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1、蜻蜓目 ODONATA,Common Names: dragonflies, damselflies 蜻蜓、豆娘 Distribution: Cosmopolitan Description Odonata is a very ancient order of insects with fossils dating from the Upper Carboniferous. Some species from this time period had 70 cm wingspans. Damselflies and dragonflies are very similar in appeara
2、nce but differ as follows: at rest, the wings of dragonflies are spread out perpendicular to the body (resembling aircraft wings), damselflies bring their wings together loosely over the back of the abdomen; dragonflies tend to be more strongly built insects, damselflies tend to be rather delicately
3、 built; dragonfly nymphs are heavily built mud-dwellers, while damselfly nymphs frequent tangled vegetation at the sides of the stream or pond and have two flattened abdominal appendages which are absent in dragonfly nymphs. All adults have short antennae composed of straight segments (filiform) and
4、 prominent compound eyes; simple eyes (ocelli) are usually present. The mandibles are well developed and all adult species are predatory on other aerial insects. The two pairs of wings are large, membranous and equal in size with prominent venation. Naiad There is no metamorphic cycle of egg, larva,
5、 pupa and adult. Instead the juvenile emerges from the egg as a wingless form of the adult (nymph) (hemimetamorphsis). However, the overall body shape may be much shorter and robust. A feature of dragonfly nymphs is the extendable lower lip (labium) or mask which is equipped with pincers. The labium
6、 is thrust forward very rapidly to secure prey. As they develop, dragonfly nymphs become capable of securing quite large prey including tadpoles and small fish. During development through a number of moults, wings begin to appear, but these are non-functional. At maturity, the nymphs move to the sur
7、face and emerge onto reeds or similar surfaces. The adult emerges by breaking through the nymphs final exoskeleton. The adult legs are used to capture aerial insects by forming a “basket“ in which the prey is first secured then transferred to the insects mouth. Food When in the aquatic phase, any su
8、itably sized animal is captured for food. This may include insects, tadpoles, fish, wrigglers, etc. Once the adult form is reached, most food is captured in flight and consists of other winged insects, particularly those associated with ponds or streams. Importance Dragonflies and damselflies form a
9、n extremely important group of predacious insects in stream and pond ecosystems. They are responsible for population control on a number of associated insect species. The adults are quite long lived and consume large quantities of insects over many weeks.,About 5000 species are recorded in the world
10、 ，and more than 400 species recorded in China.,等翅目 ISOPTERA,Common Names: termites, white ants 白蚁，白蚂蚁，螱 Distribution: Cosmopolitan, mostly tropical and subtropical Description There are about 2,300 species of these soft-bodied, social insects worldwide. Antennae are usually well developed and compos
11、ed of very short, bead-like segments (moniliform). Mandibles are always well developed. Compound eyes may be present but are frequently reduced. Termites have a series of castes: workers, soldiers, queens and kings. Soldiers form two main groups: those with well developed mandibles for defence again
12、st enemies and those with a pronounced “snout“ (nasus) through which sticky defensive secretions are ejected at the enemy. Wings are only present in reproductive castes and only for a short period. Wings are elongate, membranous and held flat over the body at rest. The wings have lines of weakness a
13、t their bases and are shed after dispersal from the termite mound. Many termite species consume wood or plant material but by themselves are incapable of cellulose digestion. Their gut flora contains symbiotic protozoans which are able to break down the cellulose and enable the termites to benefit f
14、rom their diet. NymphNo metamorphosis occurs (e.g. egg-larva-pupa-adult)(paurometamorphosis); the newly hatched individual is a wingless nymph and may develop into any caste required by the colony. FoodWood or plant material of any kind including grass stems, old weathered dung pats or plant litter.
15、 Cellulose is digested by symbiotic protozoans in the termite gut. Some termite species cultivate fungi on the stored cellulose and feed on the fruiting bodies produced. Importance The destructive effects of termites on buildings is well known. Huge sums of money are expended annually to prevent ter
16、mite infestations or to repair the damage done by these insects if they have invaded homes or other structures. Damage in tropical areas is especially severe unless care is taken with building design. Tropical species of Australian eucalypts actually benefit from termite infestation. Once the dead heartwood is removed by the termite colony, the living sapwood forms a rigid cylinder which remains quite strong, enough to support the weight of the tree. The resulting hollow is often used by various animals whose droppings provide quantities of fertilizer for the tree for many years.,
