While spiders are common in Maryland, severe bites are infrequent, and most species pose no significant threat to human health. Some spiders can deliver a medically significant bite, but these instances are rare and occur when a spider feels threatened or is disturbed. Understanding which spiders warrant attention is important.
Key Spiders to Know
Maryland is home to the black widow spider (Latrodectus mactans), recognized for its potent venom. The female is shiny black with a distinctive red hourglass marking on her abdomen. Black widows are found in undisturbed, dark, and sheltered outdoor areas like woodpiles, sheds, garages, and under eaves. They are not aggressive and bite only when their web is disturbed or they are accidentally pressed against skin.
The brown recluse spider (Loxosceles reclusa) is another species associated with medically significant bites, though its presence in Maryland is not native and extremely rare. It is light to dark brown with a violin-shaped marking on its back, the “neck” pointing towards the rear. Reclusive, they prefer dark, undisturbed indoor spaces like attics, basements, closets, and stored items, or outdoors under rocks and logs. Sightings in Maryland are attributed to spiders being inadvertently transported into the state.
Understanding Bite Symptoms
A black widow bite may initially feel like a pinprick or go unnoticed, but pain develops within an hour. Localized pain around the bite site intensifies and spreads to the abdomen, back, or chest, accompanied by muscle cramping, stiffness, nausea, vomiting, and sweating. These neurotoxic symptoms last for several days, with severe symptoms improving within two to three days. Children and older individuals may experience more serious reactions.
Brown recluse bites cause minimal or no pain at first, with symptoms developing several hours later. The bite area may become reddened and swollen, forming a blister. A distinguishing feature is the development of a pale center surrounded by a red ring, which progresses to a dark blue or purple color within 12 to 24 hours, indicating tissue damage or necrosis. This necrotic wound can expand into an open sore and may take weeks or months to heal, requiring medical intervention.
If You Are Bitten
If you suspect a spider bite, especially from a black widow or brown recluse, take immediate action. Clean the bite area gently with mild soap and water to prevent infection. Apply a cool compress or ice pack for 10 to 20 minutes to reduce pain and swelling. Elevate the bitten limb, if possible, to minimize swelling.
Seek professional medical attention if symptoms are severe, worsen, or if you suspect a bite from a black widow or brown recluse. Look for signs like severe pain, muscle cramps, difficulty breathing, spreading redness, or a growing wound. Medical professionals provide appropriate treatment, which may include pain relief, muscle relaxants, or in rare cases, antivenom for black widow bites. If safe, capturing the spider or taking a clear photo assists medical staff with identification.
Reducing Your Risk
Minimize spider encounters around your home and yard. Seal cracks and gaps in foundations, windows, and doors to block entry points. Ensure window and door screens are in good repair to keep spiders outside. Reducing clutter in basements, attics, and garages removes ideal hiding spots.
When working outdoors, especially in woodpiles, gardens, or storage sheds, wear gloves, long-sleeved shirts, and long pants. Before putting on shoes or clothing stored in undisturbed areas, shake them out to dislodge spiders. Maintain a tidy yard by trimming overgrown vegetation away from the house and removing debris piles like leaves or logs to reduce spider habitats.