Is this the same as Terro's other ant baits?

No, and this is the single most important thing to understand before using it. Terro sells true baits — the T300 liquid stations and the T360 dual sweet-and-protein stations — that rely on ants carrying the active ingredient back to the colony undisturbed. T901-6 works completely differently: it's a contact insecticide with residual repellency that kills ants which physically cross the treated granules. Terro's own customer support describes it plainly: it 'targets ants that come into direct contact with it... it will not impact ants that do not walk over the treated zone.' Using bait technique (leaving it dry) or bait expectations (colony transfer) with this product will disappoint you.

Does it actually work?

For what a contact granule can do, yes: watered in correctly along a dry outdoor foundation band or around a mound, it reliably kills ants and other listed insects that cross the treated zone, with residual repellency for weeks. What it does not do is eliminate a colony. The same UC IPM caution that applies to any contact/barrier ant treatment applies here — it kills only the foragers that touch it, not the queen or brood, so the colony can rebuild. Treat it as a surface knockdown and prevention band, not a colony cure.

Do I need to water it in?

Yes — immediately and lightly after applying. Watering activates the lambda-cyhalothrin and moves it into the treated zone where it can kill on contact; left dry, the granules largely sit inert on the surface. For ant mounds specifically, water in gently rather than with a high-pressure spray, since blasting a mound can cause the colony to relocate rather than die in place.

Can I use it indoors?

No — this product is labeled for outdoor use only. It has no role in an indoor ant problem, and applying an outdoor contact granule inside won't reach the source of an interior infestation regardless of how it's applied. If ants are coming from inside a wall void or you're seeing activity indoors, that calls for an indoor bait (kept away from this product) or, if it persists, a professional inspection.

Why do ants keep coming back after I treat the foundation?

Because a contact granule only kills the ants that physically cross the treated zone — the queen and the bulk of the colony stay safely in the nest, untouched, and keep producing new foragers. If ants keep returning despite a correctly watered-in, reapplied band, that's the honest signal to add a bait program in a separate zone, or, for a persistent or structural problem like carpenter ants, to call a licensed professional rather than applying more granules.

Daniel Brady · NH-Licensed Pesticide Applicator · License #782664

How to Use Outdoor Ant Killer Granules (T901-6) by Terro

Situational

Lambda-cyhalothrin 0.04%

Outdoor Ant Killer Granules (T901-6) by Terro work by contact, not by being carried home to a colony — and that puts it in a different category from Terro's own liquid and dual bait stations, despite the shared brand name. Broadcast a 3-to-10-foot band along the foundation (or apply directly to an ant hill), then water it in lightly and immediately per the label — watering is what activates the lambda-cyhalothrin and moves it into the treated zone. Left dry, it underperforms. Terro's own customer support describes the mechanism plainly: it kills ants that physically cross the treated area, not ants that never walk over it. Expect contact kill of exposed ants within about a day and residual repellency for weeks, but don't expect the queen or colony to be touched — that's a job for one of Terro's actual baits (T300 or T360), applied in a separate zone so the repellent granules don't contaminate the bait.

At a glance

Efficacy: Situational
Best job: Knocking down foraging ants and other listed insects that cross a treated outdoor foundation band or spot-treated ant hill
Format: Granular CONTACT insecticide in a resealable shaker bag — broadcast as an outdoor band and watered in after application; outdoor use only
Technique: Easy technique

The honest verdict

Does this product actually work?

The verdict on this product

SituationalEasy technique

Situational

A situational outdoor contact tool, not a colony solution — and distinct from Terro's own liquid and borax baits.

Despite carrying the Terro name alongside the brand's liquid and dual bait stations, T901-6 works on the opposite principle — it's a contact insecticide, not a bait, and Terro's own customer support confirms it: this granule 'targets ants that come into direct contact with it as they move through treated areas... it will not impact ants that do not walk over the treated zone.' Broadcast and watered in correctly, it genuinely knocks down surface-foraging ants and other listed insects in the treated outdoor band. UC IPM's standard caution applies here as much as to any contact/barrier product: it kills only foragers, the colony rebuilds, and it does nothing for an indoor or in-wall source.

Best for

An outdoor foundation band or spot treatment on visible ant hills, knocking down foragers and other listed insects crossing the treated zone.

Skip it for

Eliminating an ant colony (structurally impossible without a carry-back mechanism), any indoor ant problem, and carpenter-ant structural infestations.

Read the label first

What it is — and what it's really for

The label is the law. Here's the honest read on the format, the one job it does well, and the job people wrongly buy it for.

Format

Granular CONTACT insecticide in a resealable shaker bag — broadcast as an outdoor band and watered in after application; outdoor use only

Indoor / outdoor

outdoor

Residual

Provides contact kill plus a residual repellency for weeks after watering in per label; reapply at the label's interval, up to a labeled maximum number of applications per year

Target pests

Ants (as surface foragers, not the colony), Fire ants (mound spot treatment), Cockroaches, Fleas, Ticks, Other listed outdoor crawling insects

Best job

Knocking down foraging ants and other listed insects that cross a treated outdoor foundation band or spot-treated ant hill

Active ingredient

Lambda-cyhalothrin (0.04%)

Not for (honest)

Eliminating an ant colony or nest, or any indoor infestation — this product is labeled outdoor-only and has no carry-back mechanism

The technician's method

The technique walkthrough

Where DIY succeeds or fails is in the placement, patience, and the small pro moves the label never mentions. Follow the label; these are the technique details on top of it.

