Armyworm is identified with white bead-like small eggs.
Larvae are smooth-bodied and can be dark-green, brown or black, with alternating light and dark stripes running along the body.
Larvae feed at night and this is why it is difficult to detect them.
During daytime, they hide under crop debris. But eventually, they grow and turn into moths, they have dull fore wings, grey/brown in colour, with a distinctive white dot in the centre.
The hind legs are pale white with a slightly darker area on the edge.
Because they hide during the day and feed at night, it is difficult to detect them until one’s maize is destroyed.
Mature moths prefer dense plants and heavy infestation is common in weedy and congested farms. This means that keeping your farm free of weeds can reduce the possibility of these worm attacks.
But overall, the larvae are responsible for 80% of the destruction and if they are not handled early enough, they can easily eat up entire farms.
The signs that a farm has been attacked by the worms include perforated leaves caused by young larvae, ragged leaf appearance and lost foliar tissue.
You can also see large numbers of caterpillars migrating across the fields. Therefore, monitoring for the presence of armyworms in your field is critical, in order to avoid complete destruction of your crop.
Fields must be regularly inspected for the presence of eggs, worm’ faeces and young larvae on the underside of leaves.
Chemical control
Armyworms must be sprayed when they are still at the early larvae stage if chemical control is to be effective. Insecticides must be applied during the larvae stage if infestation levels are high.
It should be applied at night or during dark periods of the day when they are out feeding.
There are various insecticides with active ingredients such as bifenthrin, lambda and organophosphates that are approved for armyworm control.
However, one needs to consult the nearest extension worker, most likely at one’s sub-county before selecting the insecticide.
