Our site is currently being updated and pages are changing regularly. We thank you for your patience during this transition and hope that you find our new site easy to use.

Insect pest management in mungbeans

An image of

A crop of early podding mungbeans. Photo courtesy of H. Brier.

On this page:

Major pests of mungbeans:

Minor pests:

Insect pests can attack mungbeans at any stage from seedling to harvest but the crop is most susceptible from budding onwards. It is important to monitor crops once a week during vegetative growth as the first buds are borne below the top of the canopy.

Mungbeans can compensate for early damage by setting new buds and pods to replace those damaged by pests, however excessive early damage can delay harvest.

Seeds damaged by pod sucking bugs during early pod-fill are often lost at harvest, or are graded out post harvest, as they are markedly lighter than undamaged seeds.

However, seeds damaged from mid pod fill onwards are little different in weight to undamaged seeds and are not lost at harvest or able to be graded out without resorting to colour sorters.

Crops remain susceptible to late bug damage until the pods harden just prior to harvest. As a result, late bug damage is a major factor affecting seed quality. As a rule of thumb, only 2% seed damage is tolerable for mungbeans.

  • Mungbeans are not preferred hosts of silverleaf whitefly (SLW). While adults are often seen on mungbeans, the development of SLW nymphs is very poor in this crop.

Major pests of mungbeans


Helicoverpa can severely damage all crop stages and all plant parts of mungbeans. In sub-coastal and inland southern Queensland, summer legumes are at greatest risk from H. armigera from mid-December onwards. However, spring H. armigera outbreaks are more likely in coastal regions.


Larvae of helicoverpa can be confused with loopers, armyworms and cluster caterpillars. Refer to the A-Z pest list for identification of pests.


  • Helicoverpa defoliation is characterised by rounded chew marks and holes (loopers make angular holes).
  • High populations in seedling or drought-stressed crops can cause considerable damage if vegetative terminals and stems are eaten. This type of damage results in pods being set closer to the ground. Such pods are more difficult to harvest.
  • In drought-stressed crops, the last soft green tissue is usually the vegetative terminals, which are more likely to be totally consumed than in normally growing crops.
  • Once crops reach flowering, larvae focus on buds and flowers (vegetative terminals) before attacking pods. Small pods may be totally consumed by helicoverpa, but larvae target the seeds in large pods. Crops are better able to compensate for early pod damage, however in dry land crops, where water is limiting, significant early damage may delay or stagger podding with subsequent yield and quality losses.
  • Damage to well-developed pods also results in weather staining of uneaten seeds due to water entering the pods.


Beat sheet sampling is the preferred sampling method for medium to large helicoverpa larvae. Small larvae should be scouted for by inspecting (opening) vegetative terminals and flowers. Damage to vegetative terminals is often the first visual clue that helicoverpa larvae are present. Ideally, mungbeans should also be scouted for eggs and moths, to pinpoint the start of infestations and increase the chance of successful control.

  • Inspect crops weekly during the vegetative stage.
  • Inspect twice weekly from early budding until late podding.
  • Sample six widely-spaced locations per field.
  • Take five one-metre long samples at each site with a ´standard´ beat sheet.
  • Convert larval counts/metre to larvae/metre2 by dividing counts by the row spacing in metres.

Beat sheet sampling may only detect 50% of small larvae in vegetative and podding mungbeans, and 70% during flowering, as they feed in sheltered sites such as leaf terminals. However, many small larvae may be lost to natural mortality factors before they reach a damaging size and this cancels out sampling inefficiencies in most crops.


In general, mungbeans are more tolerant of early than late damage. Vegetative mungbeans can tolerate up to 33% defoliation without yield loss. While up to six helicoverpa/m2 have no impact on yield in well-watered flowering mungbeans, 35 kg/ha is lost/larva/m2 by late podding.

To simplify recommendations, the new reproductive threshold (late flowering/early podding to late pod-fill) is conservatively based on the rate of damage at late pod-fill, and varies from 1-3/m2, depending on the cost of control and the price of mungbeans. This threshold allows for possible yield loss in drought stressed crops damaged by helicoverpa at flowering.

