Facts about armyworm

from The Zimbabwean
Published on 08 Feb 2013 View Original

Armyworm outbreaks were reported in the first week of January, threatening to worsen the country’s already precarious food security.

The outbreak was first detected in Mashonaland Central and later on spread to other areas such as Mashonaland West, Manicaland, Midlands and Matabeleland North where hundreds of hectares of maize crop were reportedly destroyed.

Agritex Plant Protection Research Institute head, Godfrey Chikwenhure said the armyworms were originating from Zambia, Uganda and Tanzania and are blown into the country when strong moist winds bring rain. Armyworm outbreaks normally increase when rains fall.

The armyworm is a stout bodied, hairless, striped caterpillar that ravages the foliage of grasses and grain crops. When mature they are usually about an inch and a half long. The name is derived from their habit of marching from field to field in search of food in a soldierly fashion.

The pests breed when armyworm moths lay eggs at night usually in the folded parts of the leaves of grain plants and grasses that are moist. The eggs will hatch in eight to 10 days and the larvae will consume all the food around them until they are fully grown.

In the event of a food shortage the armyworm move in large numbers from one field to another in search of vegetation, feeding and travelling during the night in their search for new sources of food.

During the day, they hide under the leaves or in loose soil. When the pest finishes feeding, it will burrow in the soil and pupate. In two weeks, they hatch and mate, beginning the cycle again.

Since they feed at night, the armyworms are usually difficult to detect until extensive damage is done to the crops. Early detection of the pest is therefore critical.

To detect armyworm outbreaks, farmers should monitor their fields in spring for signs of armyworm. Some of the signs of presence of armyworm include holes in the leaves of crops or pieces missing from the edges of the leaf.

Farmers should look under the plants for armyworms or signs of their droppings. At times larvae is found under plant debris lying in the field. An increase in the number of birds, known predators to the pests, in the field can be a sign of an outbreak of this pest.