Harvestman The Biology Of Opiliones Poisonous

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Including Daddy-Long-Legs
Critter Files/Harvestmen
By Blake Newton
University of Kentucky, Department of Entomology

  1. Comparing a Spider to a Harvestmen is like comparing a blue whale to a chimpanzee. Spiders are a different order (Araneae) than Harvestmen (Opiliones), and although both Arachnids, they diverged millions of years ago. Opiliones are more closely related to Scorpions, Pseudoscorpions, and Solifugids than they are to the Araneae.
  2. Harvestmen covers virtually every aspect of harvestman biology.Inevitably, the longest chapter is on taxonomy, dealing with the disturbing features of the families and subfamilies in the four major This is the first major revision of the order in over fifty years, and it is a tour de force.This is a book that will be prized by many naturalists, both amateur and professional.
  3. Associative learning has been demonstrated in many species of invertebrates, but has not been studied in arachnids, except for some spiders and a whip-spider. Herein, we tested the ability of a Neotropical harvestman, Discocyrtus invalidus (Arachnida, Opiliones) to associate a shelter with a chemical stimulus. We used an arena with a white light at the top and two openings on the floor, one giving access to a dark shelter and the other one closed with a mesh.
Common Kentucky Harvestmen:

Harvestman The Biology Of Opiliones Poisonous Animals

Harvestmen are not dangerous to humans. None of the described species has poison glands. They are not 'true' spiders even though they look like spiders in many ways. For example, harvestmen have no venom or silk glands; spiders have these.


KINGDOM: Animalia PHYLUM: Arthropoda CLASS: Arachnida ORDER: Opiliones (harvestmen)

Other Names: daddy-long-legs, opilionids, shepherd spiders, granddaddy-long-legs, reapers


Harvestmen are members of the class Arachnida, which also includes spiders, scorpions, and mites. Like all arachnids, harvestmen have 4 pairs of legs, fang-like mouthparts called 'chelicerae,' and 2 antennae-like appendages near the mouth called 'pedipalps.' They have no antennae. Most Kentucky harvestmen have very long legs, and these species are usually called 'daddy-long-legs.' Some harvestmen have short legs and look very similar to mites, but these species are rarely seen in Kentucky.

Harvestmen are often confused with spiders, but harvestmen are not true spiders. Spiders have 2 body segments (cephalothorax and abdomen) that are distinct and separated. On harvestmen the 2 body segments appear fused into a single large body segment (as with mites and ticks). Also, spiders have venomous fangs, whereas the fangs of harvestmen have no venom glands.

SIZE: Body length up to about 1/4' for Kentucky harvestmen

Like all arachnids, harvestmen have incomplete metamorphosis. This means that young harvestmen hatch from eggs and look like tiny versions of the adults. They molt (shed their skin) as they grow larger. Most harvestmen in Kentucky live for about a year. Females lay eggs by the hundreds in moist soil.


The biology and ecology of harvestmen is poorly known. Most harvestmen species are found in moist, shady environments. Some harvestmen live deep in caves, while others are found in basements or in the deep shade of woods or plant growth. Regardless of where they live, they are usually active in darkness or in the shade. Some harvestmen search methodically over the ground and on plants for slow-moving or dead insects, insect eggs, earthworms, and decaying plant material. Harvestmen are often seen sitting motionless on the upper sides of leaves, like the one shown below, perhaps waiting in ambush for soft-bodied insect prey.

Harvestman on leaves (B. Newton 2003)

Although they resemble spiders, harvestmen do not have venomous fangs or silk glands. Some species, however, have glands on the sides of their bodies that can secrete bad-tasting and bad-smelling defensive chemicals which help protect them from predators. Harvestmen are sometimes eaten by birds, large spiders, and predatory insects like assassin bugs.


Harvestmen are often found with bright red mites attached to their bodies. These mites are the immature stages of species belonging to the family Erythraeidae. They are believed to be parasitic. Among many mite species, the immature stages are parasitic while the adults are predatory. A 'parasitic' organism is one that attaches itself to and feeds on a host, like a tick on a human.