Easy technique~15-30 min for a foundation band; contact kill within about 24 hours of watering inTools:The resealable shaker bag, A garden hose or watering can, Gloves

The single most important thing to get right is the opposite of a bait: broadcast the granules, then water them in. This product shares Terro's name with two true baits, but its mechanism and technique are entirely different.

Clear the band and confirm dry conditions
Remove leaf litter and cut back vegetation touching the foundation, and apply only when the grass and soil are dry.
Common mistake
Applying to wet or dew-covered ground, which leads to poor, uneven distribution.
Apply a 3-to-10-foot band, or spot-treat a mound
Broadcast a foundation band per the label's width, or apply a smaller measured amount directly around (not on top of) a visible ant hill.
Pro move
Reserve this contact product for the outdoor perimeter and mounds; keep any indoor or bait-based ant program in a separate zone entirely.
Water in lightly and immediately
Water the treated area lightly right after applying — this activates the lambda-cyhalothrin and moves it into the treated zone. For mounds, water in gently; avoid high-pressure spray.
Common mistake
Skipping the water-in step, or blasting a mound with high-pressure water, which can cause the colony to relocate rather than die in place.
Keep people and pets off until dry
Keep children and pets off the treated area until the granules have been watered in and the surface is dry.
Caution
This product is labeled outdoor-use only and is toxic to aquatic life — keep it out of storm drains, ponds, and streams.
Reapply on the label's interval, not reactively
Follow the label's reapplication interval and its labeled maximum number of applications per year rather than reapplying every time an ant reappears.
Common mistake
Treating recurring ant activity as a reason to apply more granules — persistent activity usually means the colony itself is untreated, which this product structurally can't reach.

Habits that decide it

Do & don't

Water in lightly and immediately after broadcasting
Apply to dry turf, never wet or dew-covered ground
Water mounds in gently — no high-pressure spray
Keep kids and pets off until watered in and dry
Keep it in a separate zone from any bait placements

Don't

Don't leave the granules dry expecting ants to carry them home — they won't; this is a contact product, not Terro's borax bait
Don't expect it to reach the queen or the colony
Don't use high-pressure water on mounds — it can scatter the colony
Don't apply it indoors — it's labeled outdoor use only
Don't apply it near or over a bait placement

The honesty moat

Where it works vs. where it fails

No product fixes everything. This is the honest boundary — the situations it genuinely handles, and the ones it simply won't.

Where it works

The goal is knocking down surface-foraging ants and other listed insects along an outdoor foundation band
You're spot-treating a visible ant hill and can water it in gently
It's paired with an indoor bait (T300 or T360), kept in a separate zone, for actual colony control
The problem is genuinely outdoor and surface-level

Where it fails

The goal is eliminating an ant colony or nest — there's no carry-back mechanism
Ants are indoors or in a wall void — the label is outdoor-use only
It's applied near a bait placement (repellent residue contaminates the bait)
The colony is carpenter ants nesting in structural wood
It's left dry without watering in — the granules underperform on the surface

Don't throw money away

Mistakes that waste the product

Not watering it in

This is a contact insecticide, not a bait — without immediate watering, the lambda-cyhalothrin largely stays on the granule surface and underperforms.

Fix

Water in lightly and immediately after applying, per label.

Confusing it with Terro's liquid or T360 bait stations

The bait products rely on ants carrying the active home undisturbed; this granule relies on contact and repellency — using bait technique here (leaving it dry, expecting carry-back) wastes the product.

Fix

Treat T901-6 as a contact/barrier tool, not a bait, and apply the opposite technique: broadcast and water in.

Blasting a mound with high-pressure water

High pressure can cause the colony to relocate rather than die in place, spreading the problem instead of solving it.

Fix

Water mounds in gently with a low-pressure stream or watering can.

Applying near a bait placement

The repellent residue drives ants away from bait they'd otherwise carry back to the colony, undermining any baiting program running nearby.

Fix

Keep this contact-granule zone physically separate from any bait.

Exceeding the label's application frequency

Reapplying reactively every time ants are seen wastes product and can exceed the labeled maximum applications per year without addressing the untouched colony.

Fix

Follow the label's interval and pair with indoor baiting or professional treatment if activity persists.

Calibrated expectations

What to expect — and when

Judge this product on contact knockdown in the treated zone, not on whether ant activity disappears entirely — that requires the colony itself to be addressed.

First ~24 hours after watering in
Contact kill of ants and other listed insects that cross the treated, watered-in band or mound.
Following weeks
Continued residual repellency and contact kill along the treated band, per label.
Ongoing
If the colony or mound queen wasn't directly reached, foraging activity can rebound as new workers replace the ones killed at the surface.

