Australian Mungbean Association

Australian-grown mungbeans have quality written all over them!

Managing insect pests in mungbean

Insect pests can significantly reduce the profitability of mungbean, through reduced yield and seed quality. Accordingly, insect damage is one of the main reasons for downgrading mungbeans.

Crops should be inspected at least weekly during the vegetative stages and twice weekly from budding onwards (depending on pest pressure). While early damage is less likely, high pest pressure in seedling/early vegetative crops can severely reduce yield potential.

The onset of budding marks a critical stage when the crop becomes more attractive to major pests including mirids, helicoverpa and bean podborer. Mungbeans are at greatest risk from pod-sucking bugs from early podfill until late pod ripening.

Crops not converting buds/flowers to pods may contain damaging pest numbers, which are aborting or eating these structures before they progress to pods. However heat and moisture stress can also abort buds and flowers. It cannot be automatically assumed therefore that pests are to blame for poor pod set.

Mungbeans can compensate for moderate early damage by retaining undamaged buds and flowers that otherwise might be shed naturally. Under favourable growing conditions, they can even compensate for severe early damage by setting new buds and pods. However this can result in uneven and delayed harvest maturity. In addition, their compensatory ability is reduced if there is ongoing significant pest pressure.

The main insect pests of mungbean are helicoverpa, mirids, green vegetable bug, red-banded shield bug, large and small brown bean bugs, bean podporer and thrips.



(Helicoverpa armigera, Helicoverpa punctigera)

Pest status: Helicoverpa are major mungbean pests. They can attack at any stage from seedlings to late podfill but mungbeans are most attractive to helicoverpa from budding onwards. The more difficult-to-control H. armigera predominates in summer crops, but check larvae in all crops as H. armigera can be the dominant species at any time of the year.

Damage: Helicoverpa can attack all above-ground parts of the mungbean plant. High populations can severely damage seeding and young vegetative crops, especially if they are drought stressed. In these situations, larvae feed more on the plant’s terminals and axillary buds (the precursors to floral buds), and less on the leaves themselves.

Once crops reach flowering, larvae focus on buds, flowers and pods. Small pods may be totally consumed, but larvae target the seeds in large pods. Crops are better able to compensate for early than late pod damage. However in dryland 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.

Monitoring: 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 and buds are often the first visual clues 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 twice weekly at all stages.
  • Sample 6 widely spaced locations per field.
  • Take 5 one-metre long samples at each site with a ‘standard’ beat sheet.
  • Convert larval counts/metre to larvae/m2 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.


Vegetative crops: A new provisional threshold of 4–5 larvae/m2 has been set for mid to late vegetative crops with good soil moisture, and is based on data from soybeans. Lower the threshold in seedling and small vegetative crops, particularly if soil moisture is limited. Take action if larvae are targeting buds and terminals rather than leaves.

Budding/flowering/podding: Thresholds are tabled below. For current (2010) crop values, the threshold is approximately 2 larvae/m2, but can potentially vary between 1 and 3 larvae/m2, depending on control costs and crop values.

Green and brown mirids

Green mirid (Creontiades dilutus) and brown mirid (Creontiades pacificus)

Pest status: Mirids target buds and flowers causing them to abort and are one of the key pests of mungbeans. Mirid populations can gradually build up in vegetative crops and may be above the flowering threshold before budding, but have no impact on yield at this stage. It is critical to scout crops regularly to pick the start of budding as this is a critical stage for mirids and other key pests.

Risk period and damage: Budding, flowering and early-podding crops are at greatest risk.

  • Mirids attack buds, flowers and small pods.
  • There is no evidence mirids cause ‘tipping’ of terminals or yield loss in vegetative crops.
  • Influxes of mirid adults often follow north-west winds in spring.
  • Mirids are very damaging because they are typically present in crops in increasing numbers for 3–4 weeks from early budding.


  • Crops should be inspected twice weekly from budding onwards until post-flowering.
  • Mirids are very mobile and in-crop populations can increase rapidly.
  • In row crops, the preferred method is beat sheeting, as this method is also the most effective for helicoverpa and pod-sucking bugs.
  • Sample 5 one-metre lengths of row (not consecutive) within a 20 m radius, from at least 6 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.

Thresholds: 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).
  • DAF trials show that the addition of salt (0.5% NaCl) as an adjuvant can improve mirid control at lower pesticide rates. Reducing dimethoate rates (typically by 50%) greatly reduces their impact on beneficial insects and also the risk of flaring helicoverpa. While even lower reductions are possible (e.g. by 66%), very low rates have insufficient residual activity to control hatching nymphs and should be avoided if there is high mirid pressure.
  • The efficacy of dimethoate, the preferred mirid pesticide, is greatly reduced in alkaline water, so always add a buffer such as Li700 if necessary.


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 crops.

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 podfill (when nymphs have reached or are near adulthood).

Damage: 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 reduces yield.

Seeds damaged in older pods are blemished, difficult to grade out and reduce grain quality. Bug-damaged seeds are frequently discoloured, either as a direct result of tissue breakdown or water that may gain entry where pods are pierced by bugs.