Mites on harvestman leg
(B. Newton 2003)
Mites are common parasites on all kinds of arthropods, including many insect and spider species. Click here to read a brief summary of a scientific study concerning mites and daddy-long-legs.
Harvestmen are sometimes a nuisance around buildings where they congregate by the dozens, but they are not harmful to humans, animals, buildings, or crops.

DADDY-LONG-LEGS: Leiobunum genus
FAMILY: Leiobunidae Genus: Leiobunum

As mentioned above, long-legged harvestmen species are usually called 'Daddy-Long-Legs.' Many of the daddy-long-legs encountered in Kentucky are in the genus Leiobunum. Leiobunum daddy-long-legs are almost always present around trees, shrubs, or any thick vegetation in Kentucky during warm months. They are also common around buildings, especially barns, sheds, and similar structures. Pictured below are two common Leiobunum species. The one on the left is probably Leiobunum vittatum, a species that occurs over much of the eastern United States.

Daddy-long-legs, Leiobunum sp. (R. Bessin 2000)

During warm months, harvestmen are extremely common on the shady sides of buildings, underneath eaves, in crawl spaces, and on trees, and they are found in both rural and urban environments. Harvestmen can be easily collected by hand, but take care not to break off any legs. Harvestmen will usually stay still for a photo as long as you don't touch them. These creatures have soft bodies, and should be preserved in alcohol.


The legs of harvestmen fall off easily and continue to twitch for some time after removal. It is believed that this helps the daddy-long-legs escape predators (as when a lizard's tail breaks off).


You may have heard that 'daddy-long-legs are the most poisonous spiders in the world, but their fangs are too small to bite humans.' This is a widespread myth. It has even been presented as a fact on televised nature programs. Daddy-long-legs are not actually spiders, and they do not have venom glands. For details about this myth, take a look at this webpage from the University of California Entomology Department.

In the old days, it was believed that you could use daddy-long-legs to find your lost cattle. When you wanted to know which direction the herd had wandered to, you could pick up a daddy-long-legs by all of the legs but one, and the free leg would point in the direction of the cattle (or so it was believed).

Another myth from the old days: if you kill a daddy-long-legs, it will rain the next day.

Original document: 25 May 2004
Last updated: 19 Oct 2006
Harvestman the biology of opiliones poisonous to cats

The Kentucky Critter Files are maintained by Blake Newton, Department of Entomology, University of Kentucky.
Contact: [email protected]

Anatomy of Phalangium cornutum. d, Sheath of penis. e, penis. f, glans.

The penis of the Opiliones (harvestmen) is an intromittent organ that is not present in other arachnids. It consists of a long shaft (the truncus) and a terminal capsule called a glans, containing a stylus and ejaculatory duct. It may have from one to three muscles, or none as in the specialized lineage Grassatores, where the penis is operated by haemolymph pressure. In some members of the Cyphophthalmi, the structure has been termed a 'spermatopositor'.[1]

Harvestman The Biology Of Opiliones Poisonous Animal

This denomination refers to a superficial similarity (analogy) with vertebratepenises and does not have any phylogenetic relationship with it.


  1. ^Ricardo Pinto-da-Rocha, Glauco Machado, Gonzalo Giribet (eds). (2006). 'Morphology and Functional Anatomy'. Harvestmen: the Biology of Opiliones. Cambridge, MA: Harvard University Press. pp. 59–60. ISBN0674023439.CS1 maint: Uses authors parameter (link)

External links[edit]

Harvestman The Biology Of Opiliones Poisonous To Cats

  • Opiliones reproductive anatomy- Dr. Jefferey Schultz, University of Maryland
  • Harvestman Spider penis, Thelbunus mirabilus - Australian Museum

Harvestman The Biology Of Opiliones Poisonous Species

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