Table 1: Economic threshold chart for helicoverpa in podding mungbeans, based on a measured yield loss of 35 kg/ha for every larva per m2. Cross-reference the cost of control versus the crop value to determine the economic threshold (ET), e.g. if the cost of control = $40/ha and the crop value =$600/t, the ET = 1.9. Spray helicoverpa only if they exceed the threshold which is the break even point
Cost of control# = value of damage ($/ha) Thresholds#(larve/m2) for conventional pesticides* at mungbean crop values listed below ($/t)
$350 $400 $450 $500 $550 $600 $650 $700 $750 $800
20 1.6 1.4 1.3 1.1 1.0 1.0 0.9 0.8 0.8 0.7
25 2.0 1.8 1.6 1.4 1.3 1.2 1.1 1.0 1.0 0.9
30 2.4 2.1 1.9 1.7 1.6 1.4 1.3 1.2 1.1 1.1
35 2.9 2.5 2.2 2.0 1.8 1.7 1.5 1.4 1.3 1.3
40 3.3 2.9 2.5 2.3 2.1 1.9 1.8 1.6 1.5 1.4
45 3.7 3.2 2.9 2.6 2.3 2.1 2.0 1.8 1.7 1.6
50 4.1 3.6 3.2 2.9 2.6 2.4 2.2 2.0 1.9 1.8
55 4.5 3.9 3.5 3.1 2.9 2.6 2.4 2.2 2.1 2.0
60 4.9 4.3 3.8 3.4 3.1 2.9 2.6 2.4 2.3 2.1
65 5.3 4.6 4.1 3.7 3.4 3.1 2.9 2.7 2.5 2.3

Chemical control

Prior to flowering, biopesticides (particularly Helicoverpa nucleopolyhedrovirus (NPV)) are recommended in preference to chemical insecticides. This helps conserve beneficial insects to buffer crops against helicoverpa attack during the susceptible reproductive stages, and avoids flaring of other pests such as mites.

Refer to: How to find the right insecticide for chemical control and current registrations.

For best results, all ingestion type products require thorough plant coverage. For biopesticides, addition of Amino Feed® or an equivalent product is recommended.

Cultural control:

  • Where possible, avoid successive plantings of summer legumes.
  • Good agronomy and soil moisture are crucial as large, vigorously growing plants suffer less defoliation for a given helicoverpa population and have less risk of terminal damage.
  • Vigorously growing plants with adequate available moisture are better able to replace damaged leaves and compensate for flower and pod damage.

Natural enemies

The combined action of a number of beneficial species is often required to have a significant impact on potentially damaging helicoverpa populations. It is therefore desirable to conserve as many beneficials as possible.

Natural enemies of mungbean pests include predators of eggs, larvae and pupae, parasites of eggs and larvae and caterpillar diseases.

Predatory bugs and beetles that attack helicoverpa eggs and larvae include:

Parasites include:

With the exception of Trichogramma and Microplitis, most parasites do not kill helicoverpa until they reach the pupal stage. Predatory earwigs and wireworm larvae are significant predators of helicoverpa pupae.

Naturally occurring caterpillar diseases frequently have a marked impact on helicoverpa in summer legumes. Outbreaks of NPV are frequently observed in crops with high helicoverpa populations.

Pod-sucking bugs

Pod-sucking bugs can move in at budding but significant damage is confined to pods. They start breeding as soon as they move in to flowering crops and nymphs must feed on pods to complete their development. Feeding by pod-sucking bugs causes shrivelled and distorted seed, and can severely reduce yield and seed quality. Pod-sucking bugs can even damage seeds in black pods that are nearing harvest maturity. Late bug damage reduces seed quality but not yield. As only 2% seed damage is tolerable in mungbeans, bug thresholds are based on seed quality, not yield.

A range of pod-sucking insects can attack mungbeans and include:

  • green vegetable bug
  • redbanded shield bug
  • large brown bean bug
  • small brown bean bug.

The green vegetable bug (GVB) and the brown bean bugs are equally damaging, while the damage potentials of the red-banded and brown shield bugs are 0.75 and 0.2 of that of a GVB respectively. Nymphs of all species are less damaging than adults. While first instar nymphs cause no damage, subsequent instars are progressively more damaging with the fifth and final instar being nearly as damaging as adults. To determine the damage potential of mixed bug species populations, convert all species (adults and nymphs) to GVB adult equivalents (GVBAEQ) .

