HOUMA, La. - A breed of poisonous invasive spiders are on the march across Louisiana and have already been sighted in Terrebonne and Lafourche parishes, according to local Louisiana State University AgCenter officials.
Generally found in tropical areas, the brown widow spider is closely related to the black widow spider.
Widow spider venom is a powerful neurotoxin. Its bite may not initially be noticed but will soon become very painful.
Symptoms of a widow bite include headache, tiredness, excessive sweating, nausea, shortness of breath, muscle cramps and rigidness in the abdomen and legs.
Elderly residents, children and people with compromised immune systems are more at-risk from a brown widow bite.
Symptoms of a brown widow bite tend to be more localized to the bite site. Study has shown that the venom of a brown widow may be much stronger than a black widow, but the brown widow is less likely to inject a large amount of venom.
Very few of the 3,500 species of spiders found in North America have bites that are considered dangerous to humans, according to the New Orleans Mosquito Control Board. Most are too small and produce a venom that is too weak to harm people.
Historically there have only been two species of spider in Louisiana that were dangerous to humans, the brown recluse and the black widow.
But in recent years, the brown widow spider has begun popping up in south Louisiana.
The brown widow is a tropical spider whose populations were historically limited to Florida within the United States.
Michael Massimi, an invasive species expert with the Barataria-Terrebonne National Estuary Program, said that mild winters in recent years may have helped their spread.
Kyle Moppert, medical entymologist with the state Department of Health and Hospitals, said sightings of the spider began to increase in the New Orleans area after Hurricane Katrina in 2005. The LSU AgCenter sent out warnings to residents about increases in the spiders' population in the state in 2007.
Barton Joffrion, an agent with the LSU AgCenter, said local residents have been reporting sightings of the brown widow for the last decade.
The spiders were likely brought in through interstate shipping or transportation, Joffrion added.
The spider ranges in color from gray or tan to dark brown and may reach 1 inch to 1½ inches long. Like its better-known black widow cousin, the brown widow spider has an orange hourglass marking on its belly.
Its body is often brightly colored, Moppert said, with patterns on the top of the abdomen in brown, white, black and orange and often has dark bands on its legs.
The spider weaves loose webbing and its distinctive eggs look like white balls with spikes.
The spiders are shy and are unlikely to bite unless provoked, Moppert said.
The brown widow spider is most often found in areas that haven't been disturbed, such as brush piles, wood piles and areas where debris has accumulated. They also can show up in crawl spaces, under chairs and flower pots, eaves and porch railings.
“They like to nest in windows and in the handles of trash cans,” Moppert said. “Their bite is as bad as a black widow, but they will jump and run away because they're shy.”
The best way to avoid an encounter with the spiders is to remove areas where they may nest, Massimi said. Pick up clutter and seal cracks and crevices around windows.
“Clutter is a big attraction,” Massimi said. “They would probably love a messy old shed.”
If bitten by what you think is a brown widow spider, you should seek medical attention immediately. To help medical responders, if possible you should safely trap the spider that bit you for identification.
Nikki Buskey can be reached at 857-2205 or firstname.lastname@example.org.