PHYLLIUM SICCIFOLIUM LEAF INSECT
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PHASMID STUDIES (PDF) ![]() CLICK FOR DOWNLOAD --------------------------------- Classification Phylum Arthropoda Class Insecta Order Phasmatodea Superfamily Phyllioidea Family Phylliidae Genera Phyllium
.............................. Keys for Identification of Immature Insects (PDF)CLICK FOR DOWNLOAD |
LEAF INSECT / PHYLLIUM
The family Phylliidae (often misspelled Phyllidae) contains the extant true leaf insects or walking leaves,
which include some of the most remarkably camouflaged leaf mimics in the entire animal kingdom. They occur from South Asia
through Southeast Asia to Australia. At present, there is no consensus as to the preferred classification of this group;
some sources treat Phylliidae as a much larger taxon, containing the members of what are presently considered to be several
different families.
Leaf insects are camouflaged (using mimicry) to take on the appearance of leaves. They do this so accurately that predators
often are not able to distinguish them from real leaves. In some species the edge of the leaf insect's body even has the
appearance of bite marks. To further confuse predators, when the leaf insect walks, it rocks back and forth, to mimic a
real leaf being blown by the wind.
Leaf insects measure roughly 28 to 100 mm (1.1 to 3.9 inches) in body length. Females of the largest known species, Phyllium
giganteum, may exceed 100 mm. Males tend to be smaller than females. In addition, females typically have large forewings
(elytra, or tegmina) that lie edge to edge on the abdomen. They also tend to lack hind wings and usually are flightless.
The male, by contrast, has small forewings and non-leaflike (sometimes transparent), functional hind wings. Females may
reproduce by parthenogenesis when males are absent. Females flick or drop their eggs to the ground. Newly hatched young (nymphs)
are wingless and brown or reddish in colour. After hatching, they climb food plants, becoming green after feeding on leaves.
Leaf mimicry often is elaborate among the leaf insects, with the insects wings and legs closely imitating leaf colour and form.
Female elytra typically resemble, in their vein pattern, the midrib and veins in a leaf. Some species are even adorned with
markings that resemble spots of disease or damage, including holes. Nymphs may sway side to side, as though mimicking the
movement of a leaf in the wind. Leaf mimicry is thought to play an important role in defense against predators. Some species
possess rows of tubercles on their antennae that when rubbed together produce sounds that may also serve to ward off predators.
Leaf insects are related to the stick insects (order Phasmida; see walkingstick).
A 47-million-year-old fossil of Eophyllium messelensis, a prehistoric ancestor of Phylliidae, displays many of the same
characteristics of modern leaf insects, indicating that this family has changed little over time.
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