Citrus aphids, thrips and whitefly: identification and when to spray Py-Bo

Citrus carries more sucking pests than most tree crops. The ones that sit on flush, flowers and the undersides of leaves — aphids, thrips, whiteflies, and leafhoppers where they occur — are the pests this page is for.

This is an on-label hub for Australian citrus growers and anyone searching citrus aphids, citrus thrips, Kelly’s citrus thrips, citrus whitefly or citrus leafhopper. Product discussed: Py-Bo Natural Pyrethrum Insecticidal Concentrate (APVMA 53738; 80 g/L pyrethrins + 320 g/L piperonyl butoxide, EC). Always read the current APVMA-approved label. The label is the law.

Citrus sits under the labelled horticultural situation “fruit and vegetable crops, cut flowers and ornamental plants.” Confirm that on the pack in the shed before you mix. Do not invent rates or pests.

On the Py-Bo label — and what is not

The current public Py-Bo horticultural pest list (APVMA 53738) is: aphids, ants, cabbage moth and other caterpillars, earwigs, leafhoppers, thrips, whiteflies.

That is the claim. Exposed nymphs and adults of those pests, on labelled fruit (including citrus), are the job. Coverage is the job. Contact is the job.

Not named on that horticultural list — and not claimed here: Queensland fruit fly (QFF), citrus leaf miner, citrus gall wasp, bronze orange bug, spined citrus bug, scales, mealybugs, mites, weevils and grasshoppers. Pyrethrum is contact only. It does not move in sap and it does not reach larvae inside fruit, leaf mines or woody galls.

Identification

Citrus aphids

Look on the growing tips. Black citrus aphid (Toxoptera citricida, also called brown citrus aphid) colonies cluster on flush, young leaves and flowers. Nymphs are pear-shaped, red-brown to black, about 1–2 mm. Adults are shiny black, about 2 mm, winged or wingless. Spiraea aphid (Aphis spiraecola) is yellow-green and less common in some districts. Other coloured aphids turn up on citrus too; the label names aphids, not one species.

They push their mouthparts into thin tissue. Sap pressure does most of the work. Honeydew drips onto leaves and fruit, ants move in for a cheap feed, and sooty mould follows. Curled flush on young trees is the damage that costs. In warm weather a generation can turn over in about a week; females produce live young (no eggs to wait on). Winged adults mean the colony is crowded or the flush is going off.

Citrus thrips (including Kelly’s citrus thrips)

Thrips often arrive in a swarm, including from native vegetation and pale flowers. They like the same buds and shoots as aphids — and the whiteness of citrus blossom.

Kelly’s citrus thrips (Pezothrips kellyanus) is the species that scars Australian citrus fruit. Adults are black, about 1–3 mm, with fringed wings. Larvae are pale yellow to bright orange, up to about 2 mm. They hide under the calyx and where fruit touch. Feeding scrapes the rind: halo scarring around the calyx, and scurfing that looks like wind rub. Navel and Valencia oranges, lemons and grapefruit take the worst of it. The critical window is petal fall through calyx closure (often mid-October to late November in southern districts, into December).

Plague thrips and other flower thrips can be in blossom at the same time. A 10× lens helps; orchard history and black adults in flowers are a practical field call. Eggs are inserted in tissue. Larvae do most of the fruit damage. Pupae are often off the fruit, in debris or protected sites. The label names thrips.

Citrus whiteflies

Australian citrus whitefly (Orchamoplatus citri) and other whiteflies sit on the undersides of leaves. Adults are tiny (about 1.5 mm), moth-like, with white-waxed wings. A disturbed canopy throws up a small white cloud. Eggs are laid on the underside. Crawlers walk a short way, then nymphs settle, go scale-like and stop moving. Honeydew and sooty mould on leaves and fruit are often what you notice first.

Contact spray has to wet the underside. Adults and young nymphs are the stages you can hit. Eggs and pupae are much harder. The label names whiteflies.

Leafhoppers (citrus jassid), if present

The Australian citrus leafhopper (Distantasca smithi, citrus jassid) is a small lemon-yellow hopper, about 2.7–2.9 mm, on eastern seaboard citrus. It causes chlorosis and distortion on new foliage, and oleocellosis-like spots 3–10 mm across on green and ripening fruit. Nymphs and adults feed on the canopy. The label names leafhoppers. If they are in the block, they are an on-label horticultural pest. If they are not, do not go looking for a reason to spray.

Contact versus not

Py-Bo kills by contact. If the droplet does not hit the insect, the insect does not die. It is not systemic. It is not residual in the plant. UV breaks pyrethrins down in a few hours of sunlight — that is why the withholding period is one day, and why you re-treat on the next hatch, not on a six-week “protection” interval.

