Cinara strobi

(Fitch, 1851)

White Pine Aphid

Cinara strobi, the white pine , is a large aphid specialized on white pine (Pinus strobus). It is notable for exceptionally high autumn that produce copious honeydew, attracting stinging and creating nuisance conditions. The species exhibits parthenogenetic during the growing season, with live birth of nymphs accelerating population growth. Uniquely among Cinara aphids, C. strobi harbors three bacterial endosymbionts—Buchnera aphidicola, Sodalis sp., and Serratia symbiotica—representing an intermediate stage of replacement where the latter has become metabolically incompetent yet persists.

Cinara strobi eggs by Beatriz Moisset. Used under a CC BY-SA 4.0 license.

Cinara strobi eggs closeup by Beatriz Moisset. Used under a CC BY-SA 4.0 license.

Pronunciation

How to pronounce Cinara strobi: //ˈsɪnərə ˈstroʊbaɪ//

These audio files are automatically generated. While they are not always 100% accurate, they are a good starting point.

Identification

Distinguished from other aphids by specificity on white pine, large size relative to most aphids, and extremely long rostrum. Autumn producing heavy honeydew deposits are diagnostic. Distinguished from other Cinara by association with white pine rather than other conifer hosts.

Images

Appearance

Large with an exceptionally long beak (rostrum) at the front of the adapted for tapping into phloem. Body coloration not explicitly described in sources but typical of Cinara aphids (dark, often brown or black). and nymphs found clustered on pine branches and needles.

Habitat

White pine (Pinus strobus) trees in forested and urban settings. Found on branches and needles where phloem feeding occurs.

Distribution

North America, associated with the range of its plant white pine (Pinus strobus). Documented in eastern North America including the DMV (DC-Maryland-Virginia) region.

Seasonality

Peak in autumn (September-October). Overwinters as on pine needles. Parthenogenetic during growing season transitions to producing eggs as cold weather approaches.

Diet

Phloem sap from white pine (Pinus strobus). Excess excreted as honeydew.

Host Associations

Pinus strobus - obligate White pine; sole plant for feeding and

Life Cycle

Complex with seasonal shift in reproductive mode. During growing season: parthenogenetic females give live birth to daughters (viviparity), with embryos of next carried before birth, compressing generation time. In autumn: winged sexual males and females produced, mate, and females deposit on pine needles. Eggs survive winter cold, hatch in spring.

Behavior

Forms dense on pine branches. Produces large quantities of honeydew that falls from trees, attracting yellowjackets, bald-faced hornets, European hornets, and paper wasps. Parthenogenetic allows rapid increase from few individuals to thousands.

Ecological Role

Phloem feeder that transfers nutrients from plant to via honeydew. Honeydew supports in autumn and provides substrate for growth, which blackens plant surfaces. Serves as model organism for studying bacterial endosymbiont replacement and erosion.

Human Relevance

Nuisance pest when abundant due to sticky honeydew falling on sidewalks, vehicles, and people. Attracted create safety concerns in urban areas. Not a direct agricultural pest but can reduce aesthetic value of ornamental white pines.

Similar Taxa

Other Cinara speciesOther Cinara aphids feed on different conifer (spruce, fir, cedar, larch); C. strobi distinguished by white pine specificity and exceptionally long rostrum
Longistigma caryaeGiant bark aphid also produces copious honeydew and attracts , but feeds on hardwood trees (oak, hickory) rather than conifers

More Details

Endosymbiont biology

Cinara strobi uniquely harbors three fixed bacterial endosymbionts: Buchnera aphidicola (provides ), Sodalis sp. (co-primary , contributes to nutrition), and Serratia symbiotica (highly eroded , pseudogenized, no longer contributes to nutrition). This represents an intermediate stage of symbiont replacement where a once-competent symbiont is retained despite providing no apparent benefit.

Honeydew production

Phloem sap is nitrogen-poor but -rich. To obtain sufficient nitrogen, aphids must ingest large volumes of sap, excreting excess carbohydrates as honeydew. A single colony can produce enough honeydew to create visible wet patches on pavement and vehicles beneath infested trees.