Reference

Pest control glossary

Plain-language definitions of the terms you'll encounter in pest treatment quotes, product labels, and the rest of this site. Written for homeowners — not for entomology graduate students.

A B C D E F G H I L M N O P R S T V

A

Abamectin: An insecticide derived from soil bacteria, commonly used in slow-acting ant and cockroach gel baits. Effective via ingestion at very low concentrations.
Active ingredient: The chemical or biological agent in a pesticide that actually kills, repels, or otherwise affects the target pest. Always listed on the product label as a percentage of the formulation.
Adulticide: A pesticide that targets adult life stages of an insect, as opposed to eggs or larvae.
Aerosol: A pressurized spray product, including "wasp and hornet" sprays, foggers, and contact sprays. Aerosols deliver fast knockdown but typically lack residual effect.
Alates: The winged reproductive form of social insects (especially termites and ants), released seasonally to start new colonies. Also called "swarmers." Indoor sightings often indicate an established colony.
Anticoagulant rodenticide: A class of rodent bait active ingredients (warfarin, bromadiolone, brodifacoum, difethialone) that prevents blood clotting. Effective but raises secondary-poisoning concerns for predators and pets that eat poisoned rodents.

B

Bait: A pesticide formulation that combines an attractant (food, pheromone) with a slow-acting toxicant. The pest carries the bait back to the nest and spreads it to nestmates, often achieving colony-wide effect.
Bait aversion: The learned or genetic preference of a pest population (especially German cockroaches) against a specific bait carrier. The standard remedy is rotating to a bait with a different attractant and active-ingredient class.
Bait station: A tamper-resistant container that holds bait, protecting it from non-target animals and the elements. Standard equipment for outdoor rodent baiting and many ant programs.
Bti (Bacillus thuringiensis israelensis): A biological larvicide that targets mosquito and blackfly larvae specifically. Harmless to humans, pets, fish, pollinators, and most other insects. Sold as granules or "dunks" for standing water.

C

Cephalothorax: The fused head-and-thorax body segment of arachnids (spiders, ticks). Useful for identification — the brown recluse's violin marking is located here.
Conducive condition: Anything in the environment that makes pest infestation more likely: standing water, food residue, gaps in exclusion, excessive humidity, clutter. Removing conducive conditions is the foundation of IPM.
Crack and crevice: A pesticide application targeted into the narrow gaps where pests harbor — behind baseboards, under appliances, in floor seams. Almost always more effective and lower-exposure than open-surface treatment.

D

Diatomaceous earth (DE): A powder made from fossilized diatoms. Abrades the waxy cuticle of insects on contact, causing dehydration. Slow but low-toxicity. Use food-grade DE; pool-filter DE has different particle properties and is not appropriate for pest control.
Drywood termite: A termite group that lives entirely within the wood it consumes, without soil contact. Common in coastal southern U.S. and Hawaii. Treatment usually targets the infested wood directly (spot treatment or whole-structure fumigation).

E

Encasement: A zippered, bed-bug-proof cover for a mattress or box spring. Traps any bugs inside, prevents new ones from harboring, and provides a smooth surface for inspection. A core component of any bed bug treatment plan.
Exclusion: Physically sealing the gaps and openings pests use to enter a structure. Often the highest-value intervention in pest management — addresses the root cause rather than treating symptoms.

F

Fipronil: A potent insecticide used in baits and termite treatments. Highly effective at low concentrations and known for strong colony transfer (treated insects pass the active ingredient to nestmates).
Fogger: A total-release aerosol device ("bug bomb") that disperses insecticide throughout an enclosed space. Generally ineffective against crack-and-crevice pests like cockroaches and bed bugs; can spread pests rather than control them.
Frass: Insect excrement. For carpenter ants and drywood termites, frass appears as small wood-colored pellets accumulating below entry holes — a key visual indicator.
Fumigation: The whole-structure introduction of a gaseous pesticide (commonly sulfuryl fluoride) to penetrate every void and kill all life stages of the target pest. Required for severe drywood termite or whole-house bed bug infestations; not used for subterranean pests.

G

Gel bait: A semi-solid bait formulation applied in small dots in cracks, crevices, and harborage zones. Standard delivery method for ant and cockroach baits.

H

Harborage: The cracks, voids, clutter, and protected spaces where pests rest, breed, and hide. Effective treatment targets harborage rather than the visible foragers.
Horizontal transfer: The spread of a pesticide from one treated pest to others in the colony or population via grooming, food sharing, or physical contact. The mechanism that makes slow-acting baits so effective for social insects.

I

IGR (Insect Growth Regulator): A class of compounds (hydroprene, pyriproxyfen, methoprene, noviflumuron) that interfere with insect development. They don't kill adults directly but prevent reproduction and maturation, breaking the life cycle over weeks. Very low mammalian toxicity.
Indoxacarb: An insecticide activated inside the target insect's body. Common in cockroach gel baits; particularly effective for secondary transfer.
Instar: A developmental stage between molts in immature insects. Cockroach nymphs go through 5–7 instars before adulthood; bed bugs go through 5.
Interceptor: A dish-shaped trap placed under a bed leg that catches bed bugs attempting to climb up or down. Provides both control (cutting off feeding access) and monitoring (visible count of activity).
IPM (Integrated Pest Management): The framework used by universities and public-health agencies for pest control: identify, monitor, modify the environment, treat with the least-toxic effective method, and re-evaluate. The opposite of "spray on a schedule."

