NPIPM:Opiliones
Authors: Ashley Mueller, Buyung Hadi
Spiders are arachnids, and they are the primary arachnid in many habitats. They have eight legs and two body sections, the cephalothorax and the abdomen, which are separated by the waist. When young spiders hatch, they look like tiny adult spiders. As they grow, they molt to accommodate their developing bodies.
Spiders are beneficial because they are predators of problematic insects. Although their natural habitat is outdoors, they can make their way indoors in search of prey. Most spiders have special glands that allow them to produce and manipulate silk, so they are able to capture prey. They also have poison glands in their mandibles, allowing them to kill their prey. Generally, spiders are not able to pierce human skin with a bite, but if they are able to, the venom is harmless in most cases.
Identification
Harvestmen belong to the class Arachnida, the same class as spiders, scorpions, and mites. However, harvestmen are not true spiders. They have a single body segment, whereas spiders have two. They also lack the venom glands and spinnerets found in spiders. Harvestmen have eight legs, fang-like mouthparts, and pedipalps (feelers) near the mouth, and they lack antennae. Female harvestmen tend to have larger bodies and shorter legs than males.
Habitat
Harvestmen prefer moist, shady environments, and they can often be found in caves, shade of wood or plant growth, and basements where there is little light. Some harvestmen species search the ground and plants carefully for dead or slow moving insects, insect eggs, earthworms, and decaying plant material for food.
Life Cycle and Seasonal History
Female harvestmen lay eggs by the hundreds into moist soil in the fall. When young harvestmen hatch in the spring, they look like tiny adults. As they develop into adults, the young harvestmen molt to accommodate their growing bodies. Adult harvestmen live for about one year. They are often seen in high numbers in the fall, around harvest time, as their name suggests.
Human Interaction and Urban Impact
Harvestmen are not cause for medical or economic concern. They do not damage buildings or structures if they are found clustering indoors. They are considered beneficial insects because they feed upon multiple pests. Contrary to popular beliefs, harvestmen are not the most venomous spider on the planet: they are not venomous, and they are not spiders. If handled, they may emit a pungent odor as a defense against most predators.
Prevention and Management Approaches
To prevent harvestmen from entering homes and buildings, seal the foundation, inspect any window or door screens for holes, reduce clutter from around the foundation, and reduce any potential food sources for harvestmen to keep them from entering or growing high numbers within the facility. Remove clutter which can serve as a hiding spot for spiders.
If harvestmen activity is observed indoors, remove them from the building and place outdoors or simply vacuum. Pesticides are not recommended because harvestmen are beneficial, and each harvestman would require direct application of the pesticide.
Other Online Resources
For information regarding labels of chemical control options, please visit NPIC MAPL