When results plateau

Results plateau when the underlying colony is untouched — a contact granule was never designed to reach it. Persistent activity despite a correctly watered-in, reapplied band signals the need for baiting (in a separate zone) or professional treatment, not more granules.

Know the ceiling

When to stop DIY & call a pro

A contact granule has a real, structural ceiling. These are the honest signals to bridge to a licensed technician:

Ants keep returning despite a correctly watered-in, reapplied treated band
Persistent activity means the colony is untouched — a contact product can't reach the queen or brood.
You see large black ants indoors or moisture-damaged wood
Those point to carpenter ants nesting in structural wood, requiring professional inspection — an outdoor contact granule can't help there.
Ant activity is indoors or seems to originate from a wall void
This product is outdoor-use only per label and never reaches an indoor or in-wall source.
The same ant pressure returns every season despite correct annual treatment
Recurring pressure usually points to a conducive condition or entry-point problem a licensed technician can diagnose and fix at the source.

When a treated perimeter still isn't holding the line, Anchor's licensed NH technicians identify the actual colony or entry pathway and treat the source directly. Free inspection, same-day service across southern and central New Hampshire.

Ants keep coming back after a treated band?

Get a Free inspection (603) 785-0118

Before you treat

Is it safe for pets & kids?

The short version lives here; the full per-species verdict lives on this product's pet-safety page.

Lambda-cyhalothrin contact granules are labeled for outdoor use only and can cause moderate eye irritation on contact. The practical precaution is simple: keep people and pets off the treated area until it's watered in and dry, and never apply it indoors.

Re-entry: Keep children and pets off the treated area until the granules have been watered in and the surface is fully dry.

If there's an exposure, call

ASPCA Animal Poison Control: (888) 426-4435 Pet Poison Helpline: (855) 764-7661 Northern New England Poison Center: (1-800) 222-1222

See the full per-species pet-safety verdict for this product

New Hampshire context

Using a contact granule correctly in New Hampshire

Southern and central New Hampshire's pavement and odorous house ants push indoors as trails warm in spring and again in fall, and a correctly watered-in outdoor band can reduce surface pressure at the foundation. But NH's real structural ant threat is carpenter ants, and this outdoor contact granule was never built to reach a carpenter-ant nest in wood — that's a signal to call Anchor, not to apply more granules. Anchor Pest Services serves Manchester, Nashua, Concord, and the surrounding towns.

Service area

Southern New Hampshire

Anchor Pest Services · NH license #782664 · NEPMA member · family-owned since 2017.

Common questions

Frequently asked

Sources & further reading(6)

[1]
Terro — Outdoor Ant Killer Plus / T901-6 product page
Contact-kill-plus-residual-repellency mechanism, band/mound application directions, water-in instructions, labeled pest list (facts only, not the efficacy verdict)
manufacturerverified 2026-07-14
[2]
Augusta Farmers' Coop — Terro Outdoor Ant Killer Granules spec sheet
Verified active ingredient and concentration (lambda-cyhalothrin 0.04%)
manufacturerverified 2026-07-14
[3]
UC Statewide IPM Program — Ants (Home & Landscape)
Perimeter/contact treatments kill only foraging ants without killing the colony/queens; colony quickly rebuilds
extensionverified 2026-07-14
[4]
Mississippi State University Extension — 'Control Fire Ants in Your Yard'
The bait-vs-contact-granule distinction and why gentle, not high-pressure, watering is used on mounds
extensionverified 2026-07-14
[5]
NPIC — Lambda-cyhalothrin General Fact Sheet
Lambda-cyhalothrin class (pyrethroid) and contact mode of action
npicverified 2026-07-14
[6]
UNH Cooperative Extension — Carpenter Ants Fact Sheet
Carpenter ants as New Hampshire's most troublesome structural ant — a call-a-pro escalation this outdoor granule can't address
extensionverified 2026-07-14

Written & reviewed by

Verified

Daniel Brady

NH-Licensed Pesticide Applicator · License #782664 (NHDAMF, RSA 430)

Daniel Brady is the New Hampshire–licensed applicator behind Anchor Pest Services, a family-owned pest control company serving the Manchester area since 2017.

Verify license

Last updated July 2026

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Professional Pest Control

When a Contact Granule Still Isn't Enough

A treated outdoor band reduces surface foraging, but it can't eliminate a colony, a carpenter-ant nest, or an indoor source. Anchor Pest Services treats the actual source with targeted, licensed methods across southern and central New Hampshire. Family-owned since 2017, NH license #782664.

Get a Free inspection (603) 785-0118

Targeted colony/nest treatment, not just a surface band
NH-licensed applicators (#782664)
Free inspection — same-day service across southern NH

NH License #782664 · No obligation · We answer in person

Keep Exploring

How to Use Outdoor Ant Killer Granules (T901-6) by Terro

Does this product actually work?

What it is — and what it's really for

The technique walkthrough

Clear the band and confirm dry conditions

Apply a 3-to-10-foot band, or spot-treat a mound

Water in lightly and immediately

Keep people and pets off until dry

Reapply on the label's interval, not reactively