Green vegetable bug (GVB) Nezara viridula

Pest status

This species is the most damaging pod-sucking bug in mungbeans due to its abundance, widespread distribution, rate of damage and rate of reproduction. Very high populations are frequently encountered in coastal Queensland.

Risk period

Adult bugs typically invade summer legumes at flowering, but GVB is primarily a pod feeder with a preference for pods with well-developed seeds. Mungbeans remain at risk until pods are too hard to damage (i.e. very close to harvest). Damaging populations are typically highest in late summer crops during late pod-fill (when nymphs have reached or are near adulthood).


Pods most at risk are those containing well-developed seeds. GVB also damages buds and flowers but mungbeans can compensate for this early damage. Damage to young pods causes deformed and shrivelled seeds and reduce yield. Seeds damaged in older pods are blemished, difficult to grade out and reduce quality.

Bug damaged seeds have increased protein content but a shorter storage life (due to increased rancidity). Bug damaged seeds are frequently discoloured, either directly as a result of tissue breakdown or water which may gain entry where pods are pierced by bugs.

Sampling and monitoring

Crops should be inspected for GVB twice weekly from budding until close to harvest.

  • Sample for GVB in early to mid morning.
  • Beat sheet sampling is the most efficient monitoring method.
  • Standard sampling units consist of five one-metre non-consecutive lengths of row within a 20 m radius.
  • Convert all bug counts/row metre to bugs/m2 by dividing counts/row metre by the row spacing in metres.
  • At least six sites should be sampled throughout a crop to accurately determine adult GVB populations.
  • GVB nymphs are more difficult to sample accurately as their distribution is extremely clumped, particularly during the early nymphal stages (instars 1-3).
  • Ideally, at least 10 sites (with five non-consecutive row metres sampled/site) should be sampled to adequately assess nymphal populations.


Podsucking bug thresholds in mungbeans are determined by seed quality, the maximum bug damage permitted being only 2%. GVB thresholds typically range from 0.3-0.6/m2 depending on the crop size (seeds/m2). Because thresholds are determined by % damage, the larger a crop (the more seeds per unit area), the more bugs that are required to inflict critical (threshold) damage, and the higher the threshold. See table below:

Days to harvest maturity* Crop size (seeds/m)
500 1000 1500 2000 2500 3000 3500 4000 4500 5000
21 0.20 0.40 0.61 0.83 1.05 1.28 1.52 1.77 2.02 2.28
28 0.15 0.30 0.46 0.62 0.79 0.96 1.14 1.33 1.52 1.71
35 0.12 0.24 0.36 0.50 0.63 0.77 0.91 1.06 1.21 1.37

In practice in infested crops, GVB and other pod-sucking bugs are usually present from 28-35 days prior to harvest, and populations increase rapidly as a result of in-crop breeding.

Chemical control:

  • Bugs should be controlled during early pod-fill before nymphs reach a damaging size.
  • Pesticides are best applied in the early to mid morning to contact bugs basking at the top of the canopy.
  • See: How to find the right insecticide .

Cultural control:

  • Avoid sequential plantings of summer legumes as bug populations will move progressively from earlier to later plantings, eventually building to very high levels.
  • Also avoid cultivar and planting time combinations that are more likely to lengthen the duration of flowering and podding.

Natural enemies:

  • GVB eggs are frequently parasitised by a tiny introduced wasp Trissolcus basalis . Parasitised eggs are easily recognised as they turn black.
  • GVB nymphs are attacked by ants, spiders and predatory bugs.
  • Final (fifth) instar and adult GVB are parasitised by the recently introduced tachinid fly Trichopoda giacomellii which occurs in south Queensland coastal regions.

Redbanded shield bug (RBSB) Piezodorus oceanicus

Redbanded shield bugs in Australia have been previously classified as Piezodorus hybneri and P. grossi.

Pest status

Major, widespread, regular. RBSB is 75% as damaging as GVB in summer pulses but is usually not as abundant. However, it is more difficult to control with current pesticides. Adults are similar in shape to GVB but are smaller and paler, with pink, white or yellow bands.


Damage is similar to that caused by GVB, with early damage reducing yields, and later damage reducing the quality of harvested seeds.


Convert to GVB equivalents to determine damage potential. For further information see: Converting pod sucking bugs to green vegetable bug equivalents (GVBEQ) and green vegetable bug adult equivalents (GVBAEQ) .


