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New Jersey Endangered and Threatened Species Field Guide

Image of An adult male Williamson's emerald.Zoom+ An adult male Williamson's emerald. © Allen Barlow

Williamson's emerald

Somatochlora williamsoni

Species Group: Invertebrate

Conservation Status

State: Special Concern



Ranging from 2.3”-2.5” in length, this is a medium-sized striped emerald. The thorax has an alternating pattern of metallic green and bronze with inconspicuous yellow lateral markings. The abdomen is longer than the wings. The female is similar but has obscure yellow spots on the abdomen.

Image of Range of the Williamson's emerald in New Jersey.Zoom+ Range of the Williamson's emerald in New Jersey.


The preferred habitat for the Williamson’s emerald is slow streams and lakes where it can be found at slow moving boggy outlets. There are only a few records of this species scattered through three northern New Jersey counties. The full range is from New Brunswick, Canada in the north to Georgia in the south and west to Minnesota.


Larvae are predatory and adults feed on other flying invertebrates.


This species has been recorded in New Jersey from late May to Late July.


The Williamson’s emerald is considered a species of Special Concern in New Jersey due to its rarity.

Text derived from the book, Field Guide to Dragonflies and Damselflies of New Jersey. 2009. By Allen E. Barlow, David M. Golden and Jim Bangma. Edited and updated by Larissa Smith in 2011.

Scientific Classification

Kingdom: Animalia
    Phylum: Arthropoda
       Class: Insecta
          Order: Odonata
             Family: Corduliidae
                Genus: Somatochlora
                   Species: S. williamsoni

Find Related Info: Invertebrates, Special concern

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