclusively on leaves rather than shoots and nuts; less economically damaging; produces multiple per year with second and third generation galls possible
Phylloxera caryaecaulis (hickory phylloxera)Attacks hickory (Carya) rather than pecan; forms galls on hickory leaves and petioles; distinct association

More Details

Management Timing

applications must occur after bud break when new growth is 1-2 inches long, but before nymphs induce gall formation that would enclose and protect them. This narrow window is critical for effective control.

Monitoring Recommendations

Orchard surveys should be conducted in May to identify and mark trees with galls for targeted treatment the following spring, rather than treating entire orchards.