Chalk-fronted corporal (Libellula julia)

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Chalk-fronted corporal fact file

• Description
• Biology
• Range
• Habitat
• Status
• Threats
• Conservation
• Find out more
• Glossary
• References
• Print factsheet

Chalk-fronted corporal description

The chalk-fronted corporal (Libellula julia) is a distinctive dragonfly with two white bars on the front of its thorax, which are similar in appearance to the white shoulders on a corporal’s uniform, giving this species its common name ^{(2) (3)}. The male has a white powder-like surface on the upperside of the thorax and front section of the abdomen ^{(2) (3) (4)}, although the posterior of the abdomen is black ⁽³⁾. As with other members of the Libellula genus, this species has a stout body and a wide, flat abdomen ⁽⁴⁾. The wings are clear apart from a small, triangular brown spot at the base of each hindwing ^{(3) (4)}. The face is brown and the forehead is grey ⁽³⁾.

The female chalk-fronted corporal is considered to be a rather plain dragonfly ⁽³⁾. It is relatively similar in appearance to the male, but is pale brown and has a grey powder-like appearance on the upperside of the central segments of the abdomen, rather than white ^{(2) (3) (4)}. Some females have been known to develop a similar white powdery appearance to the male ⁽³⁾. The juvenile chalk-fronted corporal is brown with a black stripe which extends along the upperside of the abdomen. It has the same white patches on the front of the thorax as the adult ⁽³⁾.

Size

Length: 4 - 4.5 cm ⁽²⁾

Wingspan: 6 - 7 cm ⁽²⁾

Chalk-fronted corporal biology

Very little is known about the biology of the chalk-fronted corporal. Its flight season runs between mid-May and late October ⁽³⁾, although in California it is mostly seen between June and August ⁽²⁾. This species forages in open woods, perching on the ground and in low vegetation ⁽³⁾. As with all dragonflies, it can be assumed that the chalk-fronted corporal is a highly skilled predator and detects its prey mainly by sight. All dragonflies are opportunistic and generalised predators, with small flying insects being the primary component of their diet ⁽⁵⁾.

The male chalk-fronted corporal is highly territorial ⁽²⁾. When a female dragonfly enters the male’s territory, the male chases the female and then forms a ‘wheel’ position. This is a characteristic position formed by all dragonflies during copulation, which consists of the male grasping the female’s head with a claw-like appendage at the base of its abdomen. Egg laying follows shortly after copulation, with the female depositing the fertilised eggs into water. Female dragonflies are able to store live sperm in their body for days and any new copulation may displace the sperm from the previous mate, so many male dragonflies defend the female until the eggs are deposited ⁽⁵⁾.

The eggs of dragonflies hatch into aquatic larvae, which are voracious predators and possess extendible mouthparts with hooks on the tips. When the mouthparts are extended, these hooks grip the prey and return it to the mouth. The larvae eventually metamorphose into the adult form ⁽⁵⁾. 

Chalk-fronted corporal range

The chalk-fronted corporal is found in southern Canada and the northern United States ^{(2) (3)}. 

Chalk-fronted corporal habitat

The chalk-fronted corporal is found around bogs, swamps, lakes and slow streams ^{(3) (4)}. This species prefers areas with acidic water and floating vegetation, on which it frequently perches ^{(2) (3)}.

Chalk-fronted corporal status

The chalk-fronted corporal has yet to be classified by the IUCN.

Chalk-fronted corporal threats

There are not known to be any major threats to the chalk-fronted corporal at this time.

Chalk-fronted corporal conservation

There are not known to be any specific conservation measures currently in place for the chalk-fronted corporal.

Find out more

Find out more about dragonfly and damselfly conservation:

• Moore, N.W. (1997) Dragonflies: Status Survey and Conservation Action Plan. IUCN/SSC Odonata Specialist Group, IUCN, Gland, Switzerland and Cambridge, UK. Available at:
  http://data.iucn.org/dbtw-wpd/edocs/1997-042.pdf

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Glossary

Abdomen

In arthropods (crustaceans, insects and arachnids) the abdomen is the hind region of the body, which is usually segmented to a degree (but not visibly in most spiders). In crustacea (such as crabs), some of the limbs attach to the abdomen; in insects the limbs are attached to the thorax (the part of the body nearest to the head) and not the abdomen.

Fertilisation

The fusion of gametes (male and female reproductive cells) to produce an embryo, which grows into a new individual.

Genus

A category used in taxonomy, which is below ‘family’ and above ‘species’. A genus tends to contain species that have characteristics in common. The genus forms the first part of a ‘binomial’ Latin species name; the second part is the specific name.

Larva

Immature stage in an animal’s lifecycle, after it hatches from an egg and before it changes into the adult form. Larvae are typically very different in appearance to adults; they are able to feed and move around but are usually unable to reproduce.

Metamorphosis

An abrupt physical change from the larval to the adult form.

Territorial

Describes an animal, a pair of animals or a group that occupies and defends an area.

Territory

An area occupied and defended by an animal, a pair of animals or a group.

Thorax

Part of the body located between the head and the abdomen in animals. In insects, the three segments between the head and the abdomen, each of which has a pair of legs. In vertebrates the thorax contains the heart and the lungs.

References

1. Species 2000 and ITIS Catalogue of Life (June, 2012)
   http://www.catalogueoflife.org/
2. Manolis, T. (2003) Dragonflies and Damselflies of California. University of California Press, California.
3. Dunkle, S.W. (2000) Dragonflies Through Binoculars: A Field Guide to Dragonflies of North America. Oxford University Press, Oxford.
4. Giberson, D. and Dobrin M. (2000) Dragonflies and Damselflies of Prince Edward Island National Park. Watershed Research Group, Prince Edward Island, Canada.
5. O’Toole, C. (2002) The New Encyclopedia of Insects and Their Allies. Oxford University Press, Oxford.