Early signs before you see a live roach
Droppings that look like ground pepper or coffee grounds
Where to look: Along baseboards, inside cabinet hinges, under the refrigerator, behind the stove
A musty, oily smell
Where to look: Strong in enclosed spaces — under sinks, inside lower cabinets, behind appliances
Egg casings (oothecae)
Where to look: Dark brown, oval, about 8mm long — tucked in cabinet corners, between book spines, in cardboard
Smear marks
Where to look: Brown irregular streaks along walls and floor junctions where cockroaches travel regularly
Shed skins
Where to look: Translucent brown husks near harborage areas — cockroaches molt 5–8 times before adulthood
Why spray-and-pray doesn't work
Over-the-counter aerosols and roach bombs (foggers) are effective at killing exposed cockroaches but actively make infestations harder to treat:
- Foggers push roaches deeper into wall voids and behind appliances
- Repellent sprays create treated zones that cockroaches route around
- Surviving roaches scatter to new harborage areas, spreading the population
- Repeated exposure without elimination allows resistance to develop
What professional treatment targets
Effective cockroach treatment uses non-repellent materials and gel baits placed directly in harborage areas — not surface sprays. Cockroaches carry bait back to the colony, and secondary kill occurs when others feed on contaminated feces and cadavers. A professional also identifies the species — German cockroaches (the most common indoor species) require different treatment placements than American or Oriental cockroaches.
Most infestations require a follow-up visit 2–3 weeks after the initial treatment to assess reduction and address any remaining harborage areas.
Health risks worth knowing
Cockroach allergens — shed skin, feces, and saliva — are a documented trigger for asthma and allergic rhinitis, particularly in children. The CDC identifies cockroach allergens as one of the most significant indoor asthma triggers in urban housing. Getting the infestation under control isn't just about comfort.
See the full details on our cockroach and flea control service page for Columbia, MD homeowners.