Description and Biology
Foxglove aphid, Aulacorthum solani, is usually light green with slightly darker green spots at the base of the cornicles (long tubes that look like dual “exhaust pipes” at the rear), but it has several color forms, ranging from green to orange to pink. Winged adults are browner in color than the wingless forms, and have various black markings. Foxglove aphids also have black banding on their legs and antennae, which is not present on the other common greenhouse aphids. Foxglove aphid has a very short life cycle and populations can build rapidly. This aphid seems to thrive in cool spring conditions, fading out in summer heat. It can apparently overwinter outdoors on orange hawkweed and meadow hawkweed as well as other weeds. Males are not present under greenhouse conditions so these aphids reproduce by giving birth to live young, and their daughters are even born pregnant – they already have their own daughters developing inside them as soon as they’re born! Populations can remain active all winter in greenhouses, and they reproduce faster than other aphids at cooler temperatures.
Foxglove aphid has a wide host range from herbs to shrubs. It can transmit lettuce mosaic virus to lettuce. Foxglove aphids cause plant wilting, yellowing of leaves, and also leaves behind unsightly whitish cast skins that have been shed as they grow. Foxglove aphids also excrete large amounts of honeydew: a sticky, sugary substance that can encourage the growth of dark grayish sooty molds on plants. The saliva of foxglove aphid is toxic to some plants causing curled and twisted leaves, spots of dead leaf tissue, and can even early leaf-drop. It distorts the leaves of zonal and ivy geraniums but not astilbe. Because of this, foxglove aphid may cause irreversible cosmetic damage to ornamental plants at much lower numbers than that seen with other types of aphids.
Watch for early signs of plant damage, honeydew, cast ‘skins’ on leaves and of course the aphids themselves. Look closely as foxglove aphids are otherwise well-camouflaged. If interested in biological control in greenhouses, release the biocontrol agent after aphids are present but long before they cause noticeable damage. The parasitoid wasp Aphidius colemani, used for green peach and melon aphids, does not control foxglove aphid so use either Aphidius ervi or Aphelinus abdominalis. This aphid is susceptible to most insecticides labeled for home use on ornamental plants including insecticidal soaps and horticultural oils.
- Biology of the Foxglove Aphid in the Northeastern United States. Wave, H. E., A. S. Wayland, G. W. Simpson. 1965. USDA ARS Technical Bulletin No. 1338. 45 pp.
- Foxglove aphid and spring floral crops. Jandricic, S. and J. Sanderson. 2011. Greenhouse Canada. Greenhouse Canada is an Annex Business Media publication.
- How to Outfox Floxglove Aphids in the Greenhouse. Summerfield, A., M. La Spina, and R. Buitenhuis. 2018. Greenhouse Grower.
- Foxglove Aphid, Scientific Name: Aulacorthum solani. Natwick, E.T., W. E. Chaney and N. C. Toscano. 2009 (Update). University of California Agriculture and Natural Resources. UC IPM. Statewide Integrated Pest Management Program. How to Manage Pests, Pests in Gardens and Landscapes. UC ANR Publication 3450.
- Extension Plant Pathology Publications and Factsheets
- Horticultural Science Publications
- North Carolina Agricultural Chemicals Manual
For assistance with a specific problem, contact your local Cooperative Extension Center.
This Factsheet has not been peer reviewed.
Publication date: May 20, 2016
Revised: Sept. 17, 2019
Recommendations for the use of agricultural chemicals are included in this publication as a convenience to the reader. The use of brand names and any mention or listing of commercial products or services in this publication does not imply endorsement by NC State University or N.C. A&T State University nor discrimination against similar products or services not mentioned. Individuals who use agricultural chemicals are responsible for ensuring that the intended use complies with current regulations and conforms to the product label. Be sure to obtain current information about usage regulations and examine a current product label before applying any chemical. For assistance, contact your local N.C. Cooperative Extension county center.
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