common name: giant bark aphid
scientific name: Longistigma caryae (Harris) (Insecta: Hemiptera: Aphididae)
This bark-feeding aphid was first described by Harris (1841) as Aphis caryae from pignut
hickory, Carya glabra (= porcina) (Mill.) Sweet, in Massachusetts. It is the largest aphid
that occurs in the United States, and it was probably this species that was reported by Thomas
(1879) from limbs of pignut hickory in Illinois. Weed (1891) described its various forms and
gave a short note on its biology. Wilson (1909) described the genus Longistigma for this
species because of the extremely long slender stigma which extends around the end of the
wing.
nymph
L. caryae has been reported from Alabama, Arkansas, Arizona, California, Connecticut,
Delaware, District of Columbia, Florida, Georgia, Illinois, Indiana, Iowa, Kansas, Kentucky,
Louisiana, Maryland, Massachusetts, Michigan, Minnesota, Mississippi, Missouri, Nebraska,
New Jersey, New Mexico, New York, North Carolina, Ohio, Pennsylvania, South Carolina,
Tennessee, Texas, Utah, Virginia, and Wisconsin.
Apterous (wingless) viviparous female: body 6 mm long, abdomen 3.5 mm in diameter,
antennae 3 mm long, posterior legs 9 mm long. Light to dark brown except cornicles and a
few small spots on the abdomen; tips of femora, tibia and tarsi black. Cornicles very short
and truncate. Rostrum extending to posterior coxae. Body, legs and antennae with long, light
brown hairs. Antennal segment III equal to IV plus V; VI short, with unguis thumb-shaped.
colony
Alate (winged) viviparous female: body 6 mm long, abdomen 3 to 5 mm in diameter, head to tip
of folded wings 10 mm; wing expanse 18 mm, antennae 3 mm, posterior legs 11 mm. Head
and thorax bluish black, antennae and cornicles black, dorsum of abdomen whitish with 2 rows
of black spots on each side of the median line and a transverse series of small, black dots on
each segment. Cornicles short and truncate. Tips of femora, tibia and tarsi black. Body, legs
and antennae covered with long brown hairs. Wings dusky, especially toward base.
Oviparous females do not differ in appearance from viviparous females.
winged adult
Forewing.
Basswood - Tilia spp., hickory - Carya spp., oak - Quercus spp., pecan - Carya illinoensis (Wangenheim) Koch, sycamore - Platanus spp., walnut - Juglans spp. and wax myrtles (Barnard and Dixon, Mueller 2002).
During the late summer and autumn months, numerous specimens feeding on branches excrete
large amounts of a sticky, clear liquid known as honeydew that can form a sticky coating on
automobiles, picnic tables, lawn furniture, and plants underneath trees where the aphids are
feeding. Soon sooty mold, which is grey-black in color, begins to grow on the sugar-rich
honeydew. While sooty mold does not directly damage plants, it blocks sunlight and disrupts
photosynthesis, contributing to reduce plant vigor. Sooty mold can also damage the finish on
cars, chairs, tables or other objects.
Look for sooty mold on any of the host plants. Check the bark of limbs and trunk for large
dark aphids during the summer and early autumn.
Insect Management on landscape plants
- Barnard EL, Dixon WN. (October 1983). Giant bark aphid. Insects and Diseases:
Important Problems of Florida's Forest and Shade Tree Resources. http://www.fl-dof.com/Pubs/Insects_and_Diseases/insects_hbs_giant_bark_aphid.htm (9 June 2003).
- Harris TW. 1841. A Report on the Insects of Massachusetts, Injurious to Vegetation. (1842
Reprint: A Treatise on Some of the Insects of New England, Which are Injurious to Vegetation.
Cambridge), 459 p.
- Mueller CW. (March 2002). Giant bark aphids. Horticulture Update.
http://aggie-horticulture.tamu.edu/extension/newsletters/hortupdate/mar02/art2mar.html (9 June 2003).
- Thomas C. 1879. Eighth report of the state entomologist on the noxious and beneficial
insects of the State of Illinois. Third Annual Report, 212 p.
- Weed CM. 1891. Fifth contribution to a knowledge of certain little-known Aphididae.
Insect Life 3: 285-293.
- Wilson HF. 1909. Notes on Lachnus caryae Harris under a new name. Canadian
Entomologist 41: 385-387.
Author: H.A. Denmark, Florida Department of Agriculture and Consumer Services, Division of
Plant Industry.
Originally published as DPI Entomology Circular 212. Updated for this publication.
Photographs and drawing: Lyle J. Buss, University of Florida; Louis Tedders, ForestryImages.org; and Division of Plant Industry
Project Coordinator: Thomas R. Fasulo, University of Florida
Publication Number: EENY-292
Publication Date: June 2003. Latest evision: May 2004.
Copyright 2003-2004 University of Florida
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Department of Entomology and Nematology
Division of Plant Industry
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