Pest	On Py-Bo horticultural label?	Hit by a foliar contact spray?
Aphids (nymphs and adults on flush)	Yes	Yes, if droplets contact them on tips, flowers and young leaves
Thrips (adults and larvae on flowers, calyx, touching fruit)	Yes	Yes, if coverage reaches calyx, blossom and contact points. Eggs in tissue: no. Pupae off-fruit: no
Whiteflies (adults and young nymphs on undersides)	Yes	Yes, if undersides are wet. Eggs and pupae: much harder
Leafhoppers / jassids	Yes	Yes, if nymphs and adults are contacted
Ants tending honeydew	Yes	Yes, workers on the canopy if contacted — not a nest treatment
Exposed caterpillars	Yes (cabbage moth and other caterpillars)	Yes, if larvae are on the surface and hit
Earwigs	Yes	Yes, if contacted
Queensland fruit fly maggots in fruit	No	No — inside the fruit. Follow local QFF programs
Citrus leaf miner larvae in mines	No	No — inside the leaf
Citrus gall wasp larvae in twigs	No	No — inside woody galls
Bronze orange bug, spined citrus bug	No	Not a registered claim. Do not treat this page as a bug registration
Scales and mealybugs	No	Waxy coverings shed water-based contact sprays. Not named on the horticultural list
Mites, weevils, grasshoppers	No	Not named horticultural pests on this label

How to spray Py-Bo (1 mL/L, 1-day WHP)

Product: Py-Bo Natural Pyrethrum Insecticidal Concentrate (APVMA 53738)
Actives: 80 g/L pyrethrins + 320 g/L piperonyl butoxide (PBO), emulsifiable concentrate
Mode: contact only. Knockdown of insects the spray actually hits. Not systemic. Not residual in the plant. Pyrethrins break down rapidly in sunlight.
Labelled horticultural situation: fruit and vegetable crops, cut flowers and ornamental plants. Citrus is fruit — confirm on the current label.
Labelled horticultural pests: aphids, ants, cabbage moth and other caterpillars, earwigs, leafhoppers, thrips, whiteflies.
Rate on that labelled horticultural use: 1 mL Py-Bo per 1 L water, or 100 mL per 100 L water. Do not invent another rate.
Withholding period: 1 day on labelled edible plants (do not harvest for 1 day after application). Spray today, pick tomorrow where the label allows. Confirm crop listing and WHP on the current label.

Mix 1 mL/L (100 mL/100 L) in clean water only if that is the rate on the label for your situation.
Apply so droplets contact the pests: growing tips and flowers for aphids; blossom, calyx and fruit-touch points for thrips; undersides for whiteflies and leafhoppers. Thorough coverage of all foliage, including undersurfaces, is what the horticultural use requires.
Prefer dusk / after dark. Do not spray plants in flower while bees are foraging.
If live pests remain after the spray has dried, they were not contacted. Change volume, droplet size or nozzle angle on a test run.
Follow up when the next hatch is visible. Aphids can turn a generation in about a week. Thrips eggs in tissue and whitefly eggs on the underside survive the first pass. That is a hatch interval, not a calendar residual.

Py-Bo is APVMA-approved for listed uses. Use only on crops, pests and situations named on the label. This page does not authorise off-label use.

Dusk versus bees

Pyrethrins are dangerous to bees. The Py-Bo label says do not spray any plants in flower while bees are foraging. Citrus blossom is a bee crop. It is also where thrips and aphids feed. That overlap is why timing matters more than a daytime “quick knock” during bloom.

Apply after dark, when bees are in the hive. Residues continue to keep bees off treated surfaces into the next morning until UV degrades the pyrethrins (often around mid-morning). Do not treat Py-Bo as bee-safe in daylight on open flowers. A late-arvo or dusk application also hits pests that hide through the day, and it gives the spray the night before sunlight breaks it down.

Contact spray will also knock beneficials it hits (ladybirds, lacewings, hoverfly larvae, Orius, parasitoids). Because residues degrade in a few hours of UV, you can re-introduce beneficials onto a lower pest population once the pyrethrins are gone. Use Py-Bo as a knockdown or harvest-close flush, not as a weekly cover spray over an IPM program.

