PestFacts June 2022
Pests to look out for in emerging crops
As crops emerge, a range of invertebrates also become active. Young crops are particularly susceptible to feeding damage for the first 3 to 5 weeks following emergence. Where possible, use agronomic practices to ensure rapid crop establishment, after which crops can often withstand moderate damage.
Regularly monitor crops to ensure early detection and correct identification will allow you to select appropriate controls. Do not to assume that pre- and post-emergent insecticides will adequately control pest issues – different pests require specific management, and monitoring is the only way to be sure!
Many potential pests are active at night, so get your headlamp out and go for an evening stroll!
Earth mites
At least four earth mite groups feed on seedling crops. Correct earth mite identification, using the Crop Mites Back Pocket Guide, is crucial for effective control; different mite species vary in susceptibility to insecticide, either naturally or through insecticide resistance.
Hatching of redlegged earth mite () (RLEM; Haylotydeus destructor) follows autumn rainfall (>5 mm) and cool temperatures (range <16°C to <20.5°C). SARDI entomologists report no hatching as of 20 May 2022 on the Yorke Peninsula, but mites are now hatching at the Waite. RLEM often gather in groups of 30 or more when feeding. Resistance to synthetic pyrethroid and organophosphate insecticides has been detected in RLEM around the Upper South East and Fleurieu Peninsula regions. To help manage resistance, see the GRDC resistance management strategy for RLEM.
Blue oat mites () (BOM; Penthaleus spp.) are similar in appearance to RLEM but have a distinct orange-red patch on their back that is visible under a hand lens. Unlike RLEM, BOM typically feed singularly or in small groups.
Bryobia mites () (Bryobia spp.), or clover mites, are relatively small mites with a flattened body, and front legs up to 1.5 times their body length. They prefer warmer conditions and are often seen earlier in autumn than other species. If treatment is necessary, organophosphates may provide better control than synthetic pyrethroids. Populations decline during cold winter conditions.
Balaustium mites () (Balaustium medicagoense) are relatively large, slow-moving mites often observed feeding at the tips of leaves. Pyrinex Super® is the only registered product for this species (and only in canola).
Springtails
Lucerne flea () (Sminthurus viridis) hatch following adequate rainfall. We have not received any reports this season. Lucerne flea feeds on a range of crops and pastures, causing a characteristic ‘windowing’ of leaves. Lucerne flea occurs in hotspots in paddocks, so it is important to monitor paddocks entirely. If treatment is necessary, avoid synthetic pyrethroids; organophosphates are recommended. Pitfall traps collected at the ‘CAUGHT RED HANDED’ SAGIT trial sites have been examined by SARDI entomologists, with some lucerne fleas identified, but none feeding.
Other springtails that can be found in broadacre winter crop are most likely beneficials that consume decaying vegetation or fungi and play an important ecological role in the decomposition process. A commonly reported species purple scum collembola (Hypogastura vernalis) is often seen in very large numbers rafting on puddles during wet conditions (read more: PestFacts SA Issue 4: Springtails: friend or foe?).
Beetles and weevils
The larvae and adults of several beetle species can be infrequent pests of seedling crops in autumn. Look out for the following species: Mandalotus weevils () (Mandalotus spp.) are native Australian weevils, with at least 10 species, known to feed on crops in parts of south-east Australia. Adults have been seen damaging canola at Mount Hope. Adults are 3 to 5mm long and emerge onto the soil surface during late autumn. They are often difficult to find; search at night using a torch, or during the day in the top 1 cm of soil at the base of weeds or damaged seedlings. Adults lop stems, cotyledons or seedlings. In canola, check problem areas (history of Mandalotus damage) for damage one week after emergence. If needed, insecticidal spot treatment to control adults is the only management option. For more information see the SARDI Mandalotus weevils in canola factsheet ().
The vegetable weevil () (Listroderes difficilis) is an infrequent sporadic pest widespread in cropping areas. Adults and larvae feed on foliage at night during early winter. Adults are 8 mm long with grey-brown bodies, a prominent weevil snout and a distinctive pale-coloured ‘V’ on their back. Larvae are legless, yellow to green in colour with an orange-brown head. Check emerging canola crops for feeding damage and weevils along crop edges or near areas with host weeds, particularly capeweed.
Larvae of the southern false wireworm (), or vegetable beetle (Gonocephalum spp.) are minor pests of winter cereals and canola. They mainly feed on decaying plant matter but sometimes larvae can feed on germinating seeds underground, while adults can feed on emerging canola at ground level. Larvae are cream, yellow or tan with cylindrical elongate bodies. Adults are small, matte dark grey-black coloured beetles. Low numbers of vegetable larvae and adults have been reported at Frances alongside high numbers of carabid beetles (predatory beneficial insects).
Larvae of bronzed field beetle () (Adelium brevicorne) are often active in autumn, and attack canola at ground level, causing seedling losses. Removal of surface trash is an effective management strategy for this pest in problem areas. Adults are shiny black beetles up to 11 mm long with a slight bronzed colour. Larvae are up to 12 mm in length, dark and shiny with two upturned spines at the tail end. Larvae in very low numbers have been detected in some pitfall traps in chaff lines.
Earwigs, millipedes and slaters
The black Portuguese millipede () (Ommatoiulus moreletti) and slaters () are primarily detritus feeders; in recent years, higher densities of these invertebrates have been associated with crop damage. In particular, the pill bug, Armadillidium vulgare, has damaged lentils and canola; this slater species rolls into a ball and can reach extremely high densities. Other slater species are often present in paddocks and are unlikely to cause damage.
