“The quality of mercy is not strained, it droppeth as the gentle rain from heaven,” so wrote the Bard of Avon, William Shakespeare in his classic play the Merchant of Venice.
Rains in Florida’s 2020 warm season have been gentle, and not so gentle at times, but at least there has been enough of them. The occasional muddy roads and full ditches are mute testament to this bounty from above along with the lush growth of plants and trees.
The ample development of foliage county-wide had proven to be an unending buffet for all those insects and arthropods dependent upon a leafy diet. Their days are spent eating, moving to new dining options and producing replacements that can begin the cycle again.
Included among the ala-carte insect menu items are the plentiful oaks in north Florida. Unfortunately, for anyone who tarries too long beneath one of these oak trees which is, at the time, functioning as a caterpillar café will experience something else dropping from above.
The small dark brown chunks falling from oak trees are not pollen or wither acorns. Populations of oakworms release their waste on anything below the oak leaves.
Local oakworms are hard at work preparing to preserve their species for the waning days of autumn. Their numbers are building up in the favorable weather conditions of a wet summer which produces the nourishment to consume and support their reproductive efforts.
One of the active species frequently encountered is the Spiny Oakworms (Anisota stigma). This is one member of a moth genus which is actually a caterpillar instead of a true worm.
The common spiny oakworm population is currently at work eating their way through the several native oak tree species. Luckily, the oaks grow faster than these caterpillars can eat.
The difference between worms and caterpillars is substantial, but caterpillars are often misidentified as worms. Their tubular shape is a stage of life for a caterpillar which ultimately becomes a butterfly or moth.
The tubular shape is usually the development pinnacle of the worm’s life cycle. Most caterpillars tend to eat live vegetation, while worms usually consume dead plants or animals which accelerates the deceased’s decomposition and returns their nutrients to the soil.
Healthy small oaks usually have enough vigor to leaf-out and survive the assault carried out by the Oakworms. Larger oaks have enough leaf producing capacity to out produce the caterpillars’ collective ability to eat.
In addition to the Spiny Oakworms, there are Red-humped Oakworms, Yellow Striped Oakworms and others which are native to north Florida. As their name implies, oak leaves are the nourishment of choice.
All the oakworms are about an inch in length with bristly hairs, especially in the case of the Spiny Oakworm. Colors and body patterns are the simplest way to identify the species in this genus.
These caterpillars are rarely seen alone in a tree. They are commonly found in colonies of 50 or more, each dining on a leaf, and their droppings literally rain down on anything or anyone below them.
Pink oakworms are one of the variants currently dining on autumn’s plentiful supply of north Florida oaks. Anyone or anything below these native caterpillars may experience the effects gravity has on their waste.
When threatened, they curl into a U shape and remain still. Predators are commonly confused by the behavior and seek other meal choices.
Home owners and landscape managers sometimes seek methods for controlling these caterpillars, but nature does the best job. Caterpillar populations will peak in late summer to early autumn with birds, bats and others feasting on the defenseless moths before they can lay eggs.
The best advice is not to look up when under an oak tree as there may be an unpleasant surprise raining down.
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