As for GVB. Beat sheeting is the preferred sampling method. Look for the distinctive twin-row egg rafts which indicate the presence of RBSB.

Chemical control

No insecticides are specifically registered against RBSB in Australia. Recent trials suggest pesticides currently registered against GVB are ineffective against RBSB. However, control can be improved, albeit to only 50-60%, with the addition of a 0.5% salt (NaCl) adjuvant.

Natural enemies

Spiders, ants, and predatory bugs are major predators of RBSB, particularly of eggs and young nymphs with mortality of these stages sometimes exceeding 90%. Eggs may be parasitised by the tiny wasp, Trissolcus basalis. Adults are infrequently parasitised by the recently introduced tachinid fly, Trichopoda giamocellii.

Pest status

As damaging as GVB. More frequent on the coast.

Risk period

As for GVB.


Both large and small brown bean bugs are as damaging as GVB. Damage is similar to that caused by GVB, with early damage reducing yield, while later damage reduces the quality of harvested seed.


Sample crops early in the morning. The beat sheet method is not totally satisfactory as both brown bean bugs are very flighty, particularly during the hotter parts of the day. Crop scouts should familiarise themselves with the appearance of flying brown bean bug adults and include these in sampling counts.


Mirids target buds and flowers causing them to abort and are considered one of the key pests of mungbeans. Mirids can be at the budding threshold prior to budding, so it is very important to scout weekly prior to budding, and not to miss the start of budding.

Risk period and damage:

  • Budding, flowering and early-podding crops are at greatest risk.
  • Low populations (one or less per m2) of green mirids are often present in vegetative crops but there is no evidence they cause ´tipping´ of vegetative terminals or yield loss.
  • Influxes of mirid adults often follow northwest winds in spring.


  • Mirids are very mobile and in-crop populations can increase rapidly.
  • Crops should be inspected twice weekly from budding onwards until post flowering.
  • In row crops, the preferred method is beat sheeting, as this method is the most effective for helicoverpa and pod-sucking bugs.
  • Sample five one-metre lengths of row (not consecutive) within a 20 m radius, from at least six sites throughout a crop.
  • Avoid sampling during very windy weather as mirids are easily blown off the sheet.
  • Thresholds for mirids in mungbeans vary from 0.3-0.6/m2, depending on application costs and mungbean prices.


  • Shortening a crop´s flowering period reduces the risk of mirid damage.
  • Flowering periods can be shortened by planting on a full moisture profile and by watering crops just before budding.
  • Consider planting crops in at least 50 cm rows (as opposed to broadcast planting) to facilitate easier pest sampling.
  • Trials have shown that the addition of salt (0.5% NaCl) as an adjuvant can improve chemical control of mirids at lower chemical rates. Reducing pesticide rates (typically by 50-60%) greatly reduces their impact on beneficials and reduces the risk of flaring helicoverpa.
  • For chemical control, see How to find the right insecticide .

Natural enemies

Spiders, ants, predatory bugs and predatory wasps have been observed attacking mirids in the field. Naturally occurring fungi (e.g. Beauvaria ) may also infect and kill mirids, but are rarely observed in the field.

Bean podborer

Maruca vitrata


  • Crops may be infested from early budding onwards.
  • Eggs are laid on or in the flowers (inserted between the petals). Young larvae feed inside the flowers before moving to developing pods when mid-sized.
  • Seeds in damaged pods are totally or partially eaten out by larvae.
  • Entry holes also let in water, which stains the remaining non-eaten seeds.
  • Early sign of infestation is the webbing of flowers.
  • Infested pods have a well-defined entry hole (usually one/larva), frequently ringed with larval frass.

Monitoring and control:

  • Open all flowers from as many racemes as possible to look for larvae (at least 30 racemes randomly sampled across a crop).
  • Divide the total number of BPB detected by the number of racemes sampled, and multiply by the estimated number of racemes/m2.
  • Current threshold are 3 larvae/m2 but accurate assessments are difficult where larvae are inside flowers or pods.
  • Pesticides are most effective if applied before larvae enter pods.
  • For chemical control and current registrations - How to find the right insecticide .

Minor pests

Cluster caterpillar

Spodoptera litura (often referred to as ´spods´).

