Bates College Department of Biology

Daisy Diamond, Class of 2019

Daniel Levitis, PhD, Visiting Assistant Professor of Biology


We provide a dichotomous key, with photographs and illustrations, for distinguishing between instars of the pea aphid (Acyrthosiphon pisum) in the developmental pathway leading to the apterous parthenogenetic adult. Lengths of body, antenna and cauda are provided for a sample of each instar.

Additional Information

Primary Download: A PDF file containing a dichotomous key consisting of original line drawings, photomicrographs, and descriptions of the peas aphid apterous parthenogenic instars.

Secondary Download: A .zip file containing individual .jpeg images of each original line drawing and photomicrograph contained in the primary dichotomous key. The .zip file also contains an Excel .xlsx file that provides basic information about each image file.

Single Image Download: Individual images from the dichotomous key can be viewed and downloaded from the Image Gallery below.



Download Full Text (12.0 MB)

Download A compressed .zip file containing jpeg files of all pea aphid (Acyrthosiphon pisum) illustrations and photographs and an MS Excel .xlsx file with descriptions of each image. (9.0 MB)

Streaming Media


aphid development, nymphal stages, identification key, wingless aphid instars, Acyrthosiphon pisum, pea aphid

Creative Commons License

Creative Commons Attribution-Share Alike 4.0 International License
This work is licensed under a Creative Commons Attribution-Share Alike 4.0 International License.

Funding Source(s)

Bates Faculty Development Fund grant to D. L.

Portions of this work were completed in the Bates College Imaging and Computing Center which was established with support from the National Institute of General Medical Sciences of the National Institutes of Health (P20 GM-­‐103423).

Publication Date


Dichotomous Key to Pea Aphid (Acyrthosiphon pisum) Apterous Parthenogenic Instars

Open Access

Available to all.