I was bitten by a spider, I think, in my bed a couple of nights ago and the bite has blistered and is oozing and hurts. I think it must have been a brown recluse spider because it looks like a photo of a bite I found online. How common are they in New Hampshire?

S. W., Concord, NH

Not very common at all. In fact, brown recluse spiders do not occur in New Hampshire or in any states nearby (see Brown Recluse Spiders Do Not Occur in the Northeast: Q&A). The range of the brown recluse spider covers a few states in the south central and lower Midwestern U.S. That’s not to say that a brown recluse or two couldn’t end up in a residence elsewhere under unusual circumstances, say if someone moving from Oklahoma packed a few boxes that also contained brown recluse spiders. The spiders don’t establish in our region, however, even if they are carried here.

PROBABLY NOT A SPIDER BITE AT ALL

The chances of the spider that bit you being a brown recluse are virtually nil. In fact, the chances that the bite was even from a spider are remote (see Got a Bite? Don’t Blame it on a Spider). Most of the bites that people, including doctors, attribute to spiders are not from spiders at all. One survey found that 80% of suspected spider bites were actually from insects or other arthropods, or were not even bites but instead were from a medical or skin condition. Often when people are bitten outside by mosquitoes or flies or chiggers, the bite doesn’t make itself known until several hours later when the victim is at home. And there are other indoor insects that could be biting you such as fleas or bed bugs.

Spiders are convenient scapegoats, especially when the bite or the itching is first noticed in the morning. Many of us have this sneaking suspicion that spiders hide in or around our beds and crawl over us in our sleep. Actually, about the only way that a spider in your bed would bite you is if you rolled over on it or smashed it somehow in your sleep. Spiders are shy and not aggressive and not commonly found in beds. Even in regions where the brown recluse occurs and even in homes that have the spiders present, bites almost never happen.

INSECT AND SPIDER BITES ARE HIGHLY VARIABLE

As for the appearance of the bite, there is usually no reliable way to differentiate one spider bite from another, or a spider bite from a bed bug or other insect’s bite, or even an insect bite from a skin condition. All can result in a red, swollen area that can burn or itch, or ooze — to greater or lesser degrees. People that are sensitive to bites or stings from certain spiders or insects are going to have a stronger, and probably different, reaction than other individuals.

The only way to confirm that you were bitten by a brown recluse spider is to capture the spider and have it positively identified by a specialist. It has been estimated that 60% of alleged brown recluse spider bites occur in areas of the U.S. where brown recluse spiders do not even exist. That should tell you that most of us tend to sensationalize the situation.

But if you do have spiders in your home, or if you think bed bugs or other pests may be biting you, give Colonial Pest a call and have our experts conduct an inspection. For a one-time bite, there is very little chance that it was from a brown recluse spider if you live in the Northeast.

For more, see Spiders in New Hampshire.