[photo, Brown spider, Baltimore, Maryland]
  • Common Maryland Spiders (DNR)
  • Deer & Wood Ticks (University of Maryland Extension)
  • Arachnids (class Arachnida) are joint-legged invertebrates with eight legs. They include harvestmen (also known as "Daddy long-legs"), mites, scorpions, spiders, and ticks.

    Brown spider, Baltimore, Maryland, July 2014. Photo by Sarah A. Hanks.

    Mites. Members of the subclass Acarina, mites have a small head and a much larger body. Generally they have eight legs, though a few species and the juveniles may have fewer. They are very small, with some nearly microscopic. On the underside of leaves or within the plant, they lay their eggs. Some, such as the Clover Mite, however, also can lay eggs in sidewalk cracks. Depending on the species, mites can be either highly beneficial or very destructive to crops.
    [photo, Common House Spider, Baltimore, Maryland] Spiders. Unlike other arachnids, spiders have segmented bodies and four pairs of eyes. Spiders are predatory, using their pincers to hold their prey and then injecting it with venom. While many spiders in Maryland are venomous, most pose little danger to humans and will only bite in self-defense. Others, such as the Black Widow Spider and the Brown Recluse, pose a greater health risk and any bite must be treated immediately. Controlling insect populations in and around houses, gardens, and crops, spiders are highly beneficial.

    Common House Spider, Baltimore, Maryland, August 2015. Photo by Sarah A. Hanks.

    Ticks. Like mites, ticks belong to the subclass Acarina and have a small head with a larger body. They belong to either the "hard tick" group or the "soft tick" group, and feed on the blood of mammals, birds, reptiles, and amphibians. A hypostome on their head keeps them attached to their host. With their bites, ticks can transmit diseases, including Lyme disease and Rocky Mountain Spotted Fever, and must be removed promptly, but carefully, in order to avoid infection. Their populations can be controlled through good yard maintenance, including keeping grass short, trimming bushes, fencing deer out, and removing debris and cover for rodents. Regular grooming and inspection of pets, along with medicine from the vet, can reduce potential tick infestations inside the house.


    A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

    Harvestman (Family: Phalangiidae)
    Harvestmen get their name from the rake-like appearance of their extremely long and thin legs, which can be up to twenty times the size of their body. They have a small, spherical body and two eyes. They eat insects and carrion. Also known as Daddy Longlegs.

    Mite, Broad (Family: Tarsonemidae)
    Broad mites are translucent or brown in color. The males have claws on their back legs. Injecting a toxin into plants, they damage both food and ornamental crops, including fruit trees, coffee plants, violets, and begonias. They can be controlled with high temperatures or miticides.

    Mite, Bulb (Rhyzoglyphus)
    Bulb mites are yellow-white in color with brown mouths and legs. They feed on bulb crops, including garlic, amaryllis, hyacinth, and crocus. They can be controlled with predatory mites, cool temperatures, or miticides.

    Mite, Clover (Bryobia praetiosa)
    Clover mites are red or green with long front legs. While they feed on outside plants, they often are seen inside houses. They can be controlled by vacuuming or with external insecticides.

    Mite, Cyclamen (Family: Tarsonemidae)
    Cyclamen mites are translucent or brown in color and have a "waxy" appearance. The males have claws on their back legs. Cyclamen mites feed on buds and recent plant growth. They damage ornamental plants, especially begonias. With high heat levels or miticides, they can be controlled.

    Mite, Dust (Dermatophagoides spp.)
    Dust mites are translucent. They feed on organic matter, such as flakes of skin. Found in houses (especially in mattresses, carpets, & furniture), dust mites are a common cause of allergies and even asthma. They can be controlled by using high-efficiency particulate air (HEPA) filters, plastic covers on pillows and mattresses, high heat (as found in dryers), and thorough vacuuming.

    Mite, Phytoseiid [Predatory] (Phytoseiulus persimilis) (Family: Phytoseiidae)
    Predatory mites are pear-shaped, shiny, white to red-orange in color with long legs. They are very common in greenhouses where they are used to control problematic mite populations. With a voracious appetite, they can eat many Spider mites in a day.

    Mite, Spider (Family: Tetranychidae)
    Spider mites can be red to yellow with black spots, as seen on the Two-Spotted Spider Mite, or gray-brown like the Spruce Spider Mite. By draining the chlorophyll from the leaves, they damage plants. They can be controlled with predatory mites, thorough washings, or miticides.

