Scytodes Thoracica – Spitting Spider

The spitting spider, scientifically called Scytodaes thoracica, is a fascinating type of hunting spider that captures and paralyzes its prey with sticky venomous silk strands that it shoots from its head. The spitting spider opccurs throughout the world and can be found in every U.S. State.

Spitting Spider Description

The spitting spider has a very characteristic look and the identification is generally very easy. The most telling characteristic is is body coloration. The entire body is a light brown with darker brown dots and patterns. The legs are light brown with several darker bands.

Scytodes Thoracica - Spitting Spider
The spitting spider has a very unique and recognizable body coloration. Photo: Martin Cooper

Another way to tell a spitting spider from other spiders is the size of abdomen and cephalothorax. Most spiders have a larger abdomen (the back part of the body). The cephalothorax of the spitting spider, on the other hand, is mostly larger than its abdomen. The cephalothorax is dome-shaped. A closer look at the eye area reveals that spitting spiders only have six eyes. Most other spiders have eight eyes. They form two groups of two eyes each. Two on top and one further down in the center.

Size

An adult female spitting spider reaches an average body size of 0.15-0.25 inches (4-6mm). They can reach a total leg span of around 0.75 inches (18mm). Male spitting spiders are slightly smaller than females.

Spitting Spider on hand for size comparison
A spitting spider on a hand for size comparison. Photo: Nikk

Scytodes thoracica Web

Most spiders have their silk glands, that they use to spin webs, on their abdomen. In addition to that, the spitting spider has two additional silk glands on their cephalothorax (head) that are connected to its venom glands. This allows the spider to spit silk strings from its head that are covered in a sticky, venomous liquid that paralyzes its prey.

Since the spitting spider is a hunting spider, it does not spin a web to catch flying or roaming creatures.

Spitting Spider Hunting Behavior

Below, you can see a video of the peculiar hunting behavior of the spitting spider. The spider starts hunting at nighttime. It slowly approaches small prey like insects or other spiders. Once it has moved into a range of 0.5-0.75 inches of the prey, it streches out one of the front legs to measure the distance to the prey. It does so with extreme caution without the prey noticing that is being watched. Once the exact distance is measured, the spitting spider emits to spurts of liquid, venomous silk over its prey that solidifies and shrinks in contact with air. This immediately captures and immobilizes the prey. The spitting spider continues spraying the prey until it is completely immobilized. After that, the spider moves in for a final bite before wrapping it up in silk.

Spitting Spider Bite

It spits venomous silk on top of it and paralyzes the small insects or spiders that it hunts. For humans, the spitting spider is absolutely harmless. The spitting spider only spits its venomous silk onto immobile, small animals and would not attack a larger pet or a person. And even if it would, the venom on the silk would not be strong enough to cause any reaction. Its fangs are not strong enough to pierce through human skin.

Spitting Spider Range in the USA

The spitting spider can be found throughout the world and occurs in every U.S. state. Sightings of spitting spiders are more common in the Eastern United States but occassionally, specimen are also seen in the Western United States. It is still unclear whether the spider is native to the Western U.S. or if sightings only occur from imported specimen. However, it is not unlikely that you will encounter a spitting spider in any of these states: Alabama, Alaska, Arizona, Arkansas, California, Colorado, Connecticut, Delaware, Florida, Georgia, Hawaii, Idaho, Illinois, Indiana, Iowa, Kansas, Kentucky, Louisiana, Maine, Maryland, Massachusetts, Michigan, Minnesota, Mississippi, Missouri, Montana, Nebraska, Nevada, New Hampshire, New Jersey, New Mexico, New York, North Carolina, North Dakota, Ohio, Oklahoma, Oregon, Pennsylvania, Rhode Island, South Carolina, South Dakota, Tennessee, Texas, Utah, Vermont, Virginia, Washington, West Virginia, Wisconsin, Wyoming

Scytodes thoracica Scientific Classification

  • Kingdom: Animalia
  • Phylum: Arthropoda
  • Subphylum: Chelicerata
  • Class: Arachnida
  • Order: Araneae
  • Infraorder: Araneomorphae
  • Family: Scytodidae
  • Genus: Scytodes
  • Species: Scytodes thoracica
Scytodes Thoracica – Spitting Spider

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