Sampling and monitoring: Inspect crops for GVB twice weekly from flowering until close to harvest.

  • Sample for GVB in early to mid morning.
  • Beat sheet sampling is the most efficient monitoring method.
  • Sample 5 one-metre non-consecutive lengths of row within a 20 m radius. This constitutes one (1) sample site.
  • Sample at least 6 sites throughout a crop to accurately determine GVB populations.
  • Convert your bug counts/row metre to bugs/m² by dividing counts/row metre by the row spacing in metres.

Thresholds: Pod-sucking bug (PSB) thresholds in mungbeans are determined by seed quality, the maximum bug damage permitted being only 2%. PSB thresholds are expressed in GVB adult equivalents/m². The damage potential of PSB in your crop is most easily calculated using DAF’s online economic threshold calculator on The Beatsheet Blog. Simply select the 'Economic Thresholds Calculator' option and enter the crop type (mungbeans), the predicted yield (t/ha), your row spacing (metres) and the average PSB counts as sampled with a standard beat sheet.  Enter the number of and stages of all PSB species present and the calculator will calculate the damage potential of all PSB in your crop, and will compare it with the threshold.

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.

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.

Redbanded shield bug (RBSB)

(Piezodorus oceanicus)

Redbanded shield bug in Australia was previously classified as Piezodorus hybneri and more recently as P. grossi. Despite its name, only the females have red bands, the males having pale cream bands.

Pest status: Redbanded shield bug is a major mungbean pest. While normally not as abundant as GVB, it is nearly as damaging, and is far more difficult to kill with current pesticides. When spraying for this pest, always add a 0.5% (w:v) salt (NaCl) adjuvant to give better control.

Damage: Damage is similar to that caused by GVB, with early damage reducing yield, and later damage reducing grain quality.

Thresholds: Convert your redbanded shield bug counts to GVB equivalents to determine their damage potential. Do this by multiplying them by 0.75. If GVB are also present, total the two counts (plus those of any other pod-sucking bug species) to determine the damage potential of all the podsucking bugs present in your crop. An online calculator for podsucking bug thresholds is available on The Beatsheet website.

Monitoring: As for GVB. Beat sheeting is the preferred sampling method. Look for the distinctive dark twin-row egg rafts, which indicate the presence of egg-laying RBSB adults.


Large brown bean bug and small brown bean bug

(Riptortus serripes) and (Melanacanthus scutellaris)

Pest status: As damaging as GVB. Frequently found in mungbeans, but more frequent on the coast. Harder to sample than GVB as the adults are very flighty, and the nymphs look like ants.

Risk period: As for GVB.

Damage: Both large and small brown bean bugs are equally damaging and 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. An online calculator for podsucking bug thresholds is available on The Beatsheet Blog.


Bean podborer

(Maruca vitrata) (previously Maruca testulalis)

Pest status: A major pest in coastal and tropical regions.


  • Bean podborer Infests crops 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 eaten out by larvae.
  • Entry holes also let in water, which stains the remaining seeds.
  • An early infestation sign is webbing of flowers.
  • Infested pods have a well-defined entry hole (usually one/larva), frequently ringed with 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 bean podborers 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 feeding inside flowers or pods.
  • Pesticides are most effective if applied before larvae enter pods.



Pest status: Thrips are widespread and regular pests of mungbeans. While they are key vectors of Tobacco Streak Virus (TSV), trying to control thrips is not an effective TSV management strategy. The best TSV strategy is to eradicate all weeds hosting TSV adjacent to the crop.

Damage—flower thrips:

  • Crops are at greatest risk during flowering and podset.
  • 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.

Damage—seedling thrips:

  • Spring crops adjacent to cereals are at greatest risk of infestation.
  • Plants are infested as they are emerging from the soil.
  • Despite the alarming symptoms, seedling thrips rarely have any impact on crop yield or time to harvest.
  • In cool weather, low temperatures rather than thrips are responsible for poor plant growth.
  • Spraying seedling thrips after the symptoms become apparent is mostly a waste of time.

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 are found.
  • Vigorously growing crops can better compensate for flower abortion.
  • Remove weeds such as parthenium that host TSV. These weeds are also a potential source of infested pollen that can be blown into mungbean crops.

For more information: Managing TSV risk in Mungbean crops


Silverleaf whitefly (SLW)

Mungbeans are not a preferred host of silverleaf whitefly. While adults are often seen on mungbeans, SLW nymphs only develop poorly. However, SLW would pose a threat if the destructive mungbean yellow mosaic virus (YMV) gained entry into Australia as SLW are a key vector of YMV, and very few SLW are required to transmit the disease.



(Ophiomyia phaseolus)

Pest status:  An increasingly serious pest of seedling crops in coastal and tropical regions such as the Burdekin.  Rarely a problem in traditional more inland mungbean-growing regions west of the Great Dividing Range.


Helicoverpa larvae feeding on an adzuki pod.

Green mirid adult.

Green vegetable bug (GVB) adult.

Redbanded shield bug (RBSB) adult.

Brown bean bug adult.

Thrips in bean flower.

Bean podborer in adzuki pod.