windsofkansas.com

Damelflies of Various Sizes

A Web Page by Roy J. Beckemeyer

Last Updated 29 December 2001 (Improved legibility of charts)


John W.H. Trueman and Richard Rowe, in the ODONATA Page on the Tree of Life site, discuss the sizes of living Odonata:

"...The wingspan of modern anisopterans ranges from less than 20 mm (eg, Nannodiplax rubra, Libellulidae) to more than 160 mm (eg, Petalura ingentissima, Petaluridae): those of modern Zygoptera range from about 18 mm (eg, Agriocnemis pygmaea, Coenagrionidae) to about 190 mm (Megaloprepus coerulatus, Pseudostigmatidae)."

The picture below depicts a variety of quite small and large damselflies (Odonata: Zygoptera) together at the same scale so that it is easier to see the relative sizes.

An assortment of damselfly specimens illustrating the range of sizes.  Scanned by Roy J. Beckemeyer from specimens in his collection.

Here are the measured dimensions of these particular specimens: wing lengths and maximum widths, and total length (front of head to end of abdominal appendages):

Species FW length, mm FW width, MM HW length, mm HW width, mm Total length, mm
Ischnura hastata

9.2

2.0

9.0

1.9

20.4

Agriocnemis pygmaea

10.3

2.4

9.6

1.9

20.0

Nehalennia integricollis

12.4

2.7

11.6

2.6

23.3

Hetaerina cruentata

28.0

6.2

26.7

5.6

45.9

Heteragrion eboratum

35.2

5.2

31.8

5.1

58.1

Archilestes grandis

35.2

6.5

34.3

6.7

56.4

Vestalis gracilis

42.0

10.3

40.3

10.3

60.4

Megaloprepus coerulatus

63.7

15.9

61.4

16.0

85.4

 

The chart below is a bar chart showing the damselfly dimensions as multiples of those of Ischnura hastata.  It can be readily seen that the wing dimensions increase more rapidly as the damselfly size goes up than do the body length dimensions.  This might be expected, as the mass, and thus the weight of the insect increases as the volume, which is proportional to the cube of the linear dimensions.  The lift generated by the wings is proportional to the wing area, which increases as the square of the dimensional change.  Thus a "disproportionate" increase in wing size would help to keep the wing loading from becoming too high.


The following graph shows the same information in a different form.  Here the lines show the wing dimensions increasing faster than the body length as one goes from small to large damselflies.



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