“Daddy Long Legs” is a confusing common name referring to three distinct types of arthropods. This article focuses on the two arachnids most often associated with the name and egg-related questions: the Harvestman (Opiliones) and the Cellar Spider (Pholcidae). Understanding the differences in their eggs provides a clear way to distinguish between these two groups, which are not closely related despite their similar appearance. The third creature sometimes called a Daddy Long Legs, the Crane Fly (Tipulidae), is an insect whose eggs are rarely mistaken for the others.
The Eggs of Harvestmen (Opiliones)
Harvestmen (Opiliones) are not true spiders and lack silk glands, meaning they never produce an egg sac to house their young. The female uses a long, specialized tube called an ovipositor to deposit her eggs directly into protected locations. Therefore, any silken bundle found cannot belong to a harvestman.
The eggs are small, spherical structures, typically measuring between 0.5 and 1.0 millimeters in diameter. When freshly laid, their color is usually a pale white, yellow, or light green, often darkening slightly over time. The female lays these eggs individually or in small, loose groupings, sometimes depositing over a hundred eggs in a single session.
Deposition sites are chosen for moisture and protection from predators and environmental changes. Common locations include damp soil, under rocks or logs, within crevices in decaying wood, or beneath bark. The eggs possess a smooth surface coated with adhesive mucus, which helps them stick to the substrate and allows some species to cover them lightly with surrounding debris for camouflage. In some species, the male harvestman will exhibit paternal care, guarding the eggs until they hatch, which can take anywhere from a few weeks to several months depending on the temperature.
The Egg Sacs of Cellar Spiders (Pholcidae)
Cellar Spiders (Pholcidae) are true spiders, and their reproductive strategy involves constructing an egg sac using silk. The female wraps her eggs in a small, flimsy bundle of silk. This sac is not a tightly woven, dense sphere, but a loose, irregular white or yellowish webbing that allows the individual eggs inside to remain visible.
The eggs are small and pale, laid in batches that typically range from 13 to 60 eggs per sac. A distinguishing behavior of the female is that she does not abandon the sac in her web or attach it to a surface. Instead, the mother continuously carries the loose, silken bundle in her chelicerae (mouthparts) until the spiderlings hatch.
This maternal care means that any loose cluster of pale eggs found being actively carried by a long-legged spider is almost certainly a Cellar Spider egg sac. The female may produce several of these sacs over her lifetime. Once the eggs hatch, the tiny spiderlings often remain clustered near the mother for a brief period before dispersing to build their own loose, haphazard webs in secluded spots like basements and corners.
Identifying Common Look-Alikes
The small, pale nature of both Harvestman eggs and Cellar Spider sacs often leads to confusion with various common household materials. People frequently mistake clusters of white or grayish dust bunnies for these reproductive structures, but dust lacks the uniform, spherical shape of the individual eggs. Another common look-alike is white, fuzzy mold, which can grow on damp organic material in basements, but its soft, fibrous texture is distinctly different from the firmer structure of an egg or the silk of a sac.
The excrement of small insects, known as frass, can also be mistaken for eggs, but frass is typically dark and irregular in shape. Furthermore, the egg sacs of other small household spiders, such as the common house spider (Parasteatoda tepidariorum) or the false black widow (Steatoda triangulosa), are often misidentified. Steatoda egg sacs are typically perfect, cottony white or cream-colored spheres, while Parasteatoda sacs are more teardrop-shaped and papery. These are much more tightly woven than the loose, see-through silk bundle created by the Cellar Spider.