Rain spiders

Published on September 16th 2020
A close up of a spider
Rain spiders are often seen in or around the garden and house where people are scared by their big and sometimes unexpected appearance.
A close up of a spider
However, they are not venomous and a bite will be similar to a bee sting. Interestingly, these spiders were previously listed as potentially dangerous. Tests with guinea-pigs were performed and found that they died after three minutes after a bite. Consequently, the guinea pigs died of shock and not spider venom. Although they are considered harmless to humans, they will lift their two front pairs of legs and show their chelicerae (mouthparts), to scare off any potential enemies.
Another common phenomenon often observed in the garden, is the egg sac which is constructed by the female spider. This is common in the months from November to April. The egg sac is a roundish bag made of silk with twigs and leaves woven together with a size of up to 100 mm.
A bird sitting on grass
Egg sac
The construction of this egg sac and the laying of the eggs take up to 5 hours. The eggs hatch inside and are protected within the egg sac. During this period, the female guards the egg sac aggressively. Therefore, when you work in the garden, do not touch the egg sac, because the female will defend her brood and will bite to protect it. After 21 days the spiderlings will chew their way out of the egg sac. A female spider can construct about 3 egg sacs in her 2-year life.
A close up of a flower
Fly on camomile
These spiders feed on a variety of insects, which include flies, moths, grasshoppers, crickets, etc. They also feed on lizards and are often called lizard-eating spiders. They are known as rain spiders because they take shelter from the rain. That is why you often see them inside homes before and during rainy weather.
Another common phenomenon seen in gardens is the spider-hunting wasp, a pompilid wasp (Tachypompilus ignites) which paralyze the rain spider with a sting. The wasp will drag the spider to her burrow in which she will lay an egg.
Sometimes people are frightened by the old skins of the rain spiders, because they look almost identical to the real spider, except that the abdomen is crumpled. The rest of the old skin is completely intact. In order for spiders to grow, they need to shed their old skin, because the exoskeleton cannot expand or grow. The exoskeleton is there to protect the spider. The spider will secrete a moulting fluid between the old and new exoskeletons which makes it easier for them to separate. Younger spider swill moult more frequently.
When you see these spiders in your home, please do not kill them.
Rather catch them with a container and release them outside in your garden, so that they can help you with pest control. Spiders are important pest control agents and you can benefit from their existence.

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