Pest status and damage:

  • As damaging as helicoverpa but less frequent.
  • Can cause significant damage to mungbeans in Queensland during flowering and podding.
  • Small larvae window leaves, but older larvae chew holes in leaves.
  • Older larvae may also attack flowers and pods.

Monitoring and control:

  • As for helicoverpa.
  • Look also for egg masses and clusters of young larvae.
  • In pre-flowering crops, control is warranted if defoliation exceeds (or is likely to) exceed 33%.
  • Tolerable defoliation drops to 15-20% once flowering and podding commences.
  • Cluster caterpillars are not controlled by NPV products and are difficult to control with Bt (Bacillus thuringiensis ) unless very small.

Natural enemies

As for helicoverpa and loopers.


Etiella behrii (lucerne seed web moth)

Risk period and damage:

  • Crops may be infested from flowering onwards, but are at greatest risk during late podding.
  • Because etiella larvae consume far less than larger caterpillar species such as Helicoverpa, seeds are often only partially eaten out, often with characteristic pin-hole damage.
  • This damage is difficult to grade out and its unattractive appearance reduces seed quality.
  • The pale frass excreted by these caterpillars inside damaged pods is often mistaken for bruchid eggs.

Monitoring and control

Techniques are being developed to monitor moth activity with light traps or lures, as the moth is this pest´s most vulnerable stage. No pesticides are currently registered.


Green loopers:

Brown loopers:

The following apply equally to green and brown coloured loopers.

Risk period and damage:

  • Crops can be attacked at any stage but are at greatest risk during flowering and podding.
  • Summer legumes are least tolerant of defoliation at these stages.
  • Loopers can attack the flowers and small pods of mungbeans.
  • Looper leaf damage is different to helicoverpa damage, the feeding holes being more angular rather than rounded.

Monitoring and control:

  • Use a beat sheet .
  • Inspect crops weekly during the vegetative stage and twice weekly from very early budding onwards until crops are no longer susceptible to attack.
  • In pre-flowering crops, looper control is warranted if defoliation exceeds (or is likely to) exceed 33%. Tolerable defoliation drops to 15-20% once flowering and podding commences.
  • Loopers are not controlled by products containing Helicoverpa NPV.
  • Small loopers (under 12 mm long) can be controlled with Bt.
  • For chemical control options - How to find the right insecticide .

Natural enemies:

  • Loopers are frequently parasitised by braconid wasps (Cotesia sp.) with scores of parasite larva developing/looper host.
  • Predatory bugs, tachinid flies, and ichneumonid wasps also attack loopers.
  • The use of Bt will help preserve beneficial insects.
  • Outbreaks of looper NPV are frequently observed in crops with high looper populations. However, larvae are usually not killed by virus until they are medium-large (instars 4-5). Looper virus is not the same as Helicoverpa NPV.

Bean fly

Ophiomyia phaseoli

Risk period and damage:

  • Crops are at greatest risk for three to four weeks from emergence, but later crops are sometimes attacked.
  • Larval tunnelling damages the plant´s vascular tissue, causing seedling death, reduced plant vigour and petiole droop in older crops.
  • Crops in coastal and sub-coastal regions are at greatest risk.

Monitoring and control:

  • Monitor seedling crops twice weekly.
  • Look for the distinctive pale oviposition pinprick windows in the leaves and for larval tunnelling at the base of petioles and in the stems.
  • Look for pupae and damaged stem tissue in the lower stems.
  • Also look for adult flies.
  • Take action if more than one larval tunnel/plant.
  • Control is readily achieved in young crops with systemic pesticides, but repeat sprays (within seven days) may be required for heavy infestations.
  • Sprays against beanfly in mature crops may not be cost effective.
  • Ensure cropping areas are free of weed hosts such as phasey bean and volunteer crop legumes.
  • For chemical control - How to find the right insecticide .

Cowpea aphid

Aphis craccivora

Pest status

Moderate, widespread, and irregular. Cowpea aphids attack many legumes, cotton and lettuce and find mungbeans particularly attractive hosts.

Risk period and damage:

  • Mungbeans are susceptible from flowering onwards.
  • Later-season crops are at greater risk than spring planted crops.
  • Cowpea aphids inject toxins into the plant while feeding.
  • Severe infestations most likely reduce mungbean vigour and yield.
  • Aphid feeding produces honeydew making harvesting difficult.
  • Honeydew produced by aphids promotes sooty mould which reduces photosynthesis.

