Spider beetles are a type of beetle that may resemble spiders, owing to their superficial similarities in appearance. These beetles, found across the United States, are known to infest stored products and can be a common household nuisance, though not as well-known as other pests^[1^].
Although spider beetles resemble spiders and might give some people the creeps, their potential for harm is a topic of interest. Understanding these pests and whether they can bite you can help put your mind at ease and assist in dealing with infestations if necessary.
Spider Beetles Overview
Appearance
Spider beetles are small insects, generally measuring between two to five mm in length. They have an oval or cylindrical shape, long legs, and are usually brown in color. Their appearance has a superficial resemblance to spiders, which is the origin of their common name1.
Species
There are several species of spider beetles found in the U.S. that infest stored products1. They belong to the family Ptinidae and are not considered true spiders or arachnids, but insects.
Habitat
These beetles are common and widespread but not as abundant nor well known as other household pests1. They are found in various habitats, including homes, where they can infest stored food products and cause damage.
Diet
Spider beetles primarily feed on a variety of stored foods and organic materials such as grains, fruits, and even dead insects. Their diet is primarily plant-based, and they do not bite humans or other animals.
Biting Potential
Comparing to Other Insects
While spider beetles resemble spiders in appearance, they differ significantly in their biting habits. For example, unlike spiders, which can bite and inject venom into their victims, spider beetles lack the necessary mouthparts or venomous glands to do so. On the other hand, insects such as mosquitoes rely on their elongated proboscis to pierce the skin and extract blood.
Spider Beetles vs Other Insects
- Spider beetles: Do not bite
- Spiders: Possess venomous bites
- Mosquitoes: Use proboscis for blood extraction
Spider Beetles and Humans
Fortunately for humans, spider beetles pose minimal threat. Rather than biting, these creatures employ their long legs to navigate the environment and seek food sources, often in crevices or dark spaces where they can go undetected. This is in contrast to insects like bedbugs, which typically bite at night, leaving itchy and painful bumps on the skin.
To avoid scratching bug bites or spider bites, applying ice to the area can soothe itchiness and prevent further irritation. The key takeaway is that spider beetle bites are virtually nonexistent, making them far less dangerous to humans than other insects.
Spider Beetle Characteristics
- Appearance: Resemble spiders
- Legs: Long, used for navigation
- Biting potential: Virtually nonexistent
Infestations and Prevention
Signs of Infestation
Spider beetles (Mezium americanum) are common pests infesting food products, especially cereals, grains, seeds, and beans, as well as dead insects and rodent droppings. In homes, they are typically found in pantries. Some indications of infestation include:
- Small, brown, long-legged beetles in food products or around pantries
- Packaging with holes or tears, caused by beetle feeding
- Silk webbings and frass (insect droppings) around infested areas
Preventive Measures
Preventing spider beetle infestations involves a few simple steps:
- Store food products in well-sealed containers made of glass or thick plastic
- Regularly inspect pantries for signs of infestation
- Maintain low moisture and humidity levels in storage areas
- Keep homes clean and free from rodents and other potential food sources
- Seal cracks and crevices where beetles may enter or hide
When comparing to other pests, spider beetles are more attracted to moisture and less to the warmth of a habitat. So, controlling moisture can be quite effective.
Pest Control
If an infestation occurs, there are several methods to control spider beetles:
- Vacuum clean infested areas to remove beetles, their food sources, and habitat
- Discard contaminated food products
- Use pest control treatments, such as insecticides, pheromone traps, or heat treatments (in severe cases)
- Consult pest control professionals, if necessary
Here’s a comparison table to show the pros and cons of some control methods:
| Control Method | Pros | Cons |
|---|---|---|
| Vacuuming | Non-chemical, easy-to-use | May not eliminate all beetles |
| Insecticides | Effective, can target specific areas | Chemical exposure risk, may harm non-target organisms |
| Pheromone Traps | Non-toxic, can monitor beetle activity | Not effective for large infestations |
| Heat Treatments | Chemical-free, effective | Requires professional assistance, can be costly |
Remember, the most effective strategy is prevention and early detection. Maintaining clean pantries, good storage practices, and low moisture levels can help avoid spider beetle infestations.
Impact on Homes and Food Storage
Potential Damage to Food
Spider beetles are not as well-known as other household pests, but they can still cause damage to stored food products1. Their attraction to a variety of food sources makes them a potential threat to different items in your pantry. For example, they are known to infest:
- Dried fruits
- Spices
- Wheat
- Books (made of old wood)
- Cacao
- Figs
- Almonds
- Rye bread
- Ginger
- Paprika
They prefer moist areas and can easily hitch a ride into your home by infesting food packages or hiding in walls2. Spider beetles can even infest pet food if it’s left unsealed.
