Water Mite

Arrenurus genus

Bio Images UK / Malcom Storey

Bio Images UK / Malcom Storey

Like all mites, Water Mites are close relatives of spiders. Like spiders, they have eight legs and soft bodies.

There are many different kinds of mites. Some live in soil, some on plants. Water Mites live in marshes, ponds, and lakes. They like shallow, still water with lots of plants.

There are many different species of Water Mites; this page focuses on the ones in the Arrenurus genus. Arrenurus mites grow up to three millimeters long and are usually brown or greenish. Males are bigger than females.

Arrenurus mites stay near the bottom. They can swim or crawl to get where they'r going, but when they relax, they sink back to the bottom.

Arrenurus mites are only active when there's daylight.

NatureWatch

NatureWatch

Water Mites have an interesting life cycle. After mating in late Spring or early Summer, female mites lay eggs on stones or plants in the water. Eggs are red, and one female lays up to 400 at one time. Eggs hatch in one to six weeks, depending on the species and temperature.

Mite larvae hatch with only 6 legs. Right away they swim around looking for an aquatic insect. Water Mite larvae are parasites, and they need a host to live on. Some insects chosen to be hosts include dragonfly naiads, damselfly naiads, fly larvae (including mosquitoes), true bugs, and stone fly nymphs. One insect may carry around up to 20 mite larvae.

Water Mite larvae munch on their host while it carries them. When a mite larva has grown enough, its exoskeleton (outer shell) becomes bag-like. The larvae stays inside the bag and changes to a nymph. As it changes, the "bag" stays attached to the host.

When the nymph is ready, it leaves the host. The nymph has eight legs and looks a lot more like an adult Water Mite.

Water Mite nymphs eat the same foods adults do, including small insects, aquatic worms, and other mites (even their own kind). Nymphs continue to eat and grow, until they are ready to go into their fourth stage (egg, larvae, and nymph are the first three stages).

Each nymph finds some algae, an aquatic plant, or another object to attach to. The nymph shrinks inside another "bag" for about a week while it changes to an adult.

Predators of adult Water Mites include aquatic insects, crustaceans (such as water fleas and scuds), hydras, and small fish.

In the larva stage, when attached to its host, the mite may have a problem if the host leaves the water. If this happens, the mite can pop out of its bag, or hold on, hoping its host returns to the water. If the host doesn't return, or the larva drops off on land, it dies.

Bio Images UK / Malcom Storey

Relationships in Nature:

PREY
PREDATORS
SHELTER
OTHER

Aquatic Worm

Green Hydra

Yellow Pond Lily

Ebony Jewelwing H

Green Darner

Ebony Jewelwing

Tussock Sedge

Green Darner H

Ebony Jewelwing

Green Darner

Pickerelweed

Asian Tiger Mosquito H

Common Whitetail

Large Diving Beetle

Common Duckweed

Crane Fly H

Asian Tiger Mosquito

Eastern Dobsonfly

Common Cattail

CommonWater Strider H

Crane Fly

Copepod

Buttonbush

Fragile Forktail H

Water Mite

Crayfish

Arrow Arum

CommonWater Strider

Creek Chub

Common Reed

Flatworm

Eastern Mosquitofish

Long-leaf Pondweed

Greater Bladderwort

Lizard's Tail

Predatory Nematode

Marsh Bulrush

Fragile Forktail

Green Algae

Hydrilla

Skunk Cabbage

Swamp Rose Mallow

Greater Bladderwort

Wild Rice

Relationship to Humans:

Arrenurus mites, and other Water Mites, are helpful since they control insect populations (including mosquitoes). They are also food for other helpful animals, such as hydras and fish.

SCIENTIFIC CLASSIFICATION

KINGDOM
Animal
PHYLUM
Arthropod
CLASS
Arachnid
ORDER
Acarina
FAMILY
Arrenuridae
GENUS
Arrenurus
SPECIES
Arrenurus (many species)

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