Tuesday, June 21, 2011

Adirondack Insects: The Spittlebug

After several days without a significant rain, an observant gardener pulling up clumps of weeds, or a perceptive hiker traveling through a pine forest or a meadow near a stand of conifers may notice a glob of saliva-like fluid attached to a wildflower stalk or the stem of a piece of grass.

Occasionally referred to by some people as snake spit, or frog spit, this common frothy deposit of whitish, watery liquid is neither associated with a snake or frog, nor is it produced by the salivary glands of any creature. The spit-like fluid seen on various plants during the early days of summer in the Adirondacks is a form of protective enclosure that surrounds a small insect known as the spittlebug.

The spittlebug is a common, yet rarely seen creature that is closely related to the aphids and cicadas. The spittlebug’s habit of hiding in a layer of nearly opaque fluid makes it impossible to see, unless the white, watery foam is absorbed by a tissue or a piece of paper towel. Even then, the green color of this bug and its small size, which is around a quarter of an inch, makes it a challenge to spot.

On those occasions following a moderate to heavy rain, when its protective veil gets washed away, chances are that the spittlebug will only be seen by a few creatures that reside in the general surroundings. It doesn’t take long after its protective covering is removed for this bug to generate another coating of tiny white bubbles which again conceal it from those predatory creatures that would prey on it.

In the Adirondacks, spittlebugs pass the winter in the egg stage of their life cycle. As summer wanes, these eggs are often placed beneath pieces of dead bark, or under other surface irregularities on small twigs, and in tiny crevices toward the end of outer branches on certain evergreen trees, especially the pines.

After the threat of the last frost has passed in late spring, the eggs hatch into nymphs. (Since these bugs experience an incomplete metamorphosis, the intermediate stage in their development is called a nymph.) Some nymphs may fall off the trees and land on various forms of vegetation below. If this occurs, the nymph begins to search for a succulent plant on which to attach itself so it can feast on the nutrient enriched fluids present within the plant’s vascular tissue. After absorbing the substances that serve as food, the spittlebug then takes the remaining fluid and adds tiny air bubbles to create the saliva-like deposit that engulfs this immature bug.

Not only does this mass of fluid help to conceal the nymph, but it also protects it against adverse weather conditions that can develop at this time of year. Brief spells of intense heat, periods of low humidity that can cause desiccation in such a delicate bug, and cool temperatures at night are conditions that the spittlebug is protected against when shrouded by its layer of foam.

Between molts, the nymph may travel to a new section of the same plant, or an entirely different form of vegetation. After it experiences its final molt, and emerges into its adult stage, the spittlebug no longer hides in a saliva-like covering.

While the adult has two sets of wings, this bug only occasionally uses these appendages to travel. After breeding, a spittlebug may settle on a suitable pine tree and remain in the general vicinity for the rest of its life. The adult continues to extract fluid from the tree for use as food, but not as shelter. The females lay their eggs in nooks and crannies, where they will be difficult for other creatures to find. Birds like the chickadee and nuthatch regularly scour such tiny cracks and crevices on trees throughout the long winter season in their attempts to find invertebrate matter, like the eggs of the spittlebug to eat.

It is believed that the spittlebug, like aphids, inflict little harm on the plants which they parasitize. Because these insects are so small and remove such limited quantities of nutrients, they have about the same impact as do mosquitoes on humans. Spittlebugs are only considered to be a serious pest when they occur in large numbers, or should they happen to be carrying a strain of bacteria or fungi that is harmful to the host plant. However, the population of these bugs rarely swells to epidemic levels, as there always seem to be enough predators that can find and eat these unique insects here in the Adirondacks.

Photo: Spittlebug in larval form, courtesy Wikipedia.

Tom Kalinowski has written several books on nature in the Adirondacks.

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Tom Kalinowski is an avid outdoor enthusiast who taught field biology and ecology at Saranac Lake High School for 33 years. He has written numerous articles on natural history for Adirondack Life, The Conservationist, and Adirondack Explorer magazines and a weekly nature column for the Lake Placid News. In addition, Tom’s books, An Adirondack Almanac, and his most recent work entitled Adirondack Nature Notes, focuses on various events that occur among the region’s flora and fauna during very specific times of the calendar year. He also spends time photographing wildlife. Tom’s pictures have appeared in various publications across the New York State.

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