🐛 Fall Armyworm Management Guide

Q: What is the economic threshold for fall armyworm in maize?

Most Australian advisories use 5–10% whorl-damaged plants in seedling-to-V6 maize, 10–20% in late vegetative, and zero tolerance at tasseling/silking because the larvae move into protected ear tissue where chemistry can't reach them. Always confirm by opening whorls and counting live larvae — old damage without live caterpillars doesn't justify a spray.

Q: Which insecticide works best on fall armyworm?

Group 28 diamides (chlorantraniliprole, tetraniliprole, flubendiamide) and Group 5 spinetoram consistently give the best efficacy in Australia when applied against L1–L3 larvae before they entrench in the whorl. Group 22A indoxacarb and Group 6 emamectin are strong rotational partners. Pyrethroids and OPs knock down exposed adults and early larvae but fail once caterpillars are in the whorl.

Q: How do I scout for fall armyworm?

Walk 5 transects of 20 plants each per paddock weekly once seedlings emerge. Look for windowpane feeding on young leaves (L1–L2), ragged whorl damage with sawdust-like frass plugs (L3–L6), and egg masses on leaf undersides covered in buff-coloured scales. Open suspect whorls and confirm live larvae — the inverted-Y on the head and four dark spots on the eighth abdominal segment separate FAW from native armyworms.

Q: Is there documented Group 28 diamide resistance in Australian fall armyworm?

Field failures have not been confirmed in Australia as of the latest published surveys, but sensitivity shifts have been detected in populations from Queensland and the Northern Territory consistent with the ryanodine-receptor I4790M and G4946E mutations that drive diamide failure in South America and Asia. Treat Group 28 as a finite resource — maximum two consecutive applications per generation, rotate to Group 5 or 22A, and never chase a poor result with a second diamide.

Q: Do pheromone traps tell me when to spray fall armyworm?

Pheromone traps (Z9-14:OAc + Z7-12:OAc lures) confirm adult flight and signal a likely egg-lay within 3–7 days, but they do not replace larval scouting. A rising trap count is your cue to increase paddock checks — the threshold decision is always made on live larval counts and whorl-damaged plants, not moth numbers.

Q: Can I use Bt sprays like DiPel on fall armyworm?

Yes — Btk (DiPel) and Bt aizawai (XenTari) are registered on FAW and work well against L1–L3 larvae when coverage is good and the pH is 6–8. They are ideal first-choice options in sweet corn (no WHP concerns), organic systems and as early-season softeners that protect beneficials. Efficacy drops sharply on L4+ because consumption is low and the protected toxin needs to be ingested.

Q: What's the best insecticide for fall armyworm in sweet corn?

For seedling–V6 sweet corn, start with a Bt (DiPel/XenTari) or spinetoram (Success Neo/Delegate) to preserve beneficials. From V6–tassel, rotate to a Group 28 diamide (Coragen, Altacor, Vayego) for residual whorl protection. Stop spraying once silks brown — larvae inside the ear are unreachable and further sprays risk residue non-compliance. Always check the current APVMA minor-use permit (PER89241, PER93815) for the specific product and crop combination.

Q: How long does a fall armyworm generation take?

Approximately 30 days egg-to-adult in Australian summer (25–30 °C), stretching to 60 days in spring/autumn (15–20 °C) and 80–90 days during coastal winter. FAW cannot diapause or survive freezing, so southern populations are re-invaded each spring by northward migration from Queensland and the Northern Territory.

Q: Do I need an APVMA permit to spray fall armyworm?

It depends on the crop and product. Several products (Coragen, Altacor, Vayego Forte, Success Neo, Avatar eVo, Proclaim Opti) have FAW on their full APVMA label for specific crops. For many minor crops — sweet corn, ginger, peanuts, popcorn, nursery plants — use is covered by current APVMA emergency/minor-use permits that must be held on farm and followed exactly. Always check the permit PDF on the APVMA portal for the expiry, rates and critical-use comments.

Q: Why do pyrethroids fail on fall armyworm?

