Plant Symptom Chart

Pest · 4 symptoms · 3 Extension services

Aphids: what the symptom points to

Start with what you're noticing on the plant, then see how Clemson, Colorado State, and Wisconsin Extension describe that symptom to find which kind of aphid trouble matches best.

Compared here: Clemson Cooperative Extension, Colorado State University Extension, University of Wisconsin–Madison Extension. Last checked 2026-09-27.

01Curled or distorted leaves

Possible cause	Clemson	Colorado State	Wisconsin
Aphid colonies	Clemson Cooperative Extension says feeding by some aphid species injects toxins that can leave the plant tissue distorted and deformed. Source: Integrated Pest Management (I.P.M.) for Aphids · checked 2026-09-27	Colorado State University Extension says some aphids cause the leaves to curl when they infest the emerging new growth. Source: Aphids on Shade Trees and Ornamentals · checked 2026-09-27	University of Wisconsin–Madison Extension says reduced vigor, stunting, and deformed plant parts are common symptoms of an aphid infestation. Source: Aphids · checked 2026-09-27

02Sticky leaves or black film

Possible cause	Clemson	Colorado State	Wisconsin
Aphid colonies	Clemson Cooperative Extension says one sign that aphids are present is honeydew, the sticky substance they excrete, on the plant's surfaces. Source: Integrated Pest Management (I.P.M.) for Aphids · checked 2026-09-27 Clemson Cooperative Extension says honeydew looks like a sugary drink was poured on the leaves and left to dry, leaving a sticky look and feel. Source: Integrated Pest Management (I.P.M.) for Aphids · checked 2026-09-27	No matching line in the Colorado State pages we checked.	No matching line in the Wisconsin pages we checked.
Honeydew and sooty mold	No matching line in the Clemson pages we checked.	Colorado State University Extension says honeydew is the sugary waste that aphids and some other sap-sucking insects excrete. Source: Aphids on Shade Trees and Ornamentals · checked 2026-09-27 Colorado State University Extension says a grayish sooty mold grows on the honeydew, making the plant look worse. Source: Aphids on Shade Trees and Ornamentals · checked 2026-09-27	University of Wisconsin–Madison Extension says as they feed on plant sap, aphids excrete a sugary substance called honeydew, which attracts ants and lets sooty mold fungus grow on it. Source: Aphids · checked 2026-09-27 University of Wisconsin–Madison Extension says sometimes honeydew or sooty mold is the first sign that points to an aphid outbreak. Source: Aphids · checked 2026-09-27

03Insects you can see

Possible cause	Clemson	Colorado State	Wisconsin
Aphid colonies	Clemson Cooperative Extension says aphids are usually found on young, tender growth and on the undersides of leaves. Source: Integrated Pest Management (I.P.M.) for Aphids · checked 2026-09-27	Colorado State University Extension says aphids are small insects found on leaves, stems, and sometimes branches. Source: Aphids on Shade Trees and Ornamentals · checked 2026-09-27 Colorado State University Extension says aphid color varies a lot by species, ranging from very pale yellow to dark, almost black. Source: Aphids on Shade Trees and Ornamentals · checked 2026-09-27 Colorado State University Extension says all aphids are small, from about 1.5 to 5 mm long, with the bigger species found on stems and branches. Source: Aphids on Shade Trees and Ornamentals · checked 2026-09-27	University of Wisconsin–Madison Extension says aphids are soft-bodied, sap-sucking insects that are sometimes called plant lice. Source: Aphids · checked 2026-09-27 University of Wisconsin–Madison Extension says aphids are soft-bodied and pear-shaped, with a pair of tailpipe-like structures, called cornicles, sticking out from the rear of the abdomen. Source: Aphids · checked 2026-09-27
Green peach aphid	Clemson Cooperative Extension says the green peach aphid is the most common aphid species found feeding on many kinds of plants in the garden and landscape. Source: Integrated Pest Management (I.P.M.) for Aphids · checked 2026-09-27	No matching line in the Colorado State pages we checked.	No matching line in the Wisconsin pages we checked.

04Wilting or dying back

Possible cause	Colorado State
Aphid colonies	Colorado State University Extension says when aphid numbers stay very high for a long time, their feeding can cause wilting and sometimes even the dieback of shoots and buds. Source: Aphids on Shade Trees and Ornamentals · checked 2026-09-27

What to do about it. This site only covers how to recognize a problem. For what to do next, open the Extension page linked in the row: their advice is written for their region and is kept up to date by them.

Pages compared on this chart

Integrated Pest Management (I.P.M.) for Aphids, Clemson Cooperative Extension (checked 2026-09-27)
Aphids on Shade Trees and Ornamentals, Colorado State University Extension (checked 2026-09-27)
Aphids, University of Wisconsin–Madison Extension (checked 2026-09-27)