Small, soft, pear-shaped insects clustered on a plant, with twisted and curled leaves, are aphids. They feed on the sap; heavy feeding yellows and stunts the plant.
Promising · ignored, it still works, just worse · the planner suggests it
How it works
Aphids feed on plant sap, injecting saliva into the host as they feed. Severe feeding twists and curls the leaves, yellows the foliage, stunts or kills shoots and slows growth. They secrete a sticky, sugary honeydew that can let sooty mold grow on the leaves, though the honeydew itself does not harm the plant.
What to do about it
Knock them off with a strong spray of water from the hose, which also washes off honeydew. Protect the lady beetles, lacewings, hover fly larvae and parasitic wasps that eat them: avoid broad pesticides, and plant flowers that bloom at different times through the season. Insecticidal soap or horticultural oil can control aphids where needed.
How much it matters: No damage threshold is invented. The source ties the harm to SEVERE feeding (twisted leaves, yellowing, stunted shoots); a few aphids on a vigorous plant often need nothing, which is why the first remedy is a hose and the natural enemies. The rule advises and never blocks.
The evidence
Evidence: confirmed against 1 source in the research-based literature.
the source
UMN Extension, 'Aphids in home yards and gardens', extension.umn.edu/yard-and-garden-insects/aphids (fetched in-container 2026-09-25, read 2026-09-25): 'Aphids are small, 1/16- to 1/8-inch-long (2-4 mm), pear-shaped, soft-bodied insects.'; 'Signs of severe aphid feeding are twisted and curled leaves, yellowed leaves, stunted or dead shoots and poor plant growth.'; 'When aphids feed, they inject saliva into their host plant to help digest the sap.'; 'Honeydew generally does not cause any harm, but can cause leaves to stick together and can encourage the growth of sooty mold.'; 'You can physically knock aphids off plants with a strong spray of water from a garden hose.'; 'Protect natural enemies by avoiding pesticide applications or using low risk products.'; 'Insecticidal soap, horticultural oil and pyrethrins can be effective at controlling aphids.'; 'There are many natural enemies of aphids that are commonly found in gardens, including lady beetles , lacewings , syrphid fly larvae and parasitic wasps.'; 'Encourage natural enemies by planting flowering plants that blossom at different times of the growing season.'
Where this rule stops
A STANDING ADVISORY on any crop (no applies_to), answering the "small insects clustered on the plant" sign in the Something's-wrong picker (symptoms.ts). It gates nothing. Insecticidal soap and horticultural oil are named because the source names them as effective; pyrethrins, which the source also lists, are left out of the remedy as a broad-spectrum product that kills the natural enemies the remedy asks the gardener to protect.
Change history
Every change to this rule is one commit. This is what the project's version history records — the date and the reason — not a summary of it.
- corpus(another rule here): new rule, Promising, verified - aphids, on any crop
Cite this page
Milpa Gardens. "Small, soft, pear-shaped insects clustered on a plant, with twisted and curled leaves, are aphids. They feed on the sap; heavy feeding yellows and stunts the plant." Evidence grade: Promising. https://milpa.garden/rules/small-soft-pear-shaped-insects-clustered-plant/
A garden-planning corpus: every claim states its evidence grade and links its sources on the page. Cite it with the grade, and add the date you read it.