Two reasons: coverage and metabolism. Once larvae are L3+, they feed inside the whorl where contact spray can't reach them. And FAW populations carry pyrethroid-detoxifying cytochrome P450 alleles inherited from decades of pyrethroid exposure in the Americas — baseline susceptibility was already low on arrival in Australia. Reserve pyrethroids for adult knockdown on field margins or early-L1 infestations with excellent canopy penetration.

The invasive that reset every summer-crop IPM program east of the WA border. Spodoptera frugiperda arrived in the Torres Strait in January 2020 and inside 24 months had established across every tropical and sub-tropical grain-growing region of Australia.

This is a field manual — built for the grower walking a maize paddock at dawn. The central principle is unchanged from every other IPM program: scout early, threshold accurately, rotate modes of action, and don't chase resistance. What's different with FAW is the pace. A generation takes 30 days in a Queensland summer. Miss the L1–L3 window and the crop takes a 20–40% hit.

Jan 2020 first detected 6 instars 8 IRAC groups 30 days egg-to-moth 90+ APVMA permits

Intro

Spodoptera frugiperda — fall armyworm, or FAW — was first detected in Australia on the Torres Strait islands in January 2020 and on the Bamaga mainland the following month. Inside 24 months it had established across every tropical and sub-tropical grain-growing region in the country. FAW is a migratory noctuid moth from the Americas with a voracious larval appetite for grass crops: maize, sorghum, sweet corn, rice, sugarcane and turf all take direct hits, and more than 350 host plants have been recorded worldwide. It out-breeds, out-migrates and out-eats the native armyworms Australian growers had managed for decades with a pyrethroid and an OP.

This guide exists because three things happened simultaneously: FAW arrived, growers needed answers in days not months, and the Australian chemistry market scrambled onto emergency and minor-use permits to fill the gap. By early 2026 there are over 90 APVMA permits covering FAW across crops and situations. That's a lot of label reading. The outline below pulls it together into a single field manual — built for the grower walking a maize paddock at dawn, not for a literature review.

Read this in order the first time

Intro → Why it matters → Arrival → Species → Lifecycle → Scouting → Thresholds → IPM → Trapping → Chemistry → Products → Resistance → Calendars → How-to → Legal → FAQs. Then bookmark the chemistry and product sections as field reference.

Why it matters

Yield loss, residue risk, resistance risk — the business case for getting this right first time.

Global FAW yield loss estimates for maize run 8.3–20.6 million tonnes annually in the 12 largest African producers alone (CABI 2020). Australian modelling by GRDC and CSIRO has pencilled in $2 billion of potential loss to sorghum, maize and sweet corn over the first five years of establishment if chemistry and agronomy don't keep pace. The actual figure through 2025 has been lower — thanks to fast permit approvals, grower adoption of scouting, and the good fortune that FAW arrived when Group 28 diamides were still highly effective — but the margin for complacency is gone.

Three things separate FAW from the native armyworm complex (Mythimna convecta, Persectania ewingii) that growers knew:

It doesn't diapause. Native armyworms overwinter as pupae; FAW does not. Populations rebuild each spring from northward migration out of coastal QLD and the NT. Southern NSW and Victorian infestations are almost always second-generation immigrants by mid-summer.
It hides in the whorl. From L3 onwards, larvae plug themselves inside the tightly rolled maize/sorghum whorl where contact chemistry can't reach them. Pyrethroid sprays that knock down native armyworm in open canopy routinely fail on entrenched FAW.
It carries a pre-selected resistance genetic background. Decades of pyrethroid, OP and carbamate use in the Americas selected for metabolic resistance and target-site mutations (e.g. ryanodine-receptor I4790M for diamide resistance in some Asian populations) that have arrived with the moth. The working chemistry in Australia is narrower than the label list suggests.

Residue risk: FAW is listed on numerous minor-use permits for crops where the product is not on the full label. Permit WHPs, export intervals and critical-use comments must be followed exactly — a trade rejection on a $200k sweet corn consignment because a spray went on two days late is the most expensive "failure" in this guide.

Arrival timeline & state presence

How it got here, how it spread, where it sits now.