L

Larvicide: A pesticide targeting the larval (immature) life stage of an insect — commonly used for mosquitoes and flies before they emerge as biting adults.
Label (the label is the law): The legally binding instructions on a pesticide product. Application rates, target pests, sites, restrictions, and safety precautions are all set by the label. Deviating from label directions is a violation of federal law (FIFRA).

M

Monitor (sticky monitor / glue board): A non-toxic sticky trap used to detect pest activity. Essential for cockroach and rodent programs — captures provide an objective measure of population over time.
Mud tube: A pencil-thin tunnel of soil and saliva built by subterranean termites to travel between soil and wood while staying enclosed. Visible on foundation walls, piers, and joists. A primary diagnostic sign of active termite activity.

N

Neonicotinoid: A class of insecticides (imidacloprid, dinotefuran, clothianidin) chemically similar to nicotine. Effective against many pests; widely used in ant and roach baits. Associated with risks to pollinators when used in flowering plant applications.
Neophobia: The avoidance of new objects in a familiar environment. Strongly developed in house mice, which explains why new traps catch poorly for the first 1–3 nights ("pre-baiting" addresses this).
Non-repellent: A pesticide (commonly fipronil-based termiticides) that pests cannot detect and therefore don't avoid. Allows the chemical to spread through the colony before pests realize anything is wrong — the basis of modern termite treatments.
Nymph: The immature life stage of an insect that undergoes incomplete metamorphosis (cockroaches, bed bugs, true bugs). Visually similar to adults but smaller and not yet reproductive.

O

Ootheca: The egg case produced by cockroaches and some related insects. German cockroach females carry their oothecae until just before hatching; American cockroach females deposit theirs in protected harborage. Each can contain 15–50 eggs.

P

Pheromone trail: The chemical scent trail laid by foraging ants between food and the nest, allowing nestmates to follow the same path. Disrupting the trail temporarily disperses foragers but does not control the colony.
Pre-baiting: Placing unarmed traps with bait for 1–3 nights before arming them, to overcome neophobic avoidance. Substantially increases mouse trap success rates.
Pyrethrin: A natural insecticide derived from chrysanthemums. Fast knockdown, low residual. Often combined with a synergist (PBO) to boost effectiveness.
Pyrethroid: Synthetic analogs of pyrethrin (cypermethrin, deltamethrin, lambda-cyhalothrin, bifenthrin). Longer residual than pyrethrins. The most common active-ingredient class in consumer perimeter sprays. Resistance is widespread in some pest populations, particularly bed bugs.

R

Reservoir: A persistent population or environment that re-seeds infestation. For mosquitoes, a single neglected bucket is a reservoir. For bed bugs in apartment buildings, an untreated adjacent unit is a reservoir. Identifying and addressing reservoirs is often the difference between control and ongoing problems.
Residual: A pesticide formulation that remains effective on a treated surface for an extended period (days to months), continuing to affect pests that contact it. Contrast with contact-only sprays that work only at the moment of application.
Rodenticide: A pesticide intended to kill rodents. The most common categories are anticoagulants (multi-dose and single-dose) and non-anticoagulants (bromethalin, zinc phosphide, cholecalciferol).

S

Secondary poisoning: The unintended poisoning of a non-target animal — typically a predator (owl, hawk, fox) or pet — that eats a rodent which has consumed rodenticide. A primary reason to use tamper-resistant bait stations and prefer single-feed or non-anticoagulant products where possible.
Spot treatment: A targeted pesticide application to a small specific area where pest activity is confirmed, rather than broadcast application across larger surfaces. Lower exposure and often more effective.
Subterranean termite: The termite group that nests in soil and tunnels into wood through mud tubes. Causes the great majority of termite damage in the U.S. Treatment requires liquid termiticide barrier or in-ground bait stations.
Swarm / swarmer: The seasonal release of winged reproductive ants or termites to found new colonies. Indoor swarmers are nearly always meaningful and warrant inspection.

T

Tamper-resistant: Built so that children, pets, and non-target wildlife cannot access the bait inside. Required by EPA for most outdoor rodenticide use.
Termiticide: A pesticide labeled specifically for termite control, typically applied as a soil treatment around and beneath a structure to create a continuous barrier or non-repellent zone.
Trophallaxis: The mutual exchange of food between social insects via mouth-to-mouth feeding. The mechanism by which slow-acting baits spread through ant and termite colonies.

V

Vector: An organism that transmits a pathogen from one host to another. Mosquitoes vector West Nile virus and other arboviruses; ticks vector Lyme disease, anaplasmosis, and others. Vector control is a public-health discipline distinct from nuisance pest control.
Void treatment: A pesticide application — usually dust or aerosol — injected into the hollow space behind walls, in attics, or in similar concealed areas. Common for in-wall yellowjacket nests and German cockroach harborage.

Missing a term? Suggest one and we'll add it.