Cordulegaster sp. larva

Odonates are aquatic insects. They spend most of their life as larvae (nymphs) that live in water; this stage of their life cycle can last from a few months to a few years. Finally, they emerge from the water and metamorphose into adults in order to reproduce; their offspring return to the water and the cycle begins again.

This post features annotated images of a larva (nymph) from the Family Cordulegastridae (Spiketails) that was collected and reared by Bob Perkins. The larva died before it metamorphosed into an adult.

The distinctive jagged crenulations on the face mask of spiketails are unmistakeable!

Cordulegaster sp. larva (preserved specimen) | face-head

This individual is a female, as indicated by her developing ovipositor that can be seen on the ventral side of the specimen along the boundary between abdominal segments eight and nine (S8, S9).

Cordulegaster sp. larva (female) | ventral view

The presence of a ventromedial groove in the prementum is a reliable field mark for larvae/exuviae in Family Corduliidae (Emeralds). Some species of larvae/exuviae in other families of dragonflies, such as Family Cordulegastridae (Spiketails), feature a ventromedial groove in the prementum. In this case, the presence of a ventromedial groove does not indicate this specimen is an Emerald.

Most odonate larvae go through 10-13 stages of development known as “instars.” The author lacks sufficient experience to identify the instar of this specimen, although it appears to be one of the later stages as indicated by its well-developed wing pads, shown below.

Post Update: According to Ken Tennessen, author of Dragonfly Nymphs of North America: An Identification Guide, F-0 is the instar of this specimen (final instar). Thanks, Ken!

Cordulegaster sp. larva (female) | dorsal view

Larvae (nymphs)/exuviae in Family Cordulegaster (Spiketails) are burrowers, as indicated by the dirty, sediment-covered dorsal side and relatively clean ventral side of this specimen.

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Copyright © 2021 Walter Sanford. All rights reserved.

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2 Responses to “Cordulegaster sp. larva”

  1. Ángel Romero Martín Says:

    Hello Walter, how are the larval stages F4, F3 and F2 of Cordulegaster spp. larvae? Is there a publication to know the sex of the F4 and F3 larvae?
    Ángel Romero from Spain.

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