Date	Location	Notes
Jan 2020	Erub & Saibai Islands (Torres Strait)	First Australian detection by Biosecurity Queensland.
Feb 2020	Bamaga, Cape York (QLD mainland)	Established mainland population — national response shifted from eradication to management.
Mar–Jun 2020	Central & Southern QLD, Northern NT	Rapid spread through the Burdekin, Bowen Basin, Atherton Tablelands, Katherine region.
Late 2020	Kununurra (Kimberley, WA)	First WA detection — now considered endemic to the Kimberley and Ord.
2021	Northern NSW	Reached the North Coast, Northern Tablelands, Liverpool Plains.
2022	Central NSW & Northern VIC	First confirmed larvae in summer grain regions south of the Dividing Range.
2023	Southern VIC, Northeast SA	Pheromone-trap-only detections become regular; larval populations transient and migratory.
2024–2026	Permanent core: northern QLD, NT, Kimberley WA. Seasonal southern incursions across NSW, VIC, SA.	No confirmed establishment in Tasmania. WA south of the Kimberley remains low-pressure.

Practical implication: Growers in QLD and NT manage FAW every summer. NSW growers plan for it but variable year-on-year. VIC, SA and southern WA see sporadic pressure tied to monsoon troughs pushing moths south in January–March.

Species & look-alikes

FAW vs native armyworms, cluster caterpillar and Helicoverpa — the ID mistakes that drive the wrong spray.

🐛🔍 ZoomSpodoptera frugiperda

Fall armyworm

Spodoptera frugiperda

Pale inverted-Y mark on head capsule. Four prominent dark spots in a square on the 8th abdominal segment. Larva dark to yellow-brown with pale longitudinal stripes. Adult wingspan 32–40 mm; males have a distinct white spot on forewing.

Invasive (2020)Grasses + 350 hostsMigratory

🪲🔍 ZoomMythimna convecta

Common armyworm

Mythimna convecta

Native. No Y-mark, no square of spots. Usually greenish-brown with narrow dorsal stripes. Major pasture pest in winter cereals. Overwinters in southern Australia — populations build slowly compared to FAW.

NativeWinter cereals

🐛🔍 ZoomPersectania ewingii

Southern armyworm

Persectania ewingii

Native. Darker than common armyworm with a prominent pale dorsal stripe. A cool-climate pasture and cereal pest in VIC, TAS and southern SA/WA. Rarely a problem in summer crops.

NativeTemperate

🪲🔍 ZoomSpodoptera litura

Cluster caterpillar

Spodoptera litura

Native Spodoptera. Gregarious early instars leave skeletonised patches. No inverted-Y; darker head with a pair of lateral black spots on each segment. Many chemistry groups overlap with FAW but the best treatment windows differ.

Native SpodopteraBroadleaves + grasses

🐛🔍 ZoomHelicoverpa armigera

Cotton bollworm / Heliothis

Helicoverpa armigera

Not an armyworm. Larger at maturity, variable colour (green / brown / pink), bores into fruit and reproductive tissue (cobs, heads, bolls). Chemistry overlaps strongly with FAW (Group 28, 5, 22A) but scouting threshold and timing differ.

Major crop pestBoring damage

🦗🔍 ZoomHerpetogramma licarsisalis

Lawn armyworm / sod webworm

Herpetogramma licarsisalis

Different species, different family. Small green-brown larvae, web-tunnel feeders in turf. Frequently confused with FAW in lawn settings — FAW adults lay eggs directly on turf blades and damage is chewing, not tunnelling.

TurfEasily mistaken

Rule of thumb: If you can see the inverted-Y on the head and four dots on segment 8, it's FAW. If neither is present, it's almost certainly a native species — the IPM plan changes.

Lifecycle at a glance

Six instars, four life stages, one 30-day window.

1

Egg mass

2–3 d @ 25 °C

Dome-shaped eggs (~0.4 mm) laid in clusters of 100–200 on leaf undersides, covered in buff-coloured abdominal scales from the female. A single female lays 1,500–2,000 eggs over 2–3 nights. Near-flat, cream to pink, darkening just before hatch.

