When people search for “red spiders,” they often encounter a diverse group of small, reddish arachnids. These creatures can range from true spiders to other related arthropods. This article explores the common types of red arachnids people might encounter and their typical activities.
Identifying “Red Spiders”
Many people confuse true red spiders with spider mites, which are distinct types of arachnids. True red spiders, such as the red house spider (Nesticodes rufipes) or certain jumping spiders like Phidippus cardinalis, possess eight legs and two distinct body segments: a cephalothorax and an abdomen. The red house spider typically has a reddish-brown body and legs, with a globe-shaped abdomen that can sometimes feature a red band or spots. Jumping spiders are often more compact with a solid red back or abdomen.
Spider mites, conversely, are not true spiders but belong to the family Tetranychidae, making them closer relatives to ticks. The two-spotted spider mite (Tetranychus urticae) is a common example, and while they can appear greenish or yellow, they often take on a reddish or orange hue. These mites are significantly smaller than true spiders, often less than 1 millimeter in size, appearing as tiny moving dots to the naked eye. Their oval bodies and the fine, silken webbing they produce on plants are key distinguishing features.
Daily Life and Habits
The daily lives and habits of true red spiders and spider mites differ. True red spiders, such as the red house spider, are predatory and primarily feed on insects and other small arthropods that become ensnared in their webs. Jumping spiders are also active hunters, using their keen vision and jumping ability to ambush prey like flies and other insects. These spiders typically lay eggs in sacs, with red house spiders producing round egg sacs kept near their tangled webs.
Spider mites, in contrast, are herbivores, feeding exclusively on plant cells by piercing leaves with their needle-like mouthparts and sucking out the fluids. This feeding causes characteristic stippling or discoloration on plant leaves. Their reproductive cycle is rapid, especially in warm, dry conditions, where a single female can lay numerous eggs daily, leading to quick population growth. Spider mite eggs are typically spherical and laid on the undersides of leaves, hatching into larvae and then nymphs before reaching adulthood. While true spiders move by running, walking, or jumping, spider mites move slowly across plant surfaces, using their fine silk webbing primarily for protection and dispersal, rather than for trapping prey.
Interaction with Humans and the Environment
The interactions of these red arachnids with humans and the environment vary. Spider mites are agricultural and garden pests due to the damage they inflict on plants. Their feeding can lead to yellowed leaves, stippling, and reduced plant growth, impacting a wide range of crops and ornamental plants. True red spiders, conversely, are not considered pests and can even be beneficial by preying on other insects within homes and gardens.
Spider mites do not bite humans or pets, as their mouthparts are designed solely for feeding on plant tissues. Any minor skin irritation attributed to spider mites is incidental. True red spiders, like the red house spider and jumping spiders, can bite humans, but such occurrences are rare and happen only when they feel threatened or are accidentally pressed against skin. Bites from these spiders are mild, often comparable to a mosquito bite, and are not considered dangerous to humans, resulting in only minor localized irritation. Managing spider mites often involves cultural controls like adequate irrigation and sometimes insecticidal soaps or oils, while true spiders are rarely a nuisance requiring active management beyond simple removal.