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 overwhelmed 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 panhandle Florida homeowners and gardeners when encountering armyworms. This native insect has the scourging ability of an Old Testament plague.
Southern Armyworms are in seasonal retreat. Still there are caterpillars eating ornamental shrubs and garden plants in the panhandle.
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 domestically extends through Central America to most of South America. Domestically, it is concentrated in the southeastern states, but it 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 it 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 ornamentals 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 on desirable plants.
This species’ life cycle takes about 40 days to two months to complete. Depending on weather conditions, about four cycles are completed annually in north Florida, with the highest populations being found during late summer and the warm days of 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 a cocoon or chrysalis hanging from stems of their host plant.
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, so the pillage and plunder continues unless defenses are initiated.
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