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Surface Feeders - Fall Armyworm (FAW)
FIELD KEYS
Hosts: bermudagrass, bluegrass, bentgrass, ryegrass, fescues
Site symptoms: Small to larger areas of sunken or thinned turf
that gets larger with time Turf often has flocks of feeding birds.
Plant symptoms: The undersides of leaves are skeletonized by small
1st instar feeding with full grown larval feeding on all above-ground
plant parts. Frequently larva leave partly eaten plant parts scattered
on soil or thatch surface.
Site keys: Low, wet or transitionally shaded areas.
SPECIMEN ID
Fully grown FAW larvae can reach 2 inches long with four small black spots
on the top of each segment and dark stripes down each side. Adults are
gray brown moths with 1-inch-long, narrow, football-shaped bodies and
1 ½ inch wing spans. The forewings are dull gray mottled with darker spots
and the hind-wings are yellow to white at the edges and almost translucent
in the centers.
SCOUTING TIPS
Although FAWs can occasionally be found as far north as the Canadian border,
they are primarily a pest of the middle and lower portions of the country,
where they can be abundant. FAWs are very cold sensitive so they annually
migrate to northern regions by flying into weather fronts sweeping up
from warmer regions. The moths frequently lay egg masses on trees and
other vertical surfaces, with the newly-hatched larvae lowering themselves
down to the turf on silken strands. FAWs have short life cycles of as
little as 3-4 weeks, so warmer regions can have multiple generations per
year.
CONTROL STRATEGIES
Cultural: FAWs have lots of natural predators, ranging from parasites
to birds. Larval populations can be monitored using soap or insecticide
flushes or by collecting and quantifying when larva feed at night. Minor
infestations late in the year often do not require treatment.
Chemical: If FAWs are a consistent pest try to correlate data on
population numbers with the time of year and observed damage when making
control decisions. Tall cut turf can tolerate a higher population than
can shorter cut sites. FAWs rarely damage large areas of turf. Their larvae
are often localized; the damaged turf can recover quickly if spot treatments
of insecticides are used.
Growth stages: egg-grub (several instars)* - pupa - adult
* - treatable stages
Life Cycle: 1 year life cycle (multiple generations in warmer regions)
Sequence: adult - egg - larva - pupa - adult
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