2

L1–L2 larvae

3–4 d

Neonates skeletonise leaf tissue, leaving "windowpane" damage between veins. Still exposed on leaf surface, highly susceptible to all registered chemistry. Cannibalistic — only 1–2 larvae survive per whorl by L3.

3

L3–L4 larvae

4–5 d

Larvae enter the whorl and begin protected feeding. Frass plugs appear at the whorl opening. Still susceptible to systemic/translaminar chemistry (diamides, emamectin) but coverage with contact products is already reduced.

4

L5–L6 larvae

6–10 d

Mature caterpillar, 38–51 mm. Feeding rate escalates — 80% of total larval damage occurs in the final two instars. Deep in the whorl or moved to the reproductive tissue (tassel, silk, young cob). Chemistry options collapse.

5

Pupa

7–13 d

Final-instar larva drops from the plant and tunnels 2–8 cm into the soil. Pupates inside a loose earthen chamber. Cannot diapause — dies in freezing soil. Undisturbed by cultivation at normal tillage depths.

6

Adult moth

10–21 d

Nocturnal, strong flier. Single flight 100+ km on favourable winds. Mates within 24 h of emergence. Females begin egg-laying 3–5 d post-emergence. Adult survival drops sharply in hot dry conditions without nectar.

Generations per year: 4–6 in the NT and coastal QLD, 2–4 in inland NSW, 1–2 incomplete generations in southern NSW and VIC (all re-invaded from the north each spring). FAW cannot survive freezing temperatures or enter diapause — southern Australia is annually re-colonised by migration.

Scouting — what to look for and when

Five signs, five paddock transects, once a week from emergence.

Scouting FAW is not a one-off walk — it's a weekly schedule from emergence through to the close of the vulnerable window (tassel in maize, boot in sorghum, silk in sweet corn, any stage in turf). Walk 5 transects of 20 plants per paddock, recording what you see stage-by-stage. The goal is to catch the population at L1–L3, before larvae move into the whorl.

Egg

Egg masses

Cream to pink clusters of 100–200 eggs on leaf undersides, covered in tan fuzzy scales. Most common on upper leaves near the whorl. Hatch in 2–3 days.

L1–L2

Windowpane feeding

Small transparent patches of leaf epidermis between major veins — neonates eat the green mesophyll but leave the cuticle. First visible sign of establishment.

L3–L4

Ragged whorl damage

As the whorl unfurls, symmetrical rows of holes or tears appear in the lamina. Fresh damage has live sap; old damage is browned at the edges.

L3+

Frass plugs

Sawdust-coloured larval excrement packed into the whorl opening. Biggest single diagnostic — if the whorl is plugged with frass, there's a live L3+ larva inside.

L5–L6

Tassel / ear damage

Late-instar larvae move to reproductive tissue. Chewed tassel bracts, tunnelling into silks, entry holes in young cobs. Chemistry options collapse at this point.

Turf

Brown patches on lawn

Sudden 0.5–1 m diameter scalped patches in couch, kikuyu or buffalo. Hold a torch at night — larvae feed from dusk. Check birds flocking to the patch.

Open the whorl. Damage without live larvae is not a reason to spray — FAW moves fast and caterpillars cannibalise each other. Confirm live L1–L3 before pulling the trigger.

Economic threshold decision matrix

Don't spray under threshold. Don't wait over it.

