Ravenous armyworms launch waves of attacks

It is a situation which has been repeated countless time
over the course of recorded history in countries and continents across the
globe. In all likelihood the scenario occurred, albeit on a much smaller scale,
in the days which predated the written accountings of the destruction.

An assemblage gathered with the sole objective to pillage
and plunder the resources produced by others. Usually, the invaders were
undetected until they fell upon their objective and overwhelm the meager
defenses.

Too often the defenders offer little resistance and are
unable to initiate a plausible counterattack. Once the horde has departed,
those who were robbed must start again from the beginning.

On a much smaller scale, this can be the experience of Franklin
and Gulf counties’ homeowners and gardeners when encountering armyworms. This
native insect has the scourging ability of an Old Testament plague.

Much like ancient military organizations, the armyworms’
campaign of destruction begins in spring. The first wave of attack is conducted
by the Southern Armyworm (Spodoptera eridania).

The distribution of this pest in the Western Hemisphere
extends through Central America to most of South America. Domestically, it is
concentrated in the Southeastern states, but is also present in New Mexico,
Kansas and California.

The larval state of this moth is not a picky eater. In
untended areas it will eat a variety of weeds, but has a preference for
pokeweed and pigweed. Native grasses are not usually on the menu for this pest.

Unfortunately for humanity, armyworms will eat most of the
crops and ornamental which are useful for food production and landscaping
purposes. Flowering shrubs, garden plants, fruit trees and field crops are all
under the threat of foliar pillaging by these ravenous caterpillars.

In north Florida these insects are most active during the
warmer seasons of the year. The moths are active all year and are capable of
surviving several days of freezing weather.

Earth toned and about 1.5 inches wide, the rarely seen
adults of this species are most active at night. Unlike their colorful cousins
which attract the attention of people concerned about the native pollinators,
these night-fliers perform the same function but leave eggs which produce
problems.

This species life cycle takes about 40 days to two months to
complete. Depending on weather conditions about four cycles are completed
annually with the highest populations being found in late summer and early
autumn.

When the caterpillars have had their fill of eating, they
retreat to the upper few inches of soil near their host plants to pupate and
develop into a moth. Unlike butterflies, they do not have cocoons hanging from
stems.

The repose between the two forms (caterpillar and moth) of
this species takes about two weeks. When conversion is complete the adult moth
emerges, and the cycle begins again.

A number of species prey upon this caterpillar. In addition to
the night foraging animals which visit landscapes and gardens seeking a quick
snack, there are parasitoid wasps which use the Southern armyworm as part of
its reproductive process.

Any adult moths so foolish as to venture into the open night
may become the target of bats. The aerial attack on the infantry has only a
minor effect of the population of the armyworms.

As autumn progresses the Southern Armyworm’s activity slows.
The second wave of the attack is then undertaken by the Fall Armyworm.

To learn more about this hungry pest
in Franklin and Gulf counties, contact the nearest UF/IFAS County Extension
Office. To read more
stories by Les Harrison visit: Outdoorauthor.com and follow me on Facebook.