Black cutworm: potato and cabbage pest in Indonesia and Western Australia

Page last updated: Wednesday, 9 May 2018 - 11:21am

Please note: This content may be out of date and is currently under review.

Black cutworm is a relatively minor pest of potatoes and cabbages in Indonesia and Western Australia.

The Department of Primary Industries and Regional Development, Western Australia has worked with the Indonesian potato industry to increase the productivity of Indonesian crops planted with WA seed potatoes.

Improved productivity requires accurate identification of pests in potatoes as well as in the cabbage rotation crop.

As well as helping Indonesian farmers this information will assist Western Australian seed potato exporters understand the challenges their Indonesian customers face.

Identification

Black cutworm’s Indonesian name is "ulat tanah" and its scientific name is Agrotis ipsilon.

Black cutworm moth

Black cutworm moths are about 25mm long with a wingspan of about 50mm. They have dark upper wings and white to grey lower wings. They are strong flyers and moths are active from sunset and at night.

They are attracted to weedy or vegetated areas and lay hundreds of eggs near the soil surface on living plants or organic matter.

After the eggs hatch, the young larvae feed on plants or decaying organic matter.

Black cutworm larva
When disturbed, black cutworm larvae form a tight curl
Black cutworm larvae curl up when disturbed

Mature black cutworm larvae grow to about 40mm long. They are grey to black with a brown head.

Larvae are most active at night. During the day, they burrow into soil and can be found near the bases of damaged plants.

Black cutworm larvae curl up when disturbed.

Black cutworm larvae sever seedlings at ground level. Photo courtesy IPM Images USA
Black cutworm and severed seedling. Image courtesy IPM Images USA

An infestation of black cutworm larvae is noticed when they chew stems of transplanted cabbage seedlings or emerging stems of potato plants which wilt and die.

Black cutworm larva and damage to a potato tuber
Potato tuber damage from black cutworm larva

If present in potato crops near harvest, black cutworm larvae will chew holes in potato tubers making them unmarketable.

The cocoon stage of black cutworm. Photo courtesy IPM Images, USA
The cocoon stage of black cutworm. Photo courtesy IPM Images, USA

When mature, black cutworm larvae burrow into the soil to about 50mm and form a cocoon. These cocoons are about 25mm long and light brown. They darken as the pupa develops and the moth emerges from it.

Contact information

Stewart Learmonth
+61 (0)8 9777 0167

Black cutworm: potato and cabbage pest in Indonesia and Western Australia

Author

Stewart Learmonth