Common Insect Species of Northwestern Ontario





Class Arachnida

Subphylum Chelicerata

Spiders are arthropods and members of the Subphylum Chelicerata. These organisms do not have antennae or wings. They normally have six pairs of appendages, the first pair being chelicerae, jaw-like structures, and the rest are leg-like. The body usually consists of two main regions, the front one called the cephalothorax and the hind one called the abdomen.

Spiders and their close relatives are placed together in the Class Arachnida, which includes the scorpions, harvestmen or daddy longlegs, ticks and mites, and a few other less well known groups. The spiders are a large diverse group (more than 2,500 North American species) and often very abundant in some habitats.

Dock Spider The cephalothorax normally bears six or eight simple eyes, mouthparts, including the fang-like chelicerae that are connected to venom glands, and legs. The abdomen has the genital structures, anus, and spinnerets through which various types of silk are drawn. A pair of pedipalps located behind the chelicerae serve as food crushing structures, and as the mating organ of the males. Behind the pedipalps are four pairs of legs which are used for pulling out silk strands from the spinnerets, web spinning, capturing prey, and many other functions.

Among the abundant spider species of northwestern Ontario the largest is the fishing spider, Dolomedes, also known as the dock spider as they live near water. They may walk on the water surface or dive beneath where they feed on aquatic insects or small fish. Colourful crab spiders (Family Thomisidae), somewhat crab-like in shape, frequently sit on flowers and ambush their prey, such as honey bees. Among the many ground species are the wolf spiders (Family Lycosidae) that forage for their prey, a common species being Trochosa terricola.

Crab Spider Wolf Spider

The well known orb webs spun onto foliage are constructed by large garden spiders that have bright yellow, white and black colour patterns. A host of other species weave unique webs for capturing prey of all sorts, flying insects, and arthropods that live in various dry land habitats.

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