How to Protect Your Pantry
To avoid potential damage caused by spider beetles, there are several steps you can follow to protect your pantry and food storage. Some of these methods are:
- Store food in airtight containers or sealed plastic bags3.
- Keep your pantry clean and dry, as moisture encourages pantry pests4.
- Regularly check food sources for signs of infestation.
- Dispose of any infested food products immediately.
| Methods | Pros | Cons |
|---|---|---|
| Airtight containers | Seals out any pests, keeps food fresh | Need to invest in containers, takes space |
| Sealed plastic bags | Affordable, easy to find | Disposables, potential environmental waste |
| Regular check-ups | Prevents large infestations | Time-consuming, need to be vigilant |
| Cleaning & disposing | Maintains clean pantry | Wasted food, continuous effort required |
Making an effort to keep your pantry clean and free of plausible hiding spots for spider beetles will significantly reduce their chance of infesting your food sources and pantry.
Interesting Spider Beetle Facts
Spider beetles are small insects that resemble spiders, hence their name. These beetles infest stored products and are found in a variety of environments, such as mills and warehouses. Common types include the American spider beetle, the smooth spider beetle, and the whitemarked spider beetle.
These beetles are nocturnal creatures, coming out at night to feed. They have long legs and, in some cases, wings which help them crawl and fly in search of food. Spider beetles go through various stages, starting from eggs, then to larvae, and ultimately to adult beetles, which can be male or female.
Although spider beetles can be a nuisance, especially in food-storage areas, they are generally not harmful to humans. They do not transmit diseases.
To control spider beetle infestations, cleaning and vacuuming areas where they are found is usually effective. Maintaining clean and closed food storage areas is essential in preventing infestations. In extreme cases, professional pest control services may be required.
Characteristics of common spider beetle types:
-
American spider beetle
- Brown to reddish-brown in color
- Hairy body and long, flexible antennae
- 2-4 mm in size
-
Smooth spider beetle
- Shiny, reddish-brown appearance
- Wings present
- Oval-shaped body
- 2-5 mm in size
-
Whitemarked spider beetle
- White scales on dark brown body
- No wings
- Cylindrical body
- 3-4 mm in size
In conclusion, spider beetles may look like ticks or spiders, but these insects are neither harmful nor disease-carrying. However, they can be a nuisance, requiring vigilance and proper sanitation measures to keep them away from food-storage areas.
Footnotes
Reader Emails
Over the years, our website, whatsthatbug.com has received hundreds of letters and some interesting images asking us about these insects. Scroll down to have a look at some of them.
Letter 1 – Spider Beetle
Subject: What’s this bug?
Location: NYC, Manhattan
April 10, 2016 9:28 am
Hi Bugman –
I stumbled upon your website when I decided to do a little detective work to identify a bug I have encountered several times in my apartment.
I live in NYC, in a high rise on the 35th floor. I have found this type of bug more than once in my bathtub. It has a rounded body, though it looks sort of oblong in the photo. It’s very small – smaller than an adult bedbug, and quite fast, so the pictures are not as clear as they could be.
I though it could be a juvenile cockroach but I have seen those and they are quite a bit flatter. This bug has a substantial, rounded backside. It’s abdomen resembles that of a black widow spider but this is clearly not a spider. Any thoughts?
So curious! Your help will be appreciated.
Signature: Tommy G
Dear Tommy,
This is a Spider Beetle in the subfamily Ptininae. Though your images lack critical detail, we believe this is a Smooth Spider Beetle, Gibbium aequinoctiale, and according to BugGuide, they are found in “Mainly houses, flour mills, occasionally warehouses, hospitals, stores” where they feed upon a “wide variety of dead organic materials; may be a dry stored product pest.” You should check the pantry for the site of the infestation.
Letter 2 – Spider Beetle
Subject: Can you identify this bug?
Location: Washington DC
August 3, 2014 4:53 pm
Hi, we live in washington DC and have found this bug in our home. It’s mostly near the baseboards and on the carpet but we’ve also found them in the bathroom, in the kitchen, and two on our bed. They are pretty small close to the size of a pin. We haven’t received any bites.
