Can you confidently identify armyworm and helicoverpa larvae in winter cereals?

Both Heli­cov­er­pa armigera and army­worm lar­vae are occur­ring togeth­er in wheat and bar­ley. It is impor­tant to be able to sep­a­rate the heli­cov­er­pa lar­vae from the army­worm lar­vae in order to deter­mine whether the num­bers are above or below thresh­old, and, if need­ed, to make the most appro­pri­ate deci­sion about con­trol options.

Army­worm lar­vae

  • have three white stripes on the col­lar, behind the head. These stripes may or may not per­sist down the body so con­cen­trate on the col­lar (see the image above at right).
  • skin is smooth with­out obvi­ous hairs and bumps.
  • larg­er lar­vae tend to curl up when dis­turbed.

Heli­cov­er­pa lar­vae

  • skin is lumpy with obvi­ous hairs.
  • may be con­sid­er­able vari­a­tion in colour.
  • may or may not have a ‘sad­dle’.