Pillbug Control

Pillbugs are a very common sight in Oklahoma. This animal has taken on many different names over the years ranging from roly-poly to woodlouse. Though the pillbug is often called an insect, they are actually a terrestrial Isopod.

The pillbug belongs to the class Crustacea, making it closely related to the lobster, crab and shrimp. Crustaceans, however, are part of a larger group of joint-legged animals called Arthropoda. Arthropods all have a tough outer cuticle that is divided into flexible segments.

Pillbugs are characterized by their round-backed profile that can be rolled into a ball, similar to an armadillo, coining the name pillbug. The head of a pillbug is broad and contains two sharply-angled antennae. This land crustacean is also equipped with four pairs of mouthparts.

The seven trunk segments found on the pillbug all possess their own set of legs, resulting in seven distinct leg groups. Behind these segments is the pleon, which is divided again into six smaller segments. The pleon covers a pair of five pleopods, which in turn covers overlapping gills easily visible from the bottom of the animal.

The gills of a pillbug are responsible for many vital functions to sustain life. The primary functions include reproduction, gas exchange and excretion. Because of the unique anatomy of a pillbug, they do not urinate, and instead, pass it as a gas through their bodies.

Within the United States, there are 12 known species of pillbugs found within Northern and Central United States. Many more species can be found in coastal areas and in Floridian wetlands. Most pillbugs look nearly identical from a distance, however, with magnification many differences are clearly visible.

Pillbugs are not native to North America and were transplanted in the region from European countries. The earliest history of pillbugs within the Americas can be traced back to the 19th century through genetic testing. It is believed they arrived with traded lumber on the Mississippi River and St. Lawrence River lumber routes.

Habits

Pillbugs can be found in humid environments throughout the day. The largest populations of pillbugs can most often be found in compost piles and deposits of leaf litter. Many can also be found within piles of rocks, wood deposits and under fallen tree bark.

The pillbug is a nocturnal animal that will travel large distances during a period of the night. On evenings that are particularly humid, groups of pillbugs can easily be spotted feasting on dead vegetation and leaf litter. Pillbugs can be found in most gardens at any time of day, however, they will hide during periods of sunlight.

The diet of a pillbug consists of decaying plant and animal material. The most common food sources for a pillbug are algae, moss, fungi and bark. The pillbug will also eat feces from a variety of sources, including its own. As pillbugs defecate they lose copper precious to their livelihood, for this reason, they eat their own feces to retain copper content.

Large populations of pillbugs can draw in a number of unsavory pests within and around the home. Natural predators of the pillbug include amphibians and reptiles such as frogs and lizards. However, some spiders feed exclusively on pillbugs and will be more prevalent with increased populations of the animal.

Life Cycle

Pillbugs will reproduce in the months of May through September. The pillbug is capable of creating offspring through parthenogenesis, or reproduction without fertilization, but a male is typically involved in the process. Male pillbugs have elongated pleopods that they use for fertilization. Mating has seldom been witnessed, but a male pillbug will crawl across the females back to fertilize her eggs.

Once fertilization is successful, a female pillbug will develop a fluid-filled pouch to lay eggs into. Once the female has successfully fertilized her eggs, they will hatch within the passing of a few days. Each brood will contain up to a dozen young pillbugs.

Once the eggs hatch, juveniles will absorb the fluid in the pouch before breaking free. This process can take several hours. Upon exiting the pouch young pillbugs will only have six pairs of legs, and will develop the seventh pair following their first molt.

Juvenile pillbugs will remain in the pouch of a mother until they are fully formed. Often young pillbugs will take on a white color as seen with insects such as cockroaches. After molting, the color of a pillbug will begin to darken. Juvenile pillbugs are born with only six leg sets, but will grow their seventh pair after the first molt.

Pillbugs will continue molting every few weeks throughout the duration of their life. One unique difference in the molting of a pillbug is its ability to molt in two separate sections. The common species of pillbug in the United States has an average lifespan of two to three years.

Pillbugs in Oklahoma

In Oklahoma, the common pillbug, or Armadillidium Vulgare, is the most abundant species of pillbug. There are significant populations found throughout North America and many other countries. Though this species is native to the Mediterranean; it has been introduced to nearly every continent that contains a hospitable environment.

Common Pillbug

The common pillbug is a very active surface and soil dwelling terrestrial isopod. In order to survive, the common pillbug requires a humidity level within a range of 50% to 60%. Any conditions with a lower percentage of humidity will promote desiccation and kill the animal.

