Anoplura Blattaria Caelifera Coleoptera Collembola Dermaptera Diplura Diptera Embioptera Ensifera Ephemeroptera Heteroptera Homoptera Hymenoptera Isoptera Lepidoptera Mallophaga Mantodea Mecoptera Neuroptera Odonata Phasmatodea Plecoptera Protura Psocoptera Siphonaptera Strepsiptera Thysanoptera Thysanura Trichoptera
Insects represent about 80% of all of the animal kingdom; we know more than a million of species and this number increases day by day with the progress of the entomological research. But it is also true that we often use the word "insect" speaking of animals that are not properly insects.
Insects can be distinguished from other animals because they are invertebrate and adults have 3 pairs of legs. Spiders and Millepede for example, are not insects because they are invertebrate too but have more than 6 legs, on the contrary they respectively belong to the class of Aracnida and of Diplopoda.
The body of adult insects is divided in three sections:
- abdomen (usually divided in 11 segments, but are not more than 6 in collembola).
On the head there are the antennae (sensorial organs) variable in form and length, two compound eyes (formed by many eyes called ommatidia) and/or the ocelli (simple eyes), and the mouth parts which can be fitted for chewing, lapping or for sucking. The respiratory system is "tracheal", a system of small tubes communicating with outside assures the oxygenation of the internal tissues. They have the circulation of the blood and a heart.
Most of insects are oviparous, they lay eggs, but there are also viviparous insects procreating living insects and ovoviviparous insects, the incubation of eggs is internal and therefore the eggs open when they are laid. Most of insects are subject to metamorphosis process which according to the species can be complete or not, in fact the pupa phase (in the meaning of phase preceding adult phase in which insect doesn't eat; notice that some authors use the word nymph to indicate the phase in object instead of the larva of insects with incomplete metamorphosis) might be missing. Generally we individualize the following phases: egg, larva, pupa (or chrysalid) and adult. For example, in species of caelifera and ensifera the metamorphosis is not complete; the larva, which is very similar to the adult, is subject to many moults before it become an adult.
Each (species of ) insect is identified by a complex system of classification [animalia kingdom is divided in phylia, classes (insects are the most numerous class of phylum arthropoda), orders, families, genus and species] involving the knowledge of technical terms and the use of suitable instruments, but for our purpose, which is to identify the order and eventually the family, it is sufficient a visual examination of the morphology which can be carried out using a cheap camera and therefore without capturing and maltreating insects.
Here it is the list of the orders of Italian insects. The name of orders is the Latin one and, when available, there is also the link to the photos (in the legend there are the scientific name of order and suborder in black, family in blue; genus, species and subspecies in brown, and the common name in green). Photos were taken in Catania and Pedara (Sicily), some were taken in different place but in that case it is shown.
Anoplura (Sucking lice) (2)
Morphological distinctive characters: flat body, small head, without wings, short antennae, mouth parts are suited for piercing. They are parasite of mammals and of man too. See fig. B
Morphological distinctive characters: body is flat, antennae are long, abdomen ends with two appendages (cerci) and males have other two smaller appendages. Generally they have 2 pairs of wings and front ones are thick. Mouth parts are suited for chewing.
Morphological distinctive characters: front femora are long and strong fitted for leaping, antennae are short, females have a very short ovopositor. Generally they are winged but hind wings are membranous while front wings (tegmina) are coriaceous and unfitted for flying.
Morphological distinctive characters: front wings are coriaceous (elytra), mouth parts are suited for chewing.
Collembola (Springtails) (1)
Morphological distinctive characters: small insects without wings, usually they have a springing organ (furcula) kept under the abdomen when at rest. Springtails have always a ventral tube located under the first abdominal segment.
Morphological distinctive characters: abdomen ends with appendage like forceps.
Diplura (Diplurans) (1)
Morphological distinctive characters: without wings, without eyes, they live in the ground, the abdomen ends with two appendages (cerci) sometimes like forceps (but in this case you can distinguish them from Dermaptera because their tarsi have only 1 segment).
Diptera (True Flies, Mosquitos)
Morphological distinctive characters: generally they are winged, but only the front wings are suited for flying while hind ones are small and function as a balancing system (halteres), antennae usually are short. The biggest species wingless belong to the families Hippoboscidae and Nycteribiidae and are parasite of mammals, those of family of Braulidae are very small and parasite of bees.
Morphological distinctive characters: they are small insects with an elonged body and the first segment of front tarsi enlarged y modified for silk production; the silk is used in nest construction. Mouth parts are suited for chewing. Males can be winged.
Morphological distinctive characters: front femora are long and strong, fitted for leaping. Antennae, except in species of family Gryllotalpidae, are long as the body or more; females have a very long ovipositor. Generally they are winged but hind wings are membranous while front wings (tegmina) are coriaceous and unfitted for flying.
Ephemeroptera (Mayflies, Fishflies)
Morphological distinctive characters: generally they are winged with four membranous wings, abdomen ends with two or three long appendages (cerci).