What Py-Bo will not do

Will not make an unlabelled pest legal. QFF, citrus leaf miner, citrus gall wasp, bronze orange bug, scales, mealybugs, mites, weevils and grasshoppers are not named horticultural pests on Py-Bo.
Will not kill Queensland fruit fly maggots inside fruit. Follow the mandated QFF program in your locality. Cutting a stung fruit: maggots mean fly; no grub means a bug sting or something else.
Will not kill citrus leaf miner larvae inside mines, or gall wasp larvae inside woody galls. Contact cannot reach them. Adult moths or wasps on the wing are not a registered Py-Bo claim.
Will not control bronze orange bug as a labelled use. It is a large sap-sucker on coastal citrus; it is not on the horticultural pest list. Do not stretch “bugs” on an old article into a claim.
Will not reliably control scales or mealybugs. Waxy coatings shed water-based contact sprays.
Will not kill thrips eggs in tissue, whitefly pupae, or aphids the spray never reaches (inside curled flush, the far side of the canopy, dry undersides).
Will not give a season-long residual. UV degrades pyrethrins; that is why WHP is one day.
Will not spare bees or beneficials it hits. Dusk, not daylight bloom.
Will not replace coverage. Contact product, contact required.

FAQ

Which citrus pests are on the Py-Bo label?

The horticultural pests named on APVMA 53738 are aphids, ants, cabbage moth and other caterpillars, earwigs, leafhoppers, thrips and whiteflies, on fruit and vegetable crops, cut flowers and ornamental plants. Citrus is fruit. Confirm the current label. This page is the hub for aphids, thrips, whiteflies and leafhoppers on citrus. It is not a claim for every insect that ever sat on an orange tree.

Will Py-Bo kill Queensland fruit fly, citrus leaf miner or citrus gall wasp?

No. Those pests are not on the Py-Bo horticultural list, and contact spray does not reach the damaging stages. QFF maggots are inside fruit. Leaf miner larvae are inside mines in young leaves. Gall wasp larvae are inside woody galls on twigs. Use the local QFF program for fruit fly, and other registered options or cultural controls for miner and gall wasp. That is a separate label decision — not Py-Bo.

What about bronze orange bug, scales and mites?

Bronze orange bug (Musgraveia sulciventris) is a large native shield bug on coastal citrus. It is not named on the Py-Bo horticultural pest list. Scales and mealybugs wear wax that sheds water-based contact sprays; they are not named either. Mites are not named. Do not treat an old “citrus pests” round-up as a registration.

What rate of Py-Bo, and what is the withholding period?

On the labelled horticultural use: 1 mL per 1 L of water (100 mL per 100 L). The withholding period on labelled edible plants is 1 day. Always confirm the crop, pest and WHP on the current APVMA-approved label. Do not invent rates.

When should I spray so I do not kill bees?

Do not spray any plants in flower while bees are foraging. Apply after dark when bees are in the hive. Residues keep bees off treated surfaces into the next morning until UV degrades the pyrethrins. Do not treat it as bee-safe in daylight on open citrus blossom — which is also when thrips and aphids are in the flowers.

Will one spray clean them up for the season?

No. Py-Bo is a contact knockdown with no residual. Aphids can rebuild in about a week. Thrips eggs in tissue and whitefly eggs on the underside survive the first pass. Missed undersides, curled flush and the far side of the tree keep live insects. Plan a follow-up when the next hatch is visible, often inside a week at peak, and keep walking flush, calyx and undersides.

Why are ants all over the citrus?

Honeydew. Aphids and whiteflies excrete it; ants farm it. Ants are on the Py-Bo horticultural list, so workers on the canopy can be knocked if the spray hits them. That does not treat the nest, and it does not replace covering the aphids and whiteflies that are making the honeydew.

Quick reference

Hub pests (on-label): citrus aphids, thrips (including Kelly’s citrus thrips), whiteflies; leafhoppers / citrus jassid if present
Also on the horticultural list: ants, cabbage moth and other caterpillars, earwigs
Aphids: black citrus aphid Toxoptera citricida (and other aphids) on flush; honeydew, ants, sooty mould; live young; generation ~1 week
Thrips: Kelly’s citrus thrips Pezothrips kellyanus — black adults, yellow-orange larvae; halo scarring and scurfing from petal fall to calyx closure; eggs in tissue
Whiteflies: Australian citrus whitefly Orchamoplatus citri (and other whiteflies) on undersides; honeydew and sooty mould; nymphs settle and go scale-like
Leafhoppers: Distantasca smithi — chlorotic distorted flush; oleocellosis-like spots on green fruit
Not claimed: QFF, citrus leaf miner, citrus gall wasp, bronze orange bug, scales, mealybugs, mites, weevils, grasshoppers
Spray: Py-Bo 1 mL/L or 100 mL/100 L; contact; 1-day WHP; tips, calyx, undersides; dusk vs bees; follow-up on hatch
Product: 80 g/L pyrethrins + 320 g/L PBO; APVMA 53738; fruit and vegetable crops, cut flowers and ornamental plants

Always read and follow the current APVMA-approved label. The label is the law. Py-Bo is available through Pestech Australia’s Ag resellers or direct.