Life cycle
Odonata are hemimetabolous insects, which undergo three distinct stages throughout their life, namely egg, larva and adult.
1. Larva
Most larvae of Odonata are aquatic. From the first to the last instar, individuals of some species could have moulted for up to fifteen times. Larvae of Odonata are carnivorous. They prey on aquatic insects, tadpoles, and even small fish. Photos below are the larvae of two species of dragonflies (Anisoptera) respectively.
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2. Emergence
Emergence is a process in which the larva transforms into an adult. This process usually occurs at dawn and dusk. Bodies of freshly-emerged individuals are soft, and with paler color. The photo below is a freshly-emerged Common Bluetail.
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After body and wings hardened, the adult flew away, leaving an exuviae behind. The photo below is the exuviae of a Small Dragonhunter.
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If the larva is subject to collision during emergence, its wings might be unable to stretch completely, affecting its flying ability. Photo below shows a Common Blue Skimmer with emergence failure.
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3. Adult
3.1. Subadult
Freshly-emerged adult is yet to be mature, and is regarded as subadult, which lasts for less than two weeks usually. Subadult males of some species look like female. For example, the photos below show the subadult males of a Crimson Darter and a Common Blue Skimmer respectively.
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In some species, the synthorax of an adult becomes pruinose after being completely mature, such as the male of Marsh Dancer. The photo below shows the subadult male of a Marsh Dancer, in which the synthroax is yet to be pruinose.
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In some species, there are apparent differences between subadult and adult male or female, such as the subadult male of a Scarlet Dwarf. However, its shape is similar to an adult male, as shown below.
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3.2. Predation
Adults of Odonata usually prey on insects smaller than themselves. Photos below show a Common Red Skimmer and a Forest Chaser having their meal.
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Besides, members of Odonata with larger body size prey on smaller species. Photos below show a Green Skimmer preying on an Elusive Adjutant and an Ochre Titan preying on a Black-banded Gossamerwing.
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3.3. As a Prey
In the middle of the food chain, Odonata are prey for predators from upper level. The photo below (taken in Taiwan) shows the scene of a Common Red Skimmer being eaten by a spider.
3.4. Parasite
Members of Odonata can be infected by parasites, such as the Red-faced Skimmer and the Red-veined Darter in photos below.
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3.5. Reproduction
A pair of connected Blue Forest Damsels waiting for copulation: The male uses its anal appendages to clasp back of the female head or prothroax.
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A Common Red Skimmer mistakenly connected with Emerald Cascader.
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Regal Pond Cruisers during copulation: The male uses its anal appendages to clasp the back of the female head or prothroax, while the female abdomen tip is attached to the secondary sexual organ of the male at the second abdominal segment.
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All damselflies (Zygoptera) and Aeshnidaes adopt endophytic oviposition, such as the Giant River Hawker in the video. These species have saw-like ovipositor, and lay eggs into soil or plants.
Some species of Libellulidae adopt exophytic oviposition, such as the Common Red Skimmer in video. In the video when the female was laying eggs, the male was guarding around, preventing other males from approaching.
3.6. Aged
Aged individuals may show different body features, such as the synthorax and abdomen tip becoming pruinose white to a large extent in Indochinese Copperwing; synthorax dorsum and abdomen becoming pruinose blue in female of Lesser Blue Skimmer; yellow stripes in synthorax sides becoming dark brown in Emerald Cascader.
