Aphids on Alocasia: how to identify and treat

How to identify aphids on Alocasia

Small (1/16 to 1/8 inch long, per UMN Extension), pear-shaped and soft-bodied; UC IPM notes they may be green, yellow, brown, red, or black depending on the species. Often found in dense clusters on new growth, flower buds, and leaf undersides.

Damage signs to look for

Distorted or curled new growth, sticky honeydew on lower leaves and surfaces, sooty mold growing on the honeydew, yellowing on infested tissue.

Treatment ladder

1. 1Rinse the plant with a strong stream of water to dislodge most of the colony.
2. 2Spray remaining aphids with insecticidal soap. Soaps and oils kill only the aphids present on the day they are sprayed, so UC IPM notes applications may need to be repeated.
3. 3For heavy infestations, neem oil or horticultural oil also works — spray all surfaces, including new growth, and follow the label.
4. 4Severe cases on tough-leaved plants can be wiped down with a soft cloth dipped in alcohol-water solution.

Prevention going forward

• Check new growth often — UC IPM advises checking for aphids at least twice a week when plants are growing rapidly.
• Avoid heavy nitrogen fertilizer — high nitrogen favors aphid reproduction.
• Isolate new plants for one to two weeks so any pest problems become visible, as UMN Extension advises.

Life cycle

Most aphids reproduce asexually for most or all of the year, with females giving birth to live young without mating. Each adult can produce up to 80 offspring in about a week, and nymphs can mature in seven to eight days, so populations can increase with great speed (per UC IPM).

Source

Identification, treatment, and prevention guidance per UC IPM — Aphids, with other figures from UMN Extension — Insects on Indoor Plants as named in the text. Always follow the product label when applying any pesticide or horticultural oil.