The belief that the brown recluse spider carries its young, or spiderlings, on its back is a persistent misconception that often causes alarm. This spider, known for its reclusive nature, does not exhibit this form of maternal care. Understanding its actual reproductive cycle and contrasting it with the behavior of other spiders clarifies why this myth circulates.
The Definitive Answer: Brown Recluse Reproduction
The reproductive strategy of the female brown recluse involves creating and guarding an egg sac rather than physically transporting her offspring. The female constructs a silken container that is typically pale white or tan and approximately one-quarter inch in diameter. This spherical sac is usually placed in a sheltered location, often hidden within the irregular webbing or debris where the spider lives.
A single female can produce between one and five of these egg sacs during her lifetime, with each sac containing an average of 40 to 50 eggs. The time of year for egg-laying often peaks during the warmer months, from May through August. The mother remains near the egg sac, providing a measure of protection until the young are ready to emerge.
The development of the young spiders is completed entirely within the protective sac. After hatching, the spiderlings undergo at least one molt, or shedding of their exoskeleton, while still inside the silk casing. Once they reach the second instar stage, they emerge from the sac and immediately begin to disperse. They are fully independent individuals from the moment they leave, exhibiting no instance of being carried by the mother.
The Source of Confusion: Spiders That Carry Young
The likely origin of the belief that brown recluse spiders carry their young stems from the behavior of the Wolf Spider. Wolf Spiders are large, common, ground-dwelling spiders often mistaken for the brown recluse due to their similar brownish coloration. However, the Wolf Spider displays a distinct form of maternal care that directly aligns with the carrying behavior described in the common myth.
The female Wolf Spider’s reproductive cycle begins with her attaching her spherical egg sac to her spinnerets, the silk-producing organs at the rear of her abdomen. She carries this sac everywhere she goes, holding it aloft to keep it away from the ground and potential dangers. This behavior is the first stage of carrying, which is already a stark contrast to the brown recluse’s stationary egg sac.
The second stage of the Wolf Spider’s maternal care begins after the spiderlings hatch. The mother uses her fangs to tear open the egg sac, allowing the hundreds of tiny spiderlings to emerge. These newly hatched young then instinctively climb onto her back, where they cling to specialized hairs for several days. She continues to carry this dense cluster until they have undergone their next molt and are large enough to disperse.
Key Identification Features
Focusing on distinct physical characteristics is key to identifying a brown recluse. The most recognized feature is the dark, violin-shaped marking located on the dorsal side of the cephalothorax, the fused head and chest region. The “neck” of this violin shape points toward the spider’s abdomen, giving the species its alternate nickname, the fiddleback spider.
Another distinguishing characteristic is the eye arrangement, which is unique among common North American spiders. While most spiders possess eight eyes arranged in two rows, the brown recluse has only six eyes. These are organized into three pairs, or dyads, with a gap between each pair.
The body of the adult spider is relatively small, measuring approximately one-quarter to one-half inch in length. The coloration is a uniform light to dark brown. Importantly, the legs are slender and lack any stripes, bands, or large spines.