Dealing with Aphids in a Hydroponic System

What Aphids Do

Aphids are small sap-sucking insects that cluster on new growth and undersides of leaves. They pierce plant tissue to feed on phloem, causing yellowing, curling, stunting, and wilting, and excrete sticky honeydew that fosters sooty mold and can transmit plant viruses. [1]

Latin Name

Aphidoidea (family Aphididae) [1]

Identification

Soft-bodied, pear-shaped insects, 1-4 mm long
Varied colors: green, yellow, white, brown, red, black [2]
Cluster in colonies on stems and leaf undersides
Produce sticky honeydew and may be tended by ants

Alternative Names

Plant lice
Greenfly (UK)
Blackfly

Varieties (Common Species)

Green peach aphid (Myzus persicae)
Melon aphid (Aphis gossypii)
Black bean aphid (Aphis fabae)
Foxglove aphid (Aulacorthum solani)
Potato aphid (Macrosiphum euphorbiae)

Climates Where They Thrive

Temperate to warm conditions (15-25 °C), moderate to high humidity [1]
Decline under prolonged heat above 30 °C or very low humidity (< 40 % RH) [4]

Companion Planting as Deterrents

Cultivar	Hydroponic Methods	Effectiveness
Marigold (Tagetes spp.)	All (DWC, NFT, Ebb & Flow, Drip)	Moderate-releases deterrent thiophenes [5]
Chives (Allium schoenoprasum)	All methods	High-garlic-like volatiles repel [5]
Basil (Ocimum basilicum)	NFT, DWC, Drip	Moderate-aromatic oils mask host cues [3]
Mint (Mentha spp.)	Wick, Kratky, Drip	Moderate-strong scent disrupts landing [3]
Cilantro (Coriandrum sativum)	All methods	Low-attracts beneficial hoverflies & parasitic wasps [4]

Natural Predators

Ladybird beetles (Coccinellidae) [1]
Hoverfly larvae (Syrphidae) [1]
Parasitic wasps (Aphidius spp.) [1]
Green lacewing larvae ("aphid lions") [1]
Aphid midge larvae (Aphidoletes aphidimyza) [1]
Spiders and predatory mites [1]

Remedies

Treatment	Hold Period	Natural?	Effectiveness
Insecticidal soap spray	1 day	Yes	High-kills on contact [5]
Neem oil emulsion	3 days	Yes	Moderate-repellent & growth disruptor [3]
Pyrethrin spray	7 days	No	High-rapid knockdown [2]
Alcohol + water dip (70 % IPA)	2 days	No	Moderate-dislodges & dehydrates [2]

Other Remedies

Reflective mulch: Use aluminum film to confuse and repel adults [5]
Yellow sticky cards: Monitor and reduce flying adults [4]
Water-mist shock: High-pressure mist to knock off nymphs
Essential oil diffusion: Disperse lavender or peppermint vapor
Vacuum suction: Gently remove adults with a handheld vacuum

Tips and Tricks

Inspect new transplants under bright light before introduction
Maintain humidity at 50-60 % and good airflow to discourage colonies [4]
Prune heavily infested leaves and dunk off-site in soapy water
Rotate treatments weekly to prevent resistance
Clean and sanitize reservoirs and trays between crop cycles

Common Hosts

Leafy greens (lettuce, Spinach, Basil)
Tomatoes, Peppers, Cucumbers
Herbs (basil, mint, cilantro)
Strawberries, Ornamentals

Citations

[1] Aphid - Wikipedia - https://en.wikipedia.org/wiki/Aphid
[2] How to Identify and Control Aphids - The Spruce - https://www.thespruce.com/how-to-get-rid-of-aphids-2539837
[3] How to Rid Aphids From Your Indoor Hydroponic Garden - Nosoilsolutions - https://nosoilsolutions.com/how-to-rid-aphids-indoor-hydroponic-garden/
[4] How Can Hydroponic Systems Be Protected From Aphids? - Redinational - https://redinational.com/how-can-hydroponic-systems-be-protected-from-aphids/
[5] How to Get Rid of Hydroponic Pests - Eden Green Technology - https://www.edengreen.com/blog-collection/types-of-hydroponics-pests