Crop	Stage	Action threshold	Priority chemistry
Maize (grain/silage)	VE–V6 (seedling to 6-leaf)	5–10% plants with live L1–L3 larvae and fresh damage	Bt · spinetoram · diamide
	V7–V12 (late whorl)	10–20% damaged whorls + live larvae	Group 28 diamide · Group 22A
	VT–R2 (tassel to blister)	Not economic — larvae in protected tissue; preserve beneficials	Generally no treatment
Sorghum	Seedling to boot	10–20% whorl-damaged plants + live L1–L3	Diamide · spinetoram · Bt
Sorghum	Flowering + grain fill	Head infestation rare — pay attention to Helicoverpa threshold instead	Group 28 if both species present
Sweet corn	Emergence to V6	5% plants with live larvae (higher tolerance because preventive programs)	Bt (first) · diamide
	V7 to tassel	10% plants with fresh whorl damage	Diamide · indoxacarb · spinetoram
	Silking onward	Zero tolerance — larvae enter ear	Stop spraying once silks brown; WHP & residue critical
Turf (couch/kikuyu/buffalo)	Any	2–3 larvae per 0.1 m² or visible scalping	Indoxacarb · diamide · spinetoram
Pasture (forage grasses)	Any	10+ larvae per m² + visible defoliation	Diamide · pyrethroid (if L1–L2 exposed) · Bt

Don't mistake damage for presence. In high-migration summers, adult moths can blow through and lay eggs that predators clean up before threshold is reached. Always count live larvae, not just damage symptoms.

IPM pyramid — stacking the deck before chemistry

Every tactic in the stack lowers the spray bill and pushes back the resistance clock.

1

Crop placement & timing

Early uniform planting shortens the vulnerable whorl window. Avoid staggered planting dates — they create a continuous egg-lay substrate.

2

Varietal tolerance

Bt-transgenic maize (Cry1F, Cry1Ab, Vip3A stacks) where available. In Australia, non-GM sweet corn and conventional maize dominate — varietal tolerance is limited but new Bt-pyramided lines are in trials.

3

Biological control

Preserve Trichogramma pretiosum egg parasitoids, Telenomus remus, earwigs, spiders, predatory ants. One broad-spectrum pyrethroid in the seedling stage wipes the beneficial slate for weeks.

4

Pheromone mass trapping

Field-scale delta or bucket traps reduce adult populations at known hotspots. More useful as a monitoring tool than as standalone control — pair with border sprays at high trap counts.

5

Soft chemistry first

Bt (DiPel, XenTari), nucleopolyhedrovirus (Fawligen, Spodovir Plus), spinetoram — use these for the first threshold spray. Low selection pressure on the reserve Group 28 diamides.

6

Synthetic chemistry — rotated

Group 28 → Group 5 → Group 22A → Group 6 across generations. Never two consecutive applications of the same group within a generation or across back-to-back generations.

Pheromone trapping

Trap counts are a warning, not a threshold.

Fall armyworm male moths are attracted to synthetic lures based on (Z)-9-tetradecenyl acetate (Z9-14:OAc) as the main component, typically blended with (Z)-7-dodecenyl acetate (Z7-12:OAc) to improve species specificity. Lures are sold by several Australian suppliers (AgBiTech, Sumitomo, Trécé) with 4–6 week field life. Traps are single-use buckets (lean-on trap), green delta traps, or large Funnel-type units for mass trapping.

Deployment

Density: 1 trap per 20 ha for monitoring; 2–4 traps per 20 ha for mass-trapping programs.
Position: crop edge, aligned into prevailing wind. Trap mouth at crop-canopy height and raised as the crop grows.
Check interval: weekly. Count, clear, replace lure per manufacturer interval.
Data use: the trap count tells you adult activity. A sudden 3–5× weekly increase signals an imminent egg-lay — begin intensive larval scouting within 3–7 days.

Traps do not replace scouting. The threshold decision is always live-larval count. A high trap count without subsequent in-crop establishment (common when the moth flight overflies the district) does not justify a spray.

Chemistry overview

The 8 IRAC groups registered (or permitted) for FAW in Australia, ranked by field performance.

