OHIO STATE UNIVERSITY EXTENSION
AGRICULTURE AND NATURAL RESOURCES FACT SHEET
ENT-68-15
Ohio’s Natural Enemies: Harvestmen
Also known as daddy longlegs
Mary Gardiner, Department of Entomology, and Mary Griffith, Ohio State University Extension
Overview
Harvestmen are arachnids in the order Opiliones. The scientific name of this group comes from the Latin word opilo,
which roughly translates to shepherd. At one time European shepherds used stilts to look over their sheep, and it is
thought that the look of this arachnid’s body atop its long legs inspired the comparison. Harvestmen are referred to by
many common names including shepherd’s spiders, harvest spiders, reapers, and here in the United States where our
fauna is dominated by long-legged species, daddy longlegs.
Role in Biological Control
Harvestmen are beneficial predators in the garden and very common in residential landscapes. They can be found
on the soil surface, and under rocks or mulch. They are also commonly found on structures, tree trunks or climbing
garden vegetation. While the presence of harvestmen is not likely to completely suppress pest populations, they do
contribute to biological control. Harvestmen are very susceptible to dehydration, thus providing garden elements
such as rocks, mulch and logs to provide shelter from heat and direct sunlight is important to promoting harvestmen.
Growing a diversity of flowering plants to support bloom throughout the growing season will provide protein in the
form of pollen, which may be an important resource at times of low prey availability. Also, avoiding the use of broad
spectrum insecticides is advised.
Identification
Spiders
Harvestmen
6–8 eyes
2 eyes
Produce silk
Do not produce silk
Produce venom
Do not produce venom
Indirect mating
Direct mating
Like all arachnids, harvestmen have a two-segmented
body consisting of a prosoma and an opisthosoma. In harvestmen these body segments do not narrow where they
join, giving the appearance of an oval, single-segmented
body that ranges in length from 2 to 10 mm. They have
four pairs of long, slender legs and one pair of pedipalps
on their prosoma, which are short appendages near their
chelicerae or mouthparts that are used in prey capture,
feeding and mating. They are cryptically colored and
blend in well with surroundings.
Photo courtesy of MaLisa Spring
Harvestmen are arachnids and look a lot like spiders, but they have some important differences. Harvestmen have
fewer eyes, do not make webs and do not produce venom. The urban legend about harvestmen producing the most
deadly venom but lacking the ability to bite a human is simply not true!
Harvestmen are related to spiders—both are in the class
Arachnida. Yet there are some important differences among
these creatures, including their eyes. Harvestmen have an
ocularium, which is a raised area centered on their prosoma that
contains two eyes, whereas spiders have 6–8 eyes.
extension.osu.edu
agnr.osu.edu
Ohio’s Natural Enemies: Harvestmen—page 2
Chelicerae
Pepipalp
Opisthosoma
Prosoma
Patella
Ocularium
Eye
Femur
Illustrations by Rachel Shoop
Trochanter
Coxa
Claw
Tibia
Metatarsus
Photo courtesy of MaLisa Spring
Photo courtesy of MaLisa Spring
Tarsus
Phalagium opilio is found commonly in garden beds. This
individual may have been feeding on pollen. Growing a wide
variety of flowering plants in your landscape will provide natural enemies with a diversity of prey as well as nectar and pollen
resources.
Life Cycle
Most harvestmen mate to reproduce but a few species
are parthenogenic, meaning that the females can produce
offspring in the absence of males. After mating, females
utilize their long ovipositors to deposit eggs singly or in
groups in protected cavities under tree bark, soil or mulch.
In some species, females guard eggs until they hatch.
Harvestmen will hatch from their eggs and molt though
several immature stages before reaching adulthood. The
length of the adult stage varies from 1 to 2 months to a
year or more. In temperate climates, harvestmen can
overwinter as eggs, immatures or adults in protected sites.
Photo courtesy of John Maxwell
Several species of harvestmen are found in Ohio gardens. Phalagium opilio (Phalangiidae), and species in the
genus Leiobunum (Sclerosomatidae) are common in Ohio
residential landscapes.
Harvestmen use their second pair of legs to acquire vibrational
cues from possible nearby prey or potential predators. This
Leiobunum individual has its second pair of legs outstretched to
survey the environment.
Harvestmen mate directly, unlike spiders where sperm is transferred indirectly via a pedipalp to the female. As part of their
courtship some male harvestmen produce a “nuptial gift”— a
source of food produced from his chelicerae that the female
consumes during mating. After mating the male will guard his
mate until she lays eggs.
Ohio’s Natural Enemies: Harvestmen—page 3
References
Beccaloni, J. 2009. Arachnids. University of California Press. Berkeley,
California. 230 pages.
Gardiner, M.M. 2015. Good Garden Bugs. Quarry Books. Beverly,
Massachusetts. 176 pages.
Pinto-da-Rocha, R., M. Glauco and G. Gonzalo. 2007. Harvestmen: The
Biology of Opiliones. Harvard University Press. Boston, Massachusetts.
608 pages.
Harvestmen consume many types of pest
insects. This individual is feeding on an invasive
brown marmorated stink bug (Halyomorpha
halys).
Photo courtesy of Bryan E. Reynolds
Harvestmen are able to distinguish varying intensities of light with their
two eyes, but they rely mostly on other cues to navigate their environment and search for prey. Their second pair of legs contains sensory
hairs that can detect vibrations and possibly olfactory cues from prey
within their vicinity. Unlike spiders who inject venom into their prey, harvestmen simply grasp it with their chelicerae and pedipalps and tear it
apart to consume it. Harvestmen are known to consume both dead and
live soft-bodied prey. They are generalist predators who feed on many
arthropod groups that include pest species such as aphids, psyllids,
grasshoppers, beetle larvae, slugs, mites and caterpillars. As generalists, they will also capture and consume other beneficial arthropods
including lady beetle eggs, spiders and other harvestmen. They are
also known to occasionally steal prey captured by another individual!
Some harvestmen have also been reported to feed on pollen. These
arachnids are very susceptible to dehydration, and sources of water
are important for their survival and longevity. Most species are active
at night and seek shelter from the sun during the day.
Harvestmen exhibit some interesting defensive behaviors. If threatened by a predator such as a bird, some harvestmen species initiate
a defense called bobbing. They vibrate their body rapidly, which may
make it difficult for the predator to grasp them. If a predator grasps the
leg of a harvestmen they can detach it at the joint between their femur
and trochanter. The detached leg will twitch for up to an hour distracting
the predator. Unfortunately though, the detached leg segments do not
regenerate. Harvestmen also possess chemical defenses. If disturbed
they release a defensive compound from scent glands located on
their prosoma. The compound can be released as a liquid or gas that
encompasses the arachnid’s body. Some species will also collect the
defensive liquid from their scent gland and use their leg to smear it onto
a would-be attacker. Chemistry of the compound varies among species.
Although harvestmen are generally found on their own, some species do form aggregations at times. Some aggregations may include
hundreds of individuals. Aggregating may aid in their defense against
predators, reduce water loss and/or improve mating success.
Photo courtesy of Ted Kropiewnicki
Feeding and Habits
Safety in numbers? Aggregating may increase
the effectiveness of the bobbing behavior or
chemical defenses harvestmen employ to ward
off potential predators.
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