Flat Bugs

Flat Bugs is a general common name often used to refer to two distinct groups of insects, both characterized by their extremely flattened body shape:

**Aradidae (Flat Bugs):** True bugs found under the bark of trees, feeding on fungi.
**Cimicidae (Bed Bugs):** The notorious parasitic bugs that feed on human and animal blood.

For the purpose of common pest control discussion, this entry will focus on the **Aradidae family**, which are often encountered in homes after being accidentally carried in with firewood or lumber. They are harmless decomposers and fungivores, not structural or blood-feeding pests.

Taxonomy and Classification

Flat Bugs (Aradidae) belong to the order Hemiptera (true bugs), suborder Heteroptera. They undergo incomplete metamorphosis (egg, nymph, adult). There are over 2,000 species worldwide. Their flattened shape is an adaptation for living and moving within the narrow space between the bark and the wood of trees.

Origin of the Name "Aradidae"
The family name "Aradidae" traces its roots back to the 19th century, when it was formally described by the entomologist Maximilian Spinola in 1837. The name itself is derived from the type genus Aradus. This genus name likely references the insects’ characteristic habitat—nestled flat underneath bark, often hidden in tight spaces—though the exact etymology is somewhat obscure (as is common with many scientific names established in that era). Over time, "Aradidae" has remained the accepted scientific name, distinguishing these cryptic, pancake-like bugs from their less-flattened relatives.

Local Subfamilies and Genera

Within our region, Flat Bugs (family Aradidae) are represented by several distinct subfamilies and genera. Here’s a breakdown of what you’re likely to encounter:

Aneurinae: Includes genera such as Aneurus and Iralunelus.
Aradinae: Contains Aradus and Quilnus.
Calisiinae: Known locally by the genus Calisius.
Carventinae: Features genera like Acaricoris and Neoproxius.
Mezirinae: This diverse group includes Aphleboderrhis, Brachyrhynchus (four documented species), Mezira, Nannium, Neuroctenus, and Notapictinus.

Not all of these genera are equally common, but all play their part in decomposing fungi beneath bark. Some may not yet be fully detailed in local guides, so don’t be surprised if you stumble across a mystery species during your next firewood run!

Physical Description

Adult Flat Bugs are 1/4 to 1/2 inch long and possess a unique appearance:

**Body Shape:** Exceedingly flat, wide, and oval or rectangular.
**Coloration:** Typically dull brown, gray, or black, often blending in perfectly with bark.
**Texture:** Their bodies and heads are often highly textured, appearing rugged or bumpy.
**Mouthparts:** Possess sucking mouthparts (stylets) housed in a beak, used for fungal or plant feeding.

Distribution and Habitat

Flat Bugs are found globally, particularly in forested regions. Their primary habitat is under the loose or decaying bark of dead or dying trees, where they feed on fungal mycelium and decaying wood products. They are often inadvertently brought indoors during the winter via firewood or structural lumber, where they sometimes emerge seeking light and warmth.

Behavior and Damage

Aradidae are **ecological decomposers** and are entirely harmless to structural wood, furnishings, pets, and humans. They are not known to bite or carry diseases.

**Feeding:** They feed exclusively on the mycelia of certain fungi that grow on decaying wood, playing a role in the initial decomposition of fallen timber.
**Nuisance Factor:** Their conflict with humans is purely an aesthetic **nuisance**. When brought indoors with firewood, they may emerge from the wood when heated and crawl around the living space, causing concern due to their unusual appearance.

Management and Prevention

Control is focused on exclusion and interception of infested material. Chemical treatments are unnecessary.

**Firewood Management (Key Prevention):** Store firewood outdoors and away from the house foundation. Only bring in small quantities of wood that will be burned immediately. Brush or shake the wood vigorously outdoors before carrying it inside.
**Indoor Removal:** Any Flat Bugs found indoors can be easily removed by vacuuming or sweeping them up. They will not reproduce indoors or infest structural wood.
**Sealing Entry Points:** Ensure screens and exterior doors are sealed, as they may occasionally enter from outdoor populations.

Conservation and Research

Aradidae are managed as minor nuisance pests. Research often focuses on their evolutionary relationships and their ecological role in nutrient cycling within forest ecosystems.