IRAC	Class	Key actives (Aus)	L1–L3 efficacy	L4+ efficacy	Residual	Resistance status
28	Diamide (ryanodine receptor)	Chlorantraniliprole, tetraniliprole, flubendiamide, cyclaniliprole	Excellent	Good (translaminar)	10–21 d	Global: confirmed. Aus: shifts detected; no field failures.
5	Spinosyn (nAChR allosteric)	Spinetoram, spinosad	Excellent	Moderate	5–10 d	Global: confirmed in H. armigera. Aus FAW: no failures reported.
22A	Oxadiazine (Na-channel blocker)	Indoxacarb	Very good	Moderate	5–10 d	Low resistance signal in Aus FAW.
6	Avermectin (GluCl activator)	Emamectin benzoate	Very good	Good (translaminar)	5–7 d	Low resistance signal.
11	Bt (microbial)	Btk (DiPel), Bt aizawai (XenTari), NPV (Fawligen)	Good	Poor	3–5 d (UV-limited)	Essentially zero. Ideal rotation partner.
18	Ecdysone agonist (IGR)	Methoxyfenozide, tebufenozide	Good (delayed)	Moderate	7–14 d	Low signal. Use with L1–L3 only.
1A	Carbamate (AChE)	Methomyl, carbaryl	Moderate	Poor	2–4 d	Pre-existing global resistance arrived with moth.
1B	Organophosphate (AChE)	Acephate, trichlorfon, chlorpyrifos (restricted)	Moderate	Poor	3–7 d	Widespread pre-existing resistance.
3A	Pyrethroid (Na-channel modulator)	Gamma-cyhalothrin, alpha-cypermethrin, lambda-cyhalothrin, tau-fluvalinate	Moderate (L1–L2 only)	Fails	3–5 d	Baseline susceptibility low. Often fails field-standard on L3+.

Pyrethroid caveat: a pyrethroid on L3+ FAW inside the whorl is the single most common reason for "product didn't work" calls. It's a coverage problem compounded by baseline resistance. Reserve pyrethroids for L1–L2 in seedling crops with full canopy coverage, or adult knockdown on trap-bait margins.

Group 28 diamides — the FAW workhorse

Use them well, use them sparingly, rotate them out.

Diamides bind the ryanodine receptor in muscle and nerve tissue, causing uncontrolled calcium release, paralysis and death. They are translaminar (penetrate leaf tissue), moderately systemic, and survive rain-fastness within 60–90 minutes of application. For FAW, diamides are the most reliable single mode of action available — but they are also the most valuable. South American, West African and Asian populations have developed field-failing resistance through the ryanodine-receptor mutations I4790M and G4946E, plus metabolic detoxification via enhanced cytochrome P450 expression.

IRAC 28 Chlorantraniliprole

The original diamide and the most widely used FAW chemistry globally. Excellent efficacy on L1–L4, good on L5. Registered products in SprayHub: Coragen, Altacor X-Force. Rates typically 20–60 mL/ha (Coragen 200 SC) or 30–80 g/ha (Altacor 700 WG) — always confirm on the specific label/permit.

WHP maize 7 d · sorghum 14 d · sweet corn variable by permit. Residual 10–21 d.

IRAC 28 Tetraniliprole

Newer diamide with slightly different binding kinetics; cross-resistance with chlorantraniliprole is variable in field populations. Excellent on L1–L4, good L5. Products: Vayego 200 SC and Vayego Forte (480 g/L). Strong choice for the second diamide slot in a rotation when chlorantraniliprole has been used in the previous generation.

Translaminar. Rainfastness 60 min. Residual 10–14 d.

IRAC 28 Flubendiamide

Product: Belt 480 SC. Historically strong Helicoverpa chemistry, also effective on FAW. Narrower crop registration profile in Australia — confirm label before use.

Contact + ingestion. Residual 10–14 d.

IRAC 28 Cyclaniliprole

Product: Nufarm Teppan 50 SL. Lepidopteran-active diamide, slightly softer on beneficials than chlorantraniliprole. Used in horticulture; FAW label/permit coverage varies.

Check APVMA permit for FAW use on specific crops.

Hard rule: never two consecutive applications of a Group 28 diamide in the same FAW generation, and never more than two total diamide applications per crop per season. When a diamide spray underperforms at the correct timing and rate, do not re-apply the same chemistry — switch to Group 5 or 22A and lodge a sensitivity check.

Group 5 spinetoram — the rotation anchor

Fast knockdown, moderate residual, excellent L1–L3 efficacy.

