Complete House Bugs Identification Guide: 15 Common Indoor Insects

Identification: The most common indoor cockroach species in the United States, German cockroaches thrive in warm, humid kitchen environments and reproduce extremely rapidly.

Key Characteristics:

• Size: 1/2 to 5/8 inch long (13-16mm)
• Color: Light brown to tan with two dark parallel stripes behind the head
• Behavior: Nocturnal, scatter when lights turn on, prefer warm areas near appliances
• Signs: Fecal spots (small dark pepper-like specks), musty odor, egg capsules
• Where Found: Kitchen cabinets, under sinks, behind refrigerators, near dishwashers

Prevention: Eliminate food crumbs immediately, fix water leaks, seal cracks and crevices, store food in airtight containers, and take out garbage daily.

Identification: Named for the rotten coconut smell they emit when crushed, these tiny ants are the most frequent kitchen invaders in American homes.

Key Characteristics:

• Size: 1/16 to 1/8 inch long (2.4-3.2mm)
• Color: Dark brown to black
• Behavior: Form visible trails to food sources, attracted to sweet and greasy foods
• Colony Size: Can contain 100,000+ workers with multiple queens
• Where Found: Counter tops, near sugar/honey containers, around pet food bowls

Control Tip: Wipe down trails with vinegar solution, use ant baits near entry points, and seal cracks where they enter. Never spray ants with pesticides as this causes colonies to split and multiply.

Identification: These tiny flies appear seemingly from nowhere and can complete their entire life cycle in just one week, leading to rapid population explosions.

Key Characteristics:

• Size: 1/8 inch long (3mm)
• Color: Tan/light brown body with distinctive bright red eyes
• Behavior: Hover around fruit bowls, garbage cans, drains, and fermented beverages
• Reproduction: Females lay up to 500 eggs near fermenting organic matter
• Life Cycle: Egg to adult in 8-10 days at room temperature

Identification: The most destructive stored-product pest in homes, pantry moths infest grains, cereals, nuts, dried fruits, and pet food.

Key Characteristics:

• Size: 1/2 inch wingspan (8-10mm body length)
• Color: Distinctive two-tone wings - pale gray front portion, reddish-brown back portion
• Signs: Webbing in food packages, small white larvae, silken threads, adult moths flying at night
• Where Found: Pantry shelves, inside food packages, cupboard corners
• Damage: Contaminate food with larvae, feces, and silk webbing

Elimination: Discard all infested products, vacuum shelves thoroughly, wash containers with soap and water, store new food in airtight glass or plastic containers.

Identification: These ancient, wingless insects have existed for over 400 million years and are perfectly adapted to humid indoor environments.

Key Characteristics:

• Size: 1/2 to 3/4 inch long (12-19mm)
• Color: Silvery-blue to gray with metallic sheen, some brown varieties
• Body: Carrot-shaped with three long tail bristles, covered in scales
• Movement: Fast, fish-like wiggling motion, can run up to 15 inches per second
• Where Found: Bathtubs, sinks, shower stalls, under bathroom rugs, in grout

Damage Risk: Feed on book bindings, wallpaper paste, photographs, sugar, coffee, hair, and fabrics containing starch or cellulose.

Identification: Often mistaken for tiny moths, drain flies emerge from bathroom drains where their larvae feed on organic sludge buildup.

Key Characteristics:

• Size: 1/16 to 1/5 inch long (1.5-5mm)
• Color: Gray to black, fuzzy appearance
• Wings: Large, hairy wings held roof-like over body when at rest
• Behavior: Weak flyers, hop short distances, rest on walls near drains
• Breeding Sites: Sink drains, shower drains, floor drains, sewer lines

Elimination: Clean drains with mechanical brush or enzyme drain cleaner (not chemical cleaners). Pour boiling water down drains daily for one week, then use drain gel to prevent return.

Identification: While their appearance is alarming with 15 pairs of long legs, house centipedes are actually beneficial predators that eliminate other household pests.

Key Characteristics:

• Size: 1 to 1.5 inches long (body), up to 4 inches including legs
• Color: Grayish-yellow with three dark stripes down the back
• Legs: 15 pairs of extremely long, delicate legs with black and white banding
• Movement: Lightning-fast runners, can move up to 16 inches per second
• Where Found: Bathtubs, bathroom floors, damp basements, crawl spaces

Identification: Bed bugs are experiencing a global resurgence, with infestations increasing 500% in the US over the past decade. Early detection is critical for successful elimination.