Heteroptera (True Bugs)
Morphological distinctive characters: mouth parts are suited for piercing, generally they are phytophagous. Scutellum (triangular plate between bases of wings) is well developed. Usually they are winged but most of the front wings (hemelytra) is coriaceous. In species belonging to the family of Scutelleridae the scutellum covers all of the abdomen and it could be confused with elytra of Coleopter but we must consider that between the two elytron at rest, in the species of Coleoptera where they are not welded together, we can see a longitudinal line and this can help us.
Homoptera (Cicadas, Aphids, Whiteflies, Leafhoppers, Treehoppers)
Morphological distinctive characters: mouth parts are suited for piercing (are phytophagous), generally they are winged and wings are membranous with a similar structure.
Hymenoptera (Ants, Wasps, Bees)
Morphological distinctive characters: generally they are winged with two pairs of membranous wings (hind ones are smaller) transparent or with purple or brown reflections. Mouth parts are suited for chewing or sucking and lapping. Females of Mutillidae, Tiphiidae and of some species of the superfamily Chrysidoidea are generally wingless. Formicidae are wingless too, but males and queens have wings up to the nuptial fly.
Belong to this order many species with social costume: bees, wasps, ants. In social structure there is the queen that is the only fertile female, males and female-workers; sometimes in the structure of ants there are also soldiers. Some species of ants bring up small aphides to get their sweet effluvia.
Morphological distinctive characters: elongated soft body, light colour; compound eyes are very small or absent but are well developed in males and females (females have a big abdomen); males and females are darker and have also two pairs of similar wings up to the nuptial flight. Are insects with social costume: there is a queen and a king too. Mouth parts are suited for chewing and most of them feed on wood.
Lepidoptera (Butterflies, Moth)
Morphological distinctive characters: generally they are winged with 2 pairs of wings covered by colored scales (species of Sesiidae have wings with few scales and for their look might be confused with hymenoptera), mouth parts are fitted for lapping like a spiral (species of Micropterygidae have mouth parts fitted for chewing). Females of some species of Limantriidae and mainly of Geometridae have only vestigial wings (body is hairy and/or covered by scales).
Lepidoptera, usually called butterflies, for their color and form are one of the most beautiful manifestation of nature. But not all of the lepidoptera have an elegant look, some species (for example those of Pterophoridae) are not so graceful.
Mallophaga (Biting lice) (2)
Morphological distinctive characters: flat body, big head, without wings, short antennae, mouth parts are suited for chewing. They are parasite of birds and mammals too. See fig. D
Morphological distinctive characters: front legs are stronger than hind ones and fitted to catch preys (tibias and femora have many thorns), mouth parts are suited for chewing.
Mecoptera (Scorpion flies)
Morphological distinctive characters: head with a long appendage in which there are mouth parts suited for chewing.
Neuroptera (Net-winged insects)
Morphological distinctive characters: they have four membranous wings; wings held roof like when at rest. Most of all are carnivorous. The three Neuroptera suborders (Megaloptera, Raphidioptera and Planipennia) are generally considered just as insect orders.
Odonata (Dragonflies, Damselflies)
Morphological distinctive characters: they have four membranous wings, mouth parts are suited for chewing, antennae are short, abdomen ends with appendages called cerci.
Morphological distinctive characters: big insects with elongated cylindrical body (just like a branch) or very flat (just like a leaf). Mouth parts are suited for chewing; are phytophagous.
Morphological distinctive characters: they have four membranous wings, hind wings have a caudal lobe, antennae are long and filiform, abdomen ends with appendages called cerci.
Protura (Proturans) (1)
Morphological distinctive characters: very small insects living in the ground, the body is elongate and slender, without antennae, without eyes, without wings, fore legs stretched forward. See fig. C
Morphological distinctive characters: they are very small insects with long and filiform antennae, mouth parts are suited for chewing. They live in building too, usually inside books. Some species are winged.
Morphological distinctive characters: body laterally compressed, without wings, short antennae, mouth part are suited for piercing. They are parasites of birds, mammals and of man too.
Morphological distinctive characters: very small insects: females look like worms and live inside insects (they are parasite) while males have broad antennae and are winged but fore wings are a bit like halteres of Diptera. See fig. E
Morphological distinctive characters: they have not wings and abdomen ends with three long appendages. Species without ocelli are sometimes considered as part of the distinct order of Zygentoma and those with ocelli as part of the order of Microcoryphia.
Morphological distinctive characters: very small insects with elongate body, mouth parts are suited for rasping and sucking, they usually live on vegetables, winged species have two pairs of narrow wings fringed with hair, the body is narrow and flat in wingless species.
Morphological distinctive characters: they might be confused with lepidoptera, but generally wings are covered with hair and their antennae are long as wings or more.
(1) Collembola, Diplura and Protura are considered by some authors as belonging to a different class, that of Entognatha (subphylum Hexapoda).
(2) Anoplura and Mallophaga are considered by some authors as suborders of the order Phthiraptera.
(3) Caelifera and Ensifera are considered by some authors as suborders of the order Orthoptera.