Spinosyns are fermentation products of Saccharopolyspora spinosa that bind nicotinic acetylcholine receptor at a unique allosteric site. Spinetoram (Group 5) is the semi-synthetic successor to spinosad with roughly 3–5× potency on lepidoptera. It is the standout soft-chemistry rotation partner for Group 28 on FAW — comparable efficacy at L1–L3, excellent worker-safety profile, and fits most IPM programs including organic horticulture (spinosad).

IRAC 5 Spinetoram

Products: Success Neo Jemvelva (120 g/L SC), Success Ultra, Delegate (250 g/kg WG). All carry FAW on full label or current minor-use permit across maize, sorghum, sweet corn and vegetables.

UV-sensitive — apply late afternoon where possible. Rainfastness ~1 h. Residual 5–10 d.

Permit coverage: spinetoram for FAW in sweet corn, popcorn, maize popcorn and some vegetables is on APVMA permits PER89241, PER93482, PER93550, PER89870 (spinosad). Always carry a printed copy of the current permit to every spray day.

Group 22A indoxacarb

The third-spray rotation option.

Indoxacarb is a sodium-channel blocker activated by insect esterase metabolism — it is effectively a pro-insecticide that becomes toxic inside the larva after ingestion or contact. Moderate-to-good efficacy against FAW L1–L4, fading on L5+. The primary rotation role is as the third unique mode of action in a season — filling the slot where a third Group 28 or Group 5 spray would push resistance pressure too hard.

IRAC 22A Indoxacarb

Products: Avatar eVo (303 g/kg WG), Surefire Assault 150 EC, and PLEMAX (indoxacarb + novaluron — Group 15 + 22A mixture; the 15 adds IGR activity on young larvae).

Stomach + contact. Rainfastness ~1 h. Residual 5–10 d. APVMA permit PER93488 (maize cereals), PER93815 (sweet corn).

Bt biologicals & NPV — the softening partner

Preserves beneficials. Low resistance selection. Fits sweet corn, organic and first-spray programs.

Bacillus thuringiensis produces crystal (Cry) and vegetative insecticidal (Vip) proteins that bind the larval mid-gut lining, forming pores that cause gut paralysis and starvation. Two subspecies are widely used on FAW:

Btk (Bt subsp. kurstaki) — broad lepidopteran activity. Product: DiPel DF.
Bta (Bt subsp. aizawai) — stronger on Spodoptera including FAW. Product: XenTari WG.

Bts are stomach poisons only — the larva must eat treated tissue. Efficacy on L1–L3 is good with dense coverage; drops sharply on L4+ due to reduced feeding rate and protected whorl position. UV degradation shortens residual to 3–5 days — apply late afternoon and reapply after heavy rain.

Nucleopolyhedrovirus (NPV)

Two permit products: Fawligen (SfMNPV strain 3AP2, PER90820) and Spodovir Plus (PER91477). FAW-specific baculoviruses that replicate inside ingested larvae and kill within 4–10 days. Slow-acting relative to chemistry — plan the economic window around a 7–10 d kill curve, not 24–48 h.

Best use: the first spray of the season against L1–L3 in sweet corn or organic systems, paired with spinetoram in rotation. Preserves beneficials, avoids resistance selection on the premium chemistry, and sets up a cleaner rotation for the rest of the season.

Registered products in SprayHub

The FAW-active lineup currently in the app — tap any card for the full label.

Group 28 — Diamides (first choice)

Month	Crop stage	Action
Aug–Sep	Pre-plant	Deploy pheromone traps. Review last season's resistance management.
Oct	Sowing	First scout at emergence. Threshold spray if L1–L3 established.
Nov	V3–V6	Weekly scouting. Bt or spinetoram preferred first spray.
Dec	V7–V12 (whorl)	Peak risk. Group 28 diamide for in-whorl protection.
Jan	VT–R1 (tassel/silk)	Reduce sprays — larvae in protected tissue. Preserve beneficials.
Feb–Mar	R3–R6 (grain fill)	Monitor only. Consider Helicoverpa threshold if cobs attacked.
Apr	Harvest	Record all sprays applied. Remove trap stations. Plan next season's rotation.