Signature: Rebecca
Hi Rebecca,
Spider Beetles in the subfamily Ptininae infest stored foods. See BugGuide for additional information.
Letter 3 – Spider Beetle
Subject: What is this bug?
Location: Queens, NY
August 16, 2014 6:34 am
I have found 3 similar bugs within a week. The first two were crawling on my bathroom floor and the third was on the couch. They crawl pretty fast and from what I can tell they have 6 legs. When killed, they make a popping sound (there is no blood inside). Color is reddish black.
I live in NY and these were found this month (August).
Signature: Alex
Dear Alex,
Spider Beetles like the one in your image frequently infest stored foods, including large, bargain bags of pet food. Check items in your pantry to locate the source of the infestation.
Letter 4 – Spider Beetle
Subject: What’s this??
Location: Kansas City MIssouri
January 2, 2017 5:25 am
What is this?! I live in Kansas City MO! I found this bug on my carpet floor and I’ve done tons of research on google images but I still can’t find out what this is! It’s small with a hard round back! Help!
Signature: However!
The Spider Beetle is a common household pest that will infest stored foods in the pantry.
Letter 5 – Spider Beetle
Small red bug
Location: Silver Spring, MD
December 1, 2010 11:03 pm
Hello, thank you for helping me identify this guy. It is the second one I have found. I live in Maryland near DC in an apartment building. I the first one crawling across my wooden floor at a slow pace. This is the second one (found in my kitchen in a large bowl I don’t use).
I saw the first one in May and this one just last week (Late November). I brought it into work and took pictures under the microscope since it is only about 2-3 mm.
Upon first seeing it I thought it was some sort of spider, but then realized it only has 6 legs.
Signature: Thank you for your help!
Spider Beetles like the one in your photograph are one of the numerous species of beetles that will infest stored food. You should clean out the pantry.
Letter 6 – Spider Beetle
Strange House Tick?
Location: Chicago, IL
March 17, 2011 7:10 pm
Dear Bugman/Bugwoman,
We were living in a damp, dark basement apartment and started seeing these strange bugs about a month ago. We probably found 3 or 4 and then we moved to a new apartment a week ago and they seem to have followed us. We’ve already found 3 of them crawling around on our stuff. I’m feeling paranoid that we’re infested with something! Is there any way you can help me identify our unwelcome stowaway? I have attached 2 pictures. They aren’t the clearest, but maybe they will be enough. If you need another picture I can send some. I captured a couple of the bugs so I could try to figure out what they were.
Thanks for your help.
Sincerely,
Signature: Ed
Hi Ed,
There are many small beetles that infest stored foods, and many of them have a cosmopolitan distribution. This is a Spider Beetle, most likely in the genus Mezium as your photo, though blurry, appears to show a pronotum with furry pubescence which according to BugGuide is a distinguishing feature.
Letter 7 – Spider Beetle
Subject: trying to identify an insect…
Location: New York, NY
October 2, 2012 3:31 pm
Hi there. I found this insect in my bathroom in Manhattan. I haven’t been able to identify it from various sources online. I don’t think that it is a tick, but am really curious. Do you have an idea of what it might be? Thanks.
Signature: James
Hi James,
This is a Spider Beetle. They infest stored foods in the pantry.
Letter 8 – Spider Beetle
Subject: Help
Location: New York
December 3, 2013 11:17 am
Hey, I found this strange looking bug that I cant seem to find online. I found it in my linen closet and where I put cooking utensils. I saw it at work also, in a container of cotton balls. I never found them alive, always dead. Please help! Thank You
Signature: Ashley J
Hi Ashley,
This is a Spider Beetle, a common household pest that infests stored foods.
Letter 9 – Spider Beetle
Subject: Need a second opinion on this bug!
Location: NYC
December 16, 2016 7:39 am
I sent these photos to an exterminator, and he told me it’s a spider. But it looks to me like the bug has 6 legs and 2 antennae! Hoping it’s not a bedbug!
Signature: AKR
Dear AKR,
Commonly called a Spider Beetle, this is a common household pest that infests stored foods.
I live in queens, ny and found a few of these bugs in my apartment. I’ve lived in the city for almost 10 years and this is the first time I came across these bugs. I found one on my dresser and in my closet…twice hiding under my laundry bag. Yuck!
i recently came across this in my brooklyn NY apt….this was in my bathtub, very tiny, .. but mine are slow, (maybe because the tub was cold ?).. i see them only once and awhile.
they are very tiny, …. i dont see pinchers, like the pseudoscorpion, ..