Getting to the bottom of the ‘The Spittlebug Story’
When my son, now grown, was about 9 or 10, he queried me one summer day about the foamy bubbles in the tall grass of a meadow above the house.
“Why’s that snot in the weeds?” he asked.
“Frog spit,” I said, exhausting my knowledge of the subject. That’s what I’d been told as a boy, and that’s all I knew about the small masses of froth that mysteriously appear in the weeds each year.
We examined several of the globules with our fingertips and discovered one or two critters sequestered within each. They were greenish-brown and did resemble tiny frogs, but they were obviously some form of insect.
A little field guide research back at the house uncovered the basic information that they’re the nymphal form of several insect species variously known as spittlebugs or froghoppers.
By that time my son already knew more than he cared to know about the matter and moved on to other interests. But I’ve expanded my spittlebug research program through the years, collecting scraps of information on these curious insects. Here then is “The Spittlebug Story” as I now understand it.
In late fall adult froghoppers deposit frost-resistant eggs in the angle between the leaf and stem of a plant. The nymphs that hatch out in spring feed upon the plant’s juices, positioning themselves upside down so that excess juices are excreted from the insect’s anus, thus allowing gravity to cause the slick fluid — which contains a waxy substance produced in the abdomen — to coat their bodies.
According to entymologist Ross Hutchins, “The basic substance composing this foam comes from the Malpighian tubes or excretory tube organs and more or less resembles silk in its chemical nature.”
Two abdominal segments are equipped with pump-like glands (“spiracles” or “breathing pores”) that in a short while produce a frothy mass the consistency of saliva. That’s how it’s done — but why? Here are some of the theories.
• The process gives the insect (which spends most of its nymphal life sucking juice from plant stems) a way to get rid of excess fluids. The canopy of resulting spittle also provides the nymph with a moist and cool environment in which to mature. They quickly dry up and die when removed from their spittle dwellings.
• Most observers assume that these masses also serve as camouflage from birds. But it turns out that the spittlebug’s main predator is a wasp which has learned that if it lays its eggs in the conspicuous froth the baby wasps will have tasty spittlebugs to feed upon.
• At least one spittlebug authority asserts that the primary objective of the spittle mass is not camouflage — “for the spittle is white and obvious” — but rather to “provide a distasteful substance that a predator would have to search through.”
Now, I don’t mind poking my finger into the spittlebug’s domain in order to examine the little bugs therein, which are sort of cute in an insect kind of way. I do that at least several times a year. But I draw the line at tasting of the stuff. Someone else is going to have to determine whether or not it’s “distasteful.”
So, there you go. When your son or daughter asks “Why’s that snot in the weeds?” you can simply say “Frog spit” and keep on trucking; or, you can hunker down and reel off “The Spittlebug Story.”