Key Characteristics:

• Size: 1/4 inch long (4-5mm) - about the size of an apple seed
• Color: Reddish-brown, flat oval body (swells and turns dark red after feeding)
• Behavior: Nocturnal blood feeders, hide during day in cracks and crevices
• Signs: Small blood stains on sheets, dark fecal spots, shed exoskeletons, sweet musty odor
• Where Found: Mattress seams, box springs, headboards, bed frames, electrical outlets, picture frames

Identification: Often confused with bed bugs, carpet beetles are actually more common but cause property damage rather than bites. Their larvae feed on natural fibers.

Key Characteristics:

• Size: Adults 1/16 to 1/8 inch (2-3mm), larvae up to 1/4 inch (6mm)
• Color: Adults have mottled black, white, and brown/orange scales; larvae are tan with brown hair tufts
• Damage: Larvae eat wool, silk, leather, fur, feathers, and animal-based materials
• Signs: Irregular holes in fabrics, shed larval skins, fecal pellets
• Where Found: Closets, under beds, in carpets (especially edges), stored clothing

Prevention: Vacuum regularly including under furniture, dry-clean wool items before storage, store clothes in sealed plastic containers, and maintain low humidity.

Identification: While technically arachnids, house spiders are among the most frequently encountered creatures in bedrooms and deserve mention for identification purposes.

Key Characteristics:

• Size: 1/4 to 5/16 inch body (6-8mm), leg span up to 2 inches
• Color: Yellowish-brown with darker brown patterns
• Body: Two body segments, eight legs, no antennae
• Web: Build messy, tangled cobwebs in corners
• Where Found: Upper room corners, behind furniture, closets, under beds

Identification: Known for their distinctive chirping sound, house crickets invade homes in fall seeking warmth and moisture, particularly in basements.

Key Characteristics:

• Size: 3/4 to 7/8 inch long (16-22mm)
• Color: Light yellowish-brown with darker brown bands on head
• Features: Long antennae (longer than body), large hind legs for jumping
• Sound: Males produce loud chirping by rubbing wings together
• Where Found: Basements, crawl spaces, near water heaters, laundry rooms

Damage: Feed on fabrics (especially cotton and silk), paper products, and food crumbs. Can damage clothing and upholstery.

Identification: These worm-like creatures invade basements in large numbers during rainy periods or in fall, seeking moisture and shelter.

Key Characteristics:

• Size: 1 to 1.5 inches long (25-40mm)
• Color: Dark brown to black, sometimes with reddish tinges
• Body: Cylindrical, segmented, with two pairs of legs per segment
• Movement: Slow, wave-like motion; curl into a tight spiral when disturbed
• Where Found: Basement floors, near foundation walls, under stored items

Identification: Despite urban legends, earwigs don't crawl into ears. These nocturnal insects enter basements seeking dark, moist hiding places.

Key Characteristics:

• Size: 5/8 to 3/4 inch long (14-20mm)
• Color: Reddish-brown to dark brown
• Distinctive Feature: Forcep-like pincers (cerci) at rear of abdomen
• Behavior: Nocturnal scavengers, hide in crevices during day
• Where Found: Under cardboard boxes, in stored newspapers, basement corners

Prevention: Reduce moisture with dehumidifiers, seal foundation cracks, remove clutter and hiding places, and eliminate outdoor debris near foundation.

Identification: Despite the name, cat fleas infest both cats and dogs and are the primary flea species found in American homes, even in pet-free households.

Key Characteristics:

• Size: 1/16 to 1/8 inch long (1.5-3mm)
• Color: Dark reddish-brown, become darker after feeding
• Body: Laterally compressed (flat side-to-side), powerful hind legs for jumping
• Signs: "Flea dirt" (black specks that turn red when wet), pets scratching excessively
• Where Found: Pet bedding, carpets, upholstered furniture, baseboards

Identification: These overwintering flies invade homes in fall by the hundreds or thousands, clustering in attics, wall voids, and sunny rooms.

Key Characteristics:

• Size: 1/4 to 3/8 inch long (6-10mm) - larger than house flies
• Color: Dark gray to black with golden hairs on thorax
• Behavior: Sluggish flyers, cluster in large groups on sunny walls and windows
• Season: Enter homes in late fall, emerge in spring
• Where Found: Attics, wall voids, around windows, upper floors

Control: Seal exterior cracks before fall migration (August-September). Vacuum up indoor flies and seal entry points. Professional treatment of wall voids may be necessary for severe infestations.