Reduces production and quality of older plants during the growing season
Reduces seed yield of legumes in spring
Silvering of leaves, distortion of leaf shape in broadleaf crops.
Affected seedlings can die.
Seedlings can be killed below ground before they emerge.
In pastures, majority of damage occurs to clover and medics.
Active during cool, wet months (May to November). Hatch in autumn from over-summering eggs. Hatching triggered by a significant rainfall event in combination with 7-10 days of mean temperatures below 21ºC.
Over-summering eggs – produced in late spring. RLEM survive in diapause until autumn conditions trigger hatching.
Blue oat mite (BOM)Image: cesar
Adults similar in size to RLEM
Black body with red legs and small oval red area on back distinguishes it from RLEM.
Silvering of leaves (cereals, pasture, canola)
High infestations in winter cereals can cause leaf tips to wither and seedling death
Reduces growth of older plants and can impact on yield of legumes in spring.
In winter pastures, most damage and loss is to grass component
Penthaleus spp. have specific host preferences:
P. major – pasture, oats, wheat
P. falcatus – canola, broadleaf weeds
P. tectus – oats, wheat, barley
Winter/spring. Hatch in autumn from over-summering eggs
At the end of spring the mites produce thick-walled over-summering eggs that are resistant to dry conditions.
Mites are most easily seen in the late afternoon when they begin feeding on leaves.
Balaustium miteImage: cesar
Up to 3 mm in length, adult almost twice the size of RLEM.
Nymphs bright red.
Body brown/greyish-red with red legs
Short stout hairs covering body (microscope)
Feed on plants and predatory on other mites
Canola: distorted and cupped cotyledons
Pulses & cereals: bleaching of leaves especially leaftips
More likely to cause damage in warm, dry seasons. Lower risk of damage in cool, wet seasons. Can overwinter as eggs, but will survive all year round providing there is green plant material and protection from extreme temperatures. Hatching of overwintering eggs occurs when conditions warm and dry spring conditions prevail.
More easily found in warmest part of the day. Often found in southern coastal areas. Less abundant than other mites
Bryobia mite or clover miteImage: cesar
Adult mites 0.75 mm in length, oval, rusty brown/orange – olive in colour
Legs pale red/orange with long front legs held out in front of the body (may be mistaken for antennae)
Nymphs bright red with pale legs
Bryobia less active on the plant than RLEM.
Damages canola, wheat, lupins, clover
Feed upper surfaces of leaves, leaving long trails of whitish grey spots.
On succulent growth, early damage may look like leaf miner damage.
In grasses and winter cereals, feeding damage results in silvering, but economic damage is uncommon
In broadleaf crops, Bryobia causes similar damage to RLEM
Survive all year round providing there is green plant material. May not survive cold or very dry conditions unless protected. Overwintering eggs laid in early–mid winter and hatch as conditions warm up
Most active in warm conditions in spring, summer and autumn. Summer rains followed by warm mild autumns give bryobia mites the best conditions for survival and increase.
Further information
RLEM status and control by Louise Lawrence, CSIRO Entomology – in Australian Grain – 19 – Nov-Dec 2009