Month	Crop stage	Action
Sep–Oct	Pre-plant	Traps up. Volunteer control — FAW survives on summer weeds.
Nov	Seedling	Weekly scouts. Spinetoram or diamide at threshold.
Dec–Jan	Whorl to boot	Highest-risk window. Group 28 rotation with Group 5.
Feb	Head emergence	Switch focus to Helicoverpa if both species present — diamide covers both.
Mar–Apr	Grain fill	Monitor only. Usually below threshold.

Stage	Action
Emergence	Start Bt or spinetoram at first L1 detection. Preserve beneficials for downstream blocks.
V4–V7	Second spray — Group 28 diamide if pressure rising. Always check current APVMA permit.
V8–tassel	Third spray (if needed) — switch to Group 22A or Group 6. Never a second Group 28 within a crop.
Silking	Stop spraying once silks brown. WHP + residue critical for export/domestic compliance.
Harvest	Record everything. Trash management — destroy stubble within 4 weeks to break the breeding cycle.

Season	Action
Spring	Monitor at first warming (18 °C+ night minimums). Look for sparrow/ibis activity as early indicator.
Summer	Weekly walks at dusk with torch. Threshold: 2–3 larvae per 0.1 m² or visible scalping. Indoxacarb or diamide — rotate across generations.
Autumn	Peak risk on north-facing slopes and freshly fertilised blocks. Second spray window.
Winter	Little activity south of Brisbane. Ongoing threat in Cairns / NT coastal.

🐛 Fall Armyworm Guide

🐛 Fall Armyworm Management Guide

Intro

Read this in order the first time

Why it matters

Arrival timeline & state presence

Species & look-alikes

Fall armyworm

Common armyworm

Southern armyworm

Cluster caterpillar

Cotton bollworm / Heliothis

Lawn armyworm / sod webworm

Lifecycle at a glance

Scouting — what to look for and when

Egg masses

Windowpane feeding

Ragged whorl damage

Frass plugs

Tassel / ear damage

Brown patches on lawn

Economic threshold decision matrix

IPM pyramid — stacking the deck before chemistry

Pheromone trapping

Deployment

Chemistry overview

Group 28 diamides — the FAW workhorse

IRAC 28 Chlorantraniliprole

IRAC 28 Tetraniliprole

IRAC 28 Flubendiamide

IRAC 28 Cyclaniliprole

Group 5 spinetoram — the rotation anchor

IRAC 5 Spinetoram

Group 22A indoxacarb

IRAC 22A Indoxacarb

Bt biologicals & NPV — the softening partner

Nucleopolyhedrovirus (NPV)

Registered products in SprayHub

Group 28 — Diamides (first choice)

Coragen® Insecticide

Altacor® X-Force

Vayego Forte®

Vayego® 200 SC

Belt® 480 SC

Nufarm Teppan 50 SL

Group 5 — Spinosyns

Success Neo Jemvelva

Corteva Success Ultra

Delegate®

Group 22A — Indoxacarb & mixtures

Avatar® eVo

Surefire Assault 150 EC

PLEMAX / Quali-Pro Twister

Group 6 — Avermectin

PROCLAIM® Opti

Group 11 — Bt biologicals

DiPel® DF

XenTari® WG

Group 18 — Ecdysone agonists (IGR)

Prodigy®

Imtrade Ecdypro 700 WP

Group 1A / 1B — Carbamates & OPs (knockdown only)

Sinmas 225

Nufarm Methomyl 225

Bugmaster Flowable

Lancer® 970

Imtrade Tyranex 500

Group 3A — Pyrethroids (reserve; L1–L2 only)

FMC Trojan®

Alpha-Scud® 300 SC

Karate® Zeon

Resistance management — the non-negotiables

The three rules

Tank-mixing

Crop calendars

Maize (grain / silage) — QLD & northern NSW

Sorghum — Qld Darling Downs / NSW Liverpool Plains

Sweet corn — year-round staggered plantings (coastal QLD)

Turf (couch / kikuyu / buffalo)

How to — the 8-step FAW playbook