The black "bugs" that curl up into a ball when disturbed are most commonly pill bugs, often referred to as roly polies. Despite their common name, these fascinating creatures are not insects but rather terrestrial crustaceans, related to shrimp and lobsters.
Identifying Pill Bugs (Roly Polies)
Pill bugs are easily recognized by several distinct characteristics:
- Appearance: They have a segmented, oval-shaped body, typically dark gray to black, though some may appear brownish. They possess seven pairs of legs and two pairs of antennae.
- Size: Most pill bugs are small, usually growing up to about 1/2 inch (1.3 cm) in length.
- Defining Behavior: Their most notable trait is their ability to roll into a tight, protective sphere when they feel threatened or are simply touched. This behavior is where they get the nickname "roly poly."
Are They True Bugs?
It's a common misconception that pill bugs are insects. In reality, they are a type of isopod, belonging to the subphylum Crustacea. This classification means they are more closely related to marine crustaceans like crabs and lobsters than to insects like beetles or ants. They breathe through gills, which is why they require moist environments to survive.
Where to Find Them and Why They Curl
Pill bugs thrive in damp, dark environments and are often found in gardens, yards, and sometimes indoors if conditions are suitable.
Preferred Habitats
- Outdoors: They are frequently found under rocks, logs, leaf litter, decaying wood, compost piles, and potted plants. Their need for moisture means they are rarely seen in dry, open areas during the day.
- Indoors: If they venture inside, it's usually into damp areas like basements, crawl spaces, garages, or laundry rooms, especially if there are leaks or excessive humidity.
The Curling Defense
The act of curling into a ball, known as conglobation, serves multiple purposes for pill bugs:
- Predator Defense: This is their primary defense mechanism against predators such as spiders, birds, and centipedes. By rolling into a hard sphere, they protect their vulnerable undersides and appear less appetizing.
- Moisture Conservation: Curling up also helps them conserve moisture in slightly drier conditions, reducing the surface area exposed to evaporation.
Environmental Role and Management
Pill bugs play a beneficial role in the ecosystem as decomposers. They feed on decaying organic matter, breaking it down and returning nutrients to the soil, which improves soil health.
| Feature | Pill Bug (Roly Poly) | Sowbug (Woodlouse) |
|---|---|---|
| Curling Ability | Curls into a perfect ball | Cannot curl completely into a ball |
| Tail Appendages | None visible | Two distinct tail-like appendages |
| Common Name | Roly Poly | Woodlouse |
| Classification | Terrestrial Isopod (Crustacean) | Terrestrial Isopod (Crustacean) |
While generally harmless, large populations can sometimes become a nuisance, especially if they enter homes.
Managing Pill Bugs
If pill bugs become problematic, focus on reducing moisture and eliminating their preferred habitats:
- Reduce Moisture:
- Repair leaky pipes and faucets.
- Improve drainage around the foundation of your home.
- Use dehumidifiers in damp basements and crawl spaces.
- Ensure proper ventilation in areas prone to humidity.
- Remove Harborage:
- Clear away leaf litter, woodpiles, stones, and other debris near the foundation.
- Trim dense vegetation to allow for better air circulation and sunlight penetration.
- Seal Entry Points:
- Seal cracks in foundations, around windows, and under doors to prevent indoor entry.
- Ensure screens on windows and doors are intact.
For more information on pill bugs and their management, you can consult resources from university extension programs, such as the University of California Integrated Pest Management Program.