    [photo, Black and Yellow Orb-Weaver Spider (Argiope aurantia), Glen Burnie, Maryland] Spider, Black & Yellow Garden (Argiope aurantia) (Family: Araneidae)
    Black and Yellow Garden spiders are Orb-Weavers. Black and Yellow Garden spiders have black legs with red or yellow bands and can grow up to two inches in length. They build (& rebuild) their webs, sometimes two-feet across, in sunny areas in and around gardens or fields. Also known as Corn Spider, Writing Spider, and Zipper Spider.

    Black & Yellow Orb-Weaver Spider (Argiope aurantia), Glen Burnie, Maryland, August 2014. Photo by Diane F. Evartt.

    Spider, Black Widow (Latrodectus mactans) (Family: Theridiidae)
    Black Widows are Cobweb spiders, which make tangled, stringy webs. Females are shiny black with the red "hourglass" pattern on abdomen, while males have red and spots on their abdomen. Generally, they stay in their web, often made in undisturbed areas of buildings. They have a venomous bite, which initially feels like a pinprick, but then pain develops around the affected area, followed by cramping. Sweating, nausea, and vomiting may occur. Medical attention is necessary if bitten by a Black Widow.

    Spider, Brown Recluse (Loxosceles reclusa)
    Brown Recluses have three pairs of eyes, light legs, and are about a half-inch in length. They have a dark violin-shaped mark on their head. They build webs in isolated locations, such as woodpiles, though they can be found in and around houses. Generally, they feed on insects. The Brown Recluse is an invasive species. Also known as Fiddleback Spider. Medical attention is necessary if bitten by a Brown Recluse.

    [photo, Cellar Spider (Pholcus phalangioides), Baltimore, Maryland] Spider, Cellar (Pholcus phalangioides) (Family: Pholcidae)
    Cellar spiders are pale yellow-brown and have very long, skinny legs with small bodies. Their loose, stringy webs are found in the corners of houses, usually in undisturbed spaces, and are used to catch small flying insects; however, if food is scarce, the cellar spider will tap another spider's web to draw it out and then eat it. Cellar spiders are common in and around houses, but do not bite people.

    Cellar Spider (Pholcus phalangioides), Baltimore, Maryland, July 2014. Photo by Sarah A. Hanks.

    Spider, Common House (Parasteatoda tepidariorum) (Family: Theridiidae)
    Common House spiders are Cobweb spiders, which make tangled, stringy webs. Females are gray or tan, while males are redder in color. These spiders are very common inside houses and their webs are usually in corners, around windows, or in the basement.

    Spider, Crab (Family: Thomisidae)
    Crab spiders have large front legs that are held out to the sides, giving them the appearance of crabs. Their colors generally match their surroundings. They use camouflage, not webs, to catch their prey. Crab spiders are useful to have in gardens as they eat insects that damage flowers and plants.

    Spider, Fishing (Dolomedes tenebrosus) (Family: Pisauridae)
    Fishing spiders are brownish-gray in color and are about an inch in length. Their legs are very long with black and brown bands. Generally, they live near water and can catch small fish, insects, or tadpoles. The Dark Fishing Spider (Dolomedes tenebrosus Hentz) can live further from the water, in woods or even houses.

    [photo, Funnel Weaver Spider (Agelenidae) in its funnel web, Baltimore, Maryland] Spider, Funnel Weaver (Family: Agelenidae)
    Funnel Weavers are brownish-yellow in color with dark longitudinal bands, about an inch in length, and have three rows of eyes. They make funnel-like webs on the ground, which they rarely leave. When its prey crosses the web, the Funnel Weaver will jump out and catch it. Also known as Grass Spider.

    Funnel Weaver Spider (Agelenidae) in its funnel web, Baltimore, Maryland, September 2014. Photo by Sarah A. Hanks.

    [photo, Jumping Spider, Baltimore, Maryland] Spider, Jumping (Family: Salticidae)
    Jumping spiders are brightly colored, with a large pair of eyes on the front of its face, in addition to its other three sets of smaller eyes. The males dance and vibrate in order to attract a mate. They get their name because they jump or run after their prey. Jumping Spiders do not build webs, but use their silk as a tether when jumping on prey. They are often found in or near buildings.

    Jumping Spider (Salticidae), Baltimore, Maryland, May 2015. Photo by Sarah A. Hanks.

    [photo, Longlegged Sac Spider, Baltimore, Maryland] Spider, Longlegged Sac (Chirocanthium mildei)
    Longlegged Sac spiders are yellow-green, have a dark stripe on their abdomens, and are a quarter-inch in length. They make their sacs, which are used for cover, in confined areas, often in the corners of ceilings and walls. They do not build webs, but instead hunt their prey, usually small insects. The Longlegged Sac Spider is an invasive species. Also known as Yellow Sac Spider. Longlegged Sac spiders are known to bite and medical attention is recommended if bitten.

