Household pests

Termites vs flying ants is the identification that costs people the most money. The EPA gives the distinguishing features: on a termite the "wings are roughly equal in length" and the "antennae are straight; may droop," while ants have longer front wings and bent antennae. Getting this wrong in either direction is expensive - either you pay for termite work you don't need, or you ignore actual termites.

Termites matter because of scale. Orkin reports termites damage about 600,000 US homes each year, US residents spend an estimated $5 billion annually controlling them and repairing damage, and a homeowner who finds damage spends an average of $3,000 on repairs. Orkin also notes colonies typically need more than five years to reach a damaging size, though Formosan termites move much faster.

Bed bugs are a cost problem rather than a health-damage problem, and elimination takes time. Rodents are an exclusion problem: sealing entry points is what ends it. Ants vary enormously - carpenter ants damage wood, most others don't. Roaches are a sanitation and harborage problem as much as a chemical one.

One rule this site holds to: any claim that a pest has caused structural damage to your home should be verified by an actual inspection of the structure, not asserted from a photo, a sales visit, or an online description. Damage claims drive expensive work and deserve evidence.