This is achieved by the male using his anal appendages to clasp the female between the
head and thorax, whereupon the female curves her abdomen round and under to make
contact with the accessory genitalia on the ventral surface of segments two and three of
the male's abdomen. This may be achieved very rapidly in flight (as frequently happens
in Libellula species), or the pair may fly into marginal vegetation, remaining together for
considerable periods of time. Prior to mating, males transfer sperm to their accessory
genitalia, by curling the tip of their abdomen under and forward, and they may also
clear sperm left from previous matings with other males from the genital duct of the
female before mating takes place.
Immediately after mating, females begin egg-laying. In this they may remain attached
to the males, in the well-known 'tandem' position (Fig. 2:4). This is often the case in
Fig 2.4 Pair of Damselflies (Enallagma cyathigerum) in 'tandem' position
some darter species, such as Sympetrum striolatum (the Common Darter), egg-laying
being accomplished as the tip of the female's abdomen is repeatedly 'flicked' under the
surface of the water while the pair fly over a pond or ditch. Tandem egg-laying is also
characteristic of a number of species (such as Pyrrhosoma nymphula, the Large Red
Damselfly) in which the female lays her eggs one by one 'endophytically' (i.e. in the
tissue of water plants). The male is held upright and motionless as she does so,
intermittently flying the pair on to another egg-laying station. Another pattern of
behaviour during egg-laying is commonly exhibited by some darter species (such as
Orthetrum spp.). In these cases the female lays her eggs freely along the margins of a
pond or ditch, while the male remains closely in attendance, although physically
separate, driving off other males. Alternatively, females may be observed egg-laying
quite unaccompanied by males. Though certain of these patterns may be typical of
some species, there is great variability not only from species to species, but also within
species, and for the same individual at different times. Eggs are laid in huge numbers,
from several hundred per episode in damselfly species, to as many as several thousand
in Anisopteran species.
The Dragonfly Life-Cycle
In some species the eggs hatch within five to forty days, hul in others (especially
species of Aeshna. Sympetrum and Lestes) development is delayed, and the egg over-
winters. Development in the spring is regulated by temperature, combined in some
species with sensitivity to day-length.
Dragonfly development takes the form of a series of aquatic larval stages or 'instars'.
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