Red clover moth pests found all over NZ

Adult red clover casebearer moths are about 8mm long and are most likely to be seen between October and January.

A red clover pest first formally identified in New Zealand just 15 months ago, has now been found right across New Zealand.

FAR seed research manager Richard Chynoweth says the red clover case bearer moth (Coleophora deauratella) was discovered in Auckland in October 2016, setting off alarm bells and prompting a nationwide monitoring campaign.

"Traps were placed on farms from the lower North Island to the south of the South Island. The results are not good news for red clover growers, with moths being found on farms, roadsides and other areas everywhere from Wairarapa to Southland.

As it was first identified in Auckland, we can assume they will be found across the North Island as well. Given the numbers and spread of this pest, it seems likely that it has been here for quite a while. My guess would be that it's been around for at least a decade and could have been affecting red clover seed yields for several years."

Red clover casebearer is a small moth (about 8mm long) and is very similar to two other species of clover casebearer moth (Coleophora spp.) that are already well established in white clover in New Zealand, however in this case, its principal host is red clover.

Adult moths lay eggs on developing red clover flower heads and once hatched, the larvae tunnel into the florets to feed, destroying the growing seed. As the larvae grow, they adhere themselves to a chewed off floret, using it like a cape or case for protection and camouflage. Feeding damage to seeds can severely impact on crop yields.

Richard Chynoweth explains that as not a lot is known about red clover casebearer in New Zealand, researchers have a lot of work on their hands.

"We will continue to monitor its spread, but more importantly, we need to understand its life cycle and exactly how that links with the red clover growth cycle. Once we have a clearer idea of that, we can start to consider control options, so that arable farmers can continue to grow this specialist crop.

Farmers who wish to check their crops for the presence of red clover casebearer, should inspect flowers looking for millimetre sized holes chewed into the base of individual florets and, or, distinctive black droppings, also at the base of the florets.

They may also be able to see the case bearing larvae, which look like small red-brown cigars on the flowers. If evidence of casebearer is found, discuss management with your crop agrichemical adviser.