Article author: Extension Entomologist at Weslaco (Vacant)
Most recently reviewed by: Sonja Swiger & Pat Porter (2020)

Common Name(s): Daddy longlegs, Harvestmen, Opiliones

Description

Opilionids, also called harvestmen or daddy longlegs, are common arachnids that are often under-appreciated, or even greatly feared.  While it is true that they are related to spiders, they are in a separate Order, or taxonomic group, from spiders.  There are some key differences between these two groups, listed in Table 1.  Opilionids lack venom glands and fangs, thus the urban legend that they produce a deadly venom, just cannot bite is completely inaccurate.

Table 1.  Differences between opiliones and spiders.

Opiliones	Spiders
Do NOT produce venom	Produce venom
Do NOT produce silk	Produce silk
2 eyes	6-8 eyes

Like other arachnids, opilionids have two-segmented bodies although there is no narrowing where these two segments join.  Thus, their bodies are oval in shape, ranging in length from approximately 0.2 – 1 cm.  They have four pairs of legs that may be very long and spindly, or much shorter.  They also have a pair of pedipalps near their mouth they use for capturing food, feeding, and mating.  They typically blend in well with their environment and may be reddish brown to grey or black in color with various markings on the legs and body.

Origin and Distribution

There are over 6,000 species of Opiliones identified worldwide and they can be found on all continents except Antarctica.  Many species can be found throughout Texas, and several species are quite common in residential landscapes.

Habitat & Hosts

Most species are active at night and remain sheltered under bark, mulch, rocks, and in caves or other structures during the day.  They dehydrate easily thus are often found in association with moist environments. Occasionally, they can be found in large aggregations, probably to take advantage of a favorable habitat, reduce water loss, for protection from predators, or to mate.

They do not have good vision but rely largely on vibrations detected by specialized hairs on the second set of legs along with olfactory cues to navigate their environment and locate prey.  Opilionids are generalist predators and/or scavengers, feeding on a wide range of live and dead soft-bodied prey including aphids, caterpillars, beetle larvae, slugs, mites, spiders, and even other opilionids.  Unlike spiders that use venom to subdue prey, harvestmen grab prey and use their mouthparts (chelicerae and pedipalps) to tear apart and consume food.  Some species have also been reported to feed on pollen, plant matter, and fungi.

Opilionids may deter predators by releasing repelling or irritating chemical compounds in the form of a gas or fluid.  They may also exhibit a “bobbing” behavior, vibrating their bodies rapidly, making it difficult for a predator to get a good grip on them.  If a predator does latch onto a leg, opilionids are capable of releasing individual legs at the joint closest to their bodies.  This detached leg may continue to twitch for some time, distracting the would-be predator while they escape.

Life Cycle

Most opilionids reproduce sexually, although a few are capable of reproducing parthenogenetically (females produce offspring without mating).  After mating, males often guard the female until she deposits her eggs. Females have a long ovipositor they use to place eggs singly or in groups in protected areas such as under mulch, bark, or in the soil.  In some species the females may remain to guard the eggs until they hatch, while many others provide no further maternal care.  Eggs hatch in about a month and the young will go through several molts before they reach the adult, sexually mature, stage.  Adults may live from just a few months to a year or more.  In more northern regions of Texas, they may overwinter in all life stages in protected areas such as outbuildings, under rocks, logs, etc.

Management

If you live in the State of Texas, contact your local county agent or entomologist for management information. If you live outside of Texas, contact your local extension for management options.

Opilionids are not considered a pest.  Contrary to the popular urban legend, they are not one of the most venomous and deadly organisms known to mankind!  They lack venom glands and fangs, making this myth completely unfounded. Therefore, if one is found in a dwelling it can safely be removed outdoors.  Opilionids feed on many pest insects such as aphids and caterpillars, and “clean up” by feeding on dead organisms, so they can be considered beneficial in the landscape.  However, if they become a nuisance or aggregate in significant numbers, habitat modification, including removing shady or protected areas, and drying out or exposing favorable habitats to sunlight will likely cause them to relocate.

Related Publications

Ohio’s Natural Enemies: Harvestmen (also known as daddy longlegs). Ohio State University. Available here.

Daddy Longlegs (Harvestmen). Missouri Department of Conservation. Available here.

Citations

Gardiner, M. and M. Griffith. Ohio’s Natural Enemies: Harvestmen (also known as daddy longlegs). 2016. Ohio State University Extension. Ent-68. Available here.

Pinto-da-Rocha, R., M. Glauco and G. Gonzalo. 2007. Harvestmen: The Biology of Opiliones. Harvard University Press. Boston, Massachusetts. 608 pages.