Monitoring, thresholds and control:

  • The presence of ladybirds, hoverflies and smudge bugs are often an indication that aphids are present.
  • Look for aphid colonies on plant stems by parting the canopy.
  • Heavy aphid infestations will become readily visible when they spread to the upper leaves and pods.
  • There are no set thresholds for cowpea aphid in mungbeans.
  • For chemical control see How to find the right insecticide .

Natural enemies

Ladybirds, predatory bugs and hoverfly larvae are key predators. Avoid early ´hard´ sprays so predators can keep aphids in check.

Cotton seedling or cereal thrips Thrips tabaci

Risk period and damage:

  • Spring planted crops are at greatest risk, especially those in close proximity to maturing cereal crops.
  • The peak infestation risk period is seedling emergence. Thrips attack the seedling´s growing point and damage the embryonic leaves.
  • Damage is not manifested until the first trifoliate leaves open and is not evident in the unifoliate leaves.
  • Damaged leaves can be severely distorted and discoloured.
  • Damaged plants are stunted and resemble herbicide (2-4D) damage.
  • Vigorously-growing crops quickly out-grow the symptoms but slowly growing plants seemingly take a considerable time to recover. However, this is more likely due to low spring temperatures (<18°C) slowing plant growth rather than thrips damage.
  • In two field trials, seedling thrips had no effect on yield or plant maturity (i.e. on time to flowering or harvest), despite trial seedlings displaying severe leaf distortion.

Monitoring, thresholds and control:

  • Open and microscopically examine the plant´s growing point for thrips.
  • Plucked growing points can also be dunked in alcohol or thrips solution to dislodge thrips.
  • There are no thresholds for seedling thrips and it is unlikely that this pest reduces mungbean yields except under extreme circumstances.
  • No seed dressings are currently registered for thrips control in mungbeans. Seed dressings tested to date reduce root nodulation by 60%.
  • While chemical control is rarely warranted, for options refer to chemical control link.
  • If possible, do not plant mungbeans immediately adjacent to winter cereals.Avoid spring mungbean plantings in regions where cool spring weather is likely, as this has greater impact on mungbean growth than seedling thrips.

Natural enemies

If a decision is made to control thrips, apply a narrow band spray over the seedlings to preserve predators such as spiders in the inter-row.

Flower thrips

Pest status:

  • Pest status is moderate, widespread and regular.
  • Pest status is likely to increase given that they are vectors of the Tobacco Streak Virus (TSV) which also affects mungbeans.

Risk period and damage:

  • Crops are at greatest risk during flowering and podset.
  • Early infestations increase the risk of TSV.
  • Nymphs and adults feed in growing points and inside flowers which can result in flower abortion and pod distortion.
  • Deformed pods may be difficult to thresh, resulting in further yield losses.

Monitoring, thresholds and control:

  • Open and examine flowers for thrips.
  • If flowers cannot be assessed immediately, store in 70% alcohol to dislodge thrips and prevent thrips escaping.
  • Control thrips if on average more than 4-6 thrips/flower.
  • For chemical control options refer to How to find the right insecticide .
  • Vigorously growing crops can better compensate for flower abortion.
  • Remove weeds such as Parthenium which host TSV. These weeds are also a potential source of infested pollen which can be blown into mungbean crops.

Natural enemies

Pirate bugs, lacewing larvae and ladybirds prey on thrips. Thrips themselves are thought to be important mite predators.

Cowpea bruchid Callosobruchus maculatus

Pest status

Bruchids can become a major storage pest when best-practice post-harvest storage practices are not adhered to. Mungbeans are often infested in the field but infestations are often not detected until three or more months post harvest. Infestations can also be initiated post harvest where harvesting equipment and storage facilities are not regularly cleaned to remove old seed (a major risk factor). Bagged planting seed kept for any length of time out of cold storage is at particular risk.


  • Clean out all storages, field bins, trucks and harvesters before harvest.
  • Ensure silos are airtight for effective fumigation, should that be necessary.
  • Keep bagged planting seed in cold rooms wherever possible, particularly if it is to be held for any length of time.
  • More information about bruchids - grain storage and fumigation .

Further information

Last updated 30 July 2012