Latrodectus sp.

Often construct their webs close to the ground. The webs are very irregular in construction. The centre of the web is usually located under a stone or branch or in a crack in a wall and forms a basket-like recess which the spider retreats into.

Found in the most varying habitats but usually avoid forested areas. They live in both farmed and unfarmed regions and in some regions are even found in cities. L. tredecimguttatus appears to prefer grain fields in southern Europe. L. mactans, L. hesperus and L. hasselti are frequently found in and around human habitations, e.g. in tool sheds, garages, cellars or outdoor toilets, but also in wood or junk left lying around.

Round abdomen. The cephalothorax (head and anterior part of the body) appears small in comparison. Body length in females 1–1.8 cm, in males barely more than 0.5 cm.

Colouring from shiny black to brownish. L. mactans and L. geometricus possess a red marking in the form of an hourglass.

L. geometricus also has markings in the form of geometrical patterns on the dorsal surface of the abdomen. In L. hasselti and L. indistinctus there is usually a red or orange longitudinal stripe along the dorsal surface of the abdomen. In L. tredecimguttatus with several red spots distributed over the dorsal surface of its abdomen or there may be none at all.

No particular defense behaviour.

Widow spiders are not at all aggressive and practically only ever bite when squashed. This can happen if they get stuck between a piece of clothing and the victim's skin or when carelessly picking up tools, bundles of grain etc.

Loxosceles sp.

Shy, primarily nocturnal spiders. Irregular web with cotton-like threads.

Prefer dark hiding places outdoors, e.g. under stones, in cracks in stones, under loose bark, under fallen leaves etc. Several species, such as L. laeta and L. rufescens, often live close to humans, in houses, cellars, sheds, barns or animal sheds.

Body length 0.8–1.5 cm. Colouring generally light to dark brown. In many species there is a distinctive, dark marking in the form of a violin on the cephalothorax.

No particular defense behaviour.

Brown spiders are unaggressive and only bite if squashed.

Phoneutria sp.

Nocturnal. Do not build webs, but rather actively hunt prey. Travel around in their search for prey and in doing so not uncommonly enter human habitations and adjacent sheds or similar buildings. At daybreak they hide themselves, for example in clothes or shoes.

Mainly in forested areas. P. nigriventer also abundant in banana plantations, where they hide in large dry leaves. By banana shipment P. nigriventer is introduced to Europe and other continents from time to time.

Body length up to 3 cm, leg length 4.5–6 cm, males smaller. Body covered with short hairs. Colouring greyish to brown-grey, chelicerae (venomous fangs) surrounded by red hairs at the base. Light-coloured marking on the upper surface of the abdomen.

Do not attempt to flee like most other spiders, but adopt a warning posture, with front legs raised high, erect upper body and raised chelicerae. In this typical defensive posture, the spider copies every movement made by the cause of the disturbance so that it is always facing it directly.

If approached too closely, they jump towards the offender and bite fiercely. Also, if you try to scare them away with a stick or similar object, they will climb up it towards you at lightning speed.

Atrax sp.

Build funnel-shaped webs in hollows in the ground, cracks in rocks etc. Atrax robustus, the medically most important species, are brought into urban areas of Sydney with firewood. Males wander, in particular during mating season in summer, in search of a female. During their wandering they may enter houses.

In Queensland these spiders prefer damp rainforest as their habitat, whereas in the more southern parts of their distribution area they are chiefly found in the drier eucalyptus forests.

Sturdy body with massive venomous fangs. Body length in A. robustus up to 4 cm (female animals) or up to 2.5 cm (male animals). Shiny black, hairless cephalothorax (head and thorax). Posterior part of the body without markings, dark blue to dark purple in males, pale in females. 8 eyes closely grouped. 2 prominent spinnerets which are located underneath the end of the abdomen.

When threatened they can be very aggressive and assume a defensive posture in which they raise their front pair of legs and their fangs.

Only males are known to cause severe envenoming. Male A. robustus are easy to recognise from the spurs on the second pair of legs.