In most cases, the optimal habitat for a common pillbug will include large amounts of organic matter undergoing decomposition. Moderate temperatures with low direct sunlight will help the common pill bug flourish and retain humidity and moisture levels. Though some species of pill bug will nest near water sources throughout the winter, the common pillbug prefers a dry area that isn’t directly near water.

Finding a common pillbug is a relatively easy affair. Raising natural debris such as large stones or fallen logs will almost always net a large quantity of this land-dwelling crustacean. This particular species prefers large-particle soil as seen in flower beds or greenhouse applications.

The common pillbug can be identified from other terrestrial isopods because of its clearly visible antennae. These antennae are easily observed any time the common pillbug rolls itself into a defensive ball. This species is much hardier than other pillbug species because of a thicker cuticle that allows them to avoid dehydration more efficiently.

This species of pillbug exhibits a distinctly oval shape due to its elongated body. Juvenile common pillbugs can measure anywhere between 5 and 7 millimeters in length, while the adults are larger, spanning 10 to 15mm in length. Studies have shown that male and female common pillbugs have a nearly equal mass.

Pigments within the common pillbug give the isopod a dark coloration within their abdomen and distinct color spots within the dorsal. Typically, this species will have yellow shaded spots, but it is not uncommon to see brown or red. The overall color of a pillbug will open take on a dark gray primary color, but variants of color can exist.

The common pillbug has an average lifespan seemingly shorter than related species. In the wild, the average lifespan of a common pillbug can be as short as a year and a half, though some live for a few years. Studies have found that this species requires a high social activity to increase their potential life span. When placed in isolation and still receiving optimal environmental conditions, common pillbugs faced extremely high mortality rates.

Ecosystem Role

Pillbugs play a critical role in the decay of natural plant materials, making them an important piece in the decomposer fauna. Though they can do damage to some transplanted, young plants within a garden, pill bugs generally will focus on already dead and decaying matter. In a compost pile, pillbugs can speed up the process of decay naturally.

The pillbug returns organic matter into the soil after being consumed. In a cycle commonly associated with earthworms, the excrement of a pillbug is then digested by fungi, protozoa and bacteria. This, in turn, gives plants vital nutrients in the form of nitrates, phosphates and other nutrients to ensure proper growth.

Pillbugs are also capable of ingesting heavy metals from coal spoils or slag heaps that may be contaminating the soil. The metals they are capable of ingesting include copper, lead, zinc and cadmium. By removing these metals, pillbugs promote restoration by encouraging accelerated topsoil promotion.

Prevention

In most cases, pillbugs will only enter a home in mass when water sources are unavailable outside. Though the pillbug is not harmful to humans, their presence can be unwelcomed. To keep pillbugs from entering a home, there are several steps that can be taken to ensure maximum protection.

Minimize Moisture

Pillbugs require moisture in order to survive. When excess moisture is found near a home’s foundation, the likelihood of a pillbug infestation is increased. It is important to not allow water to pool near a home’s foundation or a crawlspace. To fix this issue, divert water away from the home through the use of gutters, downspouts and splash blocks.

Repair Leaks

Leaking faucets and water pipes can create an environmental suitable for the pillbug. Air conditioning units can also create condensation that will make moisture levels higher than normal. By remedying these issues, homeowners will make it less likely for pillbugs to enter a home.

Remove Debris

Food sources for pillbugs are typically found outside. The pillbug will generally eat vegetable and plant debris or decaying matter. Removing leaf piles, grass clippings, unnecessary mulch and stones near the foundation of a home will make the likelihood of an infestation less severe.

Seal Cracks

Most often pillbugs will enter a home through small cracks predominately from sliding doors that serve as an exit from the home. By installing tight fitting weather stripping or door sweeps this problem can be remedied in most cases, though sometimes caulk may also be necessary. Pillbugs may also enter the home through cracks in foundation walls or basement windows. Sealing these entry points will make pillbugs less likely to enter.

Diatomaceous Earth

Diatomaceous Earth is a sedimentary deposit composed of the fossilized remains of diatoms. This natural bug killer can be very effective against isopods such as the pillbug because they require so much moisture. When a pillbug crawls over diatomaceous earth, the soft underbelly will become damaged and cause dehydration and eventual death.

Common Associations

Pillbugs are often confused with another land crustacean, the sowbug. The major difference between these two woodlouse species is the sowbugs inability to roll up when disturbed. The sowbug also has two appendages not seen with pillbugs that resemble tails.