Fireflies are actually flying beetles. They have a special chemical in their bodies that allows them to flash a signal to attract a mate.

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Sac Spider Sac Spider stalking and capturing a cricket
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Bug Types

‘Bug’ is a name that is given to many invertebrate animals, or animals that do not have a backbone. Mostly it is used to describe those invertebrate animals that have a segmented, hard outer skeleton and jointed legs. These animals are called arthropods and include insects, spiders, mites, scorpions, millipedes, centipedes and crustaceans.

Bugs are Arthropods

Arthropods belong to the group or phylum Arthropoda, and their tough, armour-like covering is called an exoskeleton. The bodies of arthropods comprise several main divisions. Insects have three body divisions, spiders have two body divisions, while centipedes and millipedes have many small body divisions. Arthropods also have jointed legs.

The number of legs and body divisions are used to classify bugs into smaller classes: Insects, Arachnids, Myriapods and Crustaceans.


Insects belong to the class Insecta. All adult insects have three body divisions, six legs and a pair of feelers, or antennae. The three body divisions of an insect are the head, thorax and abdomen. The head carries the eyes, the mouthparts and the antennae. The central body region, or thorax, has the legs attached—and wings, if there are any. The rear section, or abdomen, carries the insect's digestive and reproductive organs.


Spiders are not insects. They belong to the class Arachnida, which also includes scorpions, ticks and mites. The bodies of arachnids are divided into two distinct regions. The head and thorax are fused together in the front section, called the cephalothorax, which attaches to the abdomen. All arachnids have eight legs attached to their cephalothorax, and all lack antennae and wings.


Centipedes and millipedes belong to the group Myriapoda. They have a pair of antennae, many small body segments and many legs. Centipedes and millipedes differ in that centipedes have one pair of legs per body segment while millipedes have two.


Arthropods in the class Crustacea are mostly marine creatures, such as crabs and crayfish. While they are not generally called bugs, other crustaceans are. Slaters or woodlice are crustaceans. They have a variable number of legs (at least ten), two pairs of antennae, three body sections and limbs that branch in two


Invertebrate animals that are soft-bodied and without legs are not usually considered to be bugs. Worms belong to a phylum called Annelida. Slugs and snails belong to the phylum Mollusca.

 Millipedes  Centipedes
 Slaters  Snails
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Green Carabid Beetle, link to large image Green Carabid Beetle

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Sac Spider, link to large image Sac Spider

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