    Longlegged Sac Spider (Chirocanthium mildei), Baltimore, Maryland, May 2015. Photo by Sarah A. Hanks.

    Spider, Marbled Orb Weaver (Araneus marmoreus) (Family: Araneidae)
    Marbled Orb Weaver spiders make circular webs between upright structures. Marbled Orb Weaver spiders have abdomens that become yellow (sometimes orange) with a black-marbled pattern as they mature. They make their webs in and around trees or other wooded areas. They tend to hide among leaves until their prey is caught on their web.

    Spider, Nursery Web (Pisaurina spp.) (Family: Pisauridae)
    Nursery Web spiders are large, hairy, about an inch long, and have a dark stripe running from their eyes down their back. They carry their egg sac in their mouth before placing it in the "nursery tent" for hatching. Nursery Web spiders are found in fields or wooded areas, but also within houses.

    [photo, Orb-weaver Spider (Neoscona crucifera), Baltimore, Maryland] Spider, Orb-weaver (Neoscona crucifera) (Family: Araneidae)
    Orb-weaver Spiders are generally brown or brown-red with darker marks on the abdomen and alternating dark and light bands on their legs. In length, females can grow to three-quarters of an inch, while males may reach a half-inch long. They often are found in the center of their webs, which can be up to two feet across and attached to buildings or between trees. Usually nocturnal, Orb-weaver Spiders will hide in daylight, but in the Fall, females may remain in their webs during the day. Also known as Barn Spider, Hentzís Orbweaver, and Spotted Orbweaver.

    Orb-weaver Spider (Neoscona crucifera), Baltimore, Maryland, September 2015. Photo by Sarah A. Hanks.

    [photo, Spined Micrathena Spider, Baltimore, Maryland] Spider, Spined Micrathena (Micrathena gracilis) (Family: Araneidae)
    Spined Micrathena Spiders are Orb-Weavers, which make circular webs between upright structures. Their spiky abdomens can be white, yellow, or brown-black. They are between a quarter- and a half-inch long. Between trees or shrubs, they build their webs, usually at face level.

    Spined Micrathena Spider (Micrathena gracilis), Baltimore, Maryland, September 2015. Photo by Sarah A. Hanks.

    Spider, Wolf (Family: Lycosidae)
    Wolf spiders are brownish-gray, about an inch in length, nocturnal, and have eyes that are reflective. The female will carry the egg sac, then hatchlings, on her back until they can hunt for themselves. They build tunnels in the soil or under stones or wood. They do not make webs, but instead chase their prey.

    Tick, American Dog (Dermacentor variabilis)
    American Dog ticks are flat, brown or red with white or silver markings on their back. The female is about .19 of an inch in length before feeding, but can nearly quadruple in size afterwards. They are most active from mid-Spring to late Summer. American Dog ticks prefer outside environments, especially wooded areas or long grass. Dogs are their primary host, but they will attach to people. Known carrier of the Rocky Mountain Spotted Fever, Tick Paralysis, and Tularemia. Also known as Wood Tick.

    Tick, Brown Dog (Rhipicephalus sanguineus)
    Brown Dog ticks are similar to American Dog ticks. They are red-brown with a long body, between .25 and .50 of an inch in length before feeding. Brown Dog ticks prefer to be indoors and can spend their entire lives inside houses or other structures. Dogs are their primary host, but they also will attach to people. Known carrier of Tick Paralysis.

    Tick, Deer (Ixodes scapularis)
    Male Deer ticks are dark brown, borderline black, while females are brown with orange-red on the back half of their body and black dorsal markings. They are just over .06 of an inch in length but will expand dramatically after feeding. The White-tailed deer and white-footed mouse are their primary hosts, but they also will attach to people. From late Summer to mid-Fall, they are the most active. They tend to be in wooded areas and along forest trails, but will appear wherever white-tailed deer are found. Known carrier of Lyme disease and Tick Paralysis. Also known as Blacklegged Tick.

    Tick, Lone Star (Amblyomma americanum)
    Lone Star ticks are brown. The females have a white spot on the back, while the males have scattered spots. Females are about are about .12 of an inch in length, but can nearly quadruple in size after feeding. They live in dark wooded areas and cannot survive indoors. White-tailed deer are their primary host, but they also will attach to people. Known carrier of Rocky Mountain Spotted Fever, Tick Paralysis, and Tularemia.

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