The European earwig () (Forficula auricularia) is a infrequent sporadic pest of broad-acre crops, and generally most abundant when paddocks provide adequate habitat for population growth. Removal of trash and reducing stubble retention is the main form of control. There are no registered insecticides for European earwig; methiocarb snail baits and fipronil-based seed treatments may offer some control but may not protect seedlings against high densities.
How to report
PestFacts SA wants to know what you find in your crops and pastures, whether it’s a pest, beneficial or unknown – and even the 'usual' pests. Reports of not finding anything are valuable too.
Please send your reports or identification requests via the PestFacts map online report form or contact:
Rebecca Hamdorf
M: 0429 547 413
T: 8429 0682
E: rebecca.hamdorf@sa.gov.au
Maarten van Helden
M: 0481 544 429
T: 8429 0642
E: maarten.vanhelden@sa.gov.au
Catching crop thieves red-handed
The next round of the SAGIT funded research project called ‘CAUGHT RED HANDED’ (see PestFacts June 2021: Crop thieves caught red-handed for earlier project updates) has begun with cameras and traps installed in three low-rainfall paddocks pre-sowing. We’re aiming for paddocks that were reported having damage by slaters or millipedes to confirm the culprits.
Recent camera activity
Pre-sowing seedlings of broadacre crops (canola, chickpea, lentil, wheat, vetch, barley and faba bean) have been planted in front of infrared cameras to catch nocturnal activity and feeding.
The main culprits caught feeding on the seedlings so far include mice (all crops) and siton weevils (), (mainly on vetch and lentils), and some Egyptian beetle (Blaps blaps) feeding on canola. We are also seeing lots of predatory invertebrates active.
Recent pitfall trap catches
Alongside the cameras, multiple pitfall traps have been set up. These traps have shown a different insect profile to the camera traps, including activity of ants, slaters, and millipedes. This shows the value of catching feeding behaviour as it happens to correctly identify what is feeding on crops.
The infrared cameras are giving us unique insight into night-time feeding damage, which is not possible with the eye alone. With this system we have been able to identify the culprits of early crop damage, which in the past has been difficult to catch as it happens.
Camera and traps have now been set up after sowing and results will arrive over the next few months.
For more detail, contact:
Maarten van Helden
M: 0481 544 429
T: 8429 0642
E: maarten.vanhelden@sa.gov.au
Current iMapPESTS observations
As part of the iMapPESTS project, we are recording winged aphid and beneficial invertebrate captures at Frances and Giles Corner, Riverton (just north of Tarlee) in the high suction trap.
Frances: Sentinel 7
The most recent samples from Sentinel 7 at Frances had very low numbers of any invertebrates, with several days of no capture. A total of three oat aphids () (Rhopalosiphum padi), were caught, with spiders and a range of species of parasitoid wasps commonly found.
The previous two weeks also saw low numbers of all invertebrates, with total numbers decreasing as May got colder. Early May saw only one of each oat aphid and corn aphid () (Rhopalosiphum maidis) caught, and low numbers (1 to 2 every several days) of Rutherglen bug () (Nysius vinitor). Spiders and parasitoid wasps are captured in the sentinels consistently, with a variety of species seen.
Giles Corner: Sentinel 1
Sentinel 1 at Giles Corner (mid-north high rainfall zone) has had very low captures generally, and no broadacre pest aphids have been recorded in May. A total of four Rutherglen bugs have been caught for the entire month. As with sentinel 7, a diverse range of species of spiders and parasitoid wasps are consistently caught, with several nabids also recorded.
What the recent iMapPESTS data means
Migration of grains broadacre aphids in these regions are currently very low to non-existent. While January saw much higher-than-average rainfall, the rest of summer and start of autumn have not been as wet, particularly in the regions the sentinels are placed. This suggests that the risk of green bridge is not as high as originally suspected.
The consistency of finding a range of beneficials, particularly spiders and parasitoid wasps, suggests they are present in the landscape and populations are available to build up if pest numbers increase.
The sentinel is a singular sampling point in one location with a focus on flying (or ballooning) invertebrates, so don’t forget to monitor your own paddocks to get an idea of what’s happening on your property.
No results were found
PestFacts needs you
Your reports of invertebrate activity in broadacre cropping are vital in keeping PestFacts SA up-to-date and relevant. SARDI entomologists are currently traveling across the state undertaking several research projects but can’t be everywhere at once. We’re interested in hearing, not only about unusual pest reports, but the activity of common pests or even when there has been no activity.
Don’t forget – PestFacts SA offers free identification of invertebrate pests to subscribers! See What insect is that? How to have insects identified for free for more information.
Contact PestFacts SA
You can email, ring or text the PestFacts SA coordinators directly:
Rebecca Hamdorf
M: 0429 547 413
T: (08) 8429 0682
E: rebecca.hamdorf@sa.gov.au
Maarten van Helden
M: 0481 544 429
T: (08) 8429 0642
E: maarten.vanhelden@sa.gov.au
You can also contact PestFacts SA on Twitter @PestFactsSARDI or use the #PestFactsSA hashtag.
PestFacts map
Not only can you view historical pest records from South Australia and Victoria on the PestFacts map, you can also send reports. SARDI entomologists will receive your report by email and will follow up with you if requested. Check out the easy how to use guide for PestFacts map to see how to report and view historical records.
The latest information for growers and advisors on the activity and management of pests in all broadacre crops during the winter growing season.
