Consists of at least 2 species which may be difficult to tell apart
Widespread native insects, occasionally reaching pest levels
Feed on a range of plants including plantain
Their recent appearance in large numbers in plantain crops has given rise to the name Plantain moth. It belongs to a group of moths commonly called carpet moths
Moths are small, less than 20 mm wide, light brown with darker spots and a distinct darker brown band towards the end on the wings. Darker band more pronounced on E. rosearia while S. rubriaria has a more spotted pattern.
Moths will fly up from the crop in front of people stock or vehicles, sometimes in very large numbers
Caterpillars of S. rubraria are brown but vary greatly in tone and pattern. E. rosearia caterpillars may be green or brown. Both are less than 20 mm long
Caterpillars are loopers, they raise part of their body off the ground or plant when moving.
Biology
Very little is known about the biology of these insects
They are native moths/caterpillars, of a type commonly called loopers, found throughout New Zealand and also Australia
They are widespread in New Zealand occasionally reaching very high levels in plantain crops
They have short generation times and several generations per year occur
It is likely that development is temperature driven and that it is favoured by warm weather
They are most abundant in late summer and largely disappears from crops in autumn
They probably feed on a wide range of plants but are usually associated with plantain species and appear to find “Tonic” plantain to their liking having been observed causing noticeable, sometimes very severe, damage to crops.
Impacts
The caterpillars feed on the plant leaves causing small holes which can join up and in severe cases leave only leaf veins
Generally little plant damage is attributed to this insect but it is very commonly found in plantain stands and damage to “Tonic” plantain is frequently reported
Normally the growth of plantain is so great that feeding by these caterpillars has very little impact on plant production
Occasionally however, severe damage is reported as a consequence of very high caterpillar numbers and may be concentrated in some paddocks while others close by are unaffected
Why, and how, this situation arises is currently unknown but is under investigation
Crop health, plant stress and growing conditions may have a significant role to play in the severity of damage observed.
Control
There are no registered insecticides for control of plantain moth caterpillars but broad spectrum insecticides with good activity against other caterpillars may also provide control of plantain moth. It would be wise to consult with agrichemical professionals before using these insecticides for off label use
Too little is currently known about this insect for management options that may affect build-up of caterpillars to be suggested. When its biology is better known some options may present themselves
As a general guide a healthy crop will tolerate more insect damage than an unhealthy one.
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