Montana Public Radio

Bug Bytes: Spittlebugs

Jun 12, 2020

You’re in your garden or maybe out for a walk in the woods … and you come across what looks like a fresh loogie someone just spit onto a plant. Gross!

Relax. A fellow human likely did not leave behind the white, foamy goop. It’s the telltale sign of a spittlebug.

Spittlebugs are the immature stage of insects commonly referred to as froghoppers. They are part of a family of sap sucking true bugs…and like their relatives, have a beaklike mouthpart that’s used to tap into the watery sap of plants.

The sap has very little nutritional content, so spittlebugs need to drink A LOT – about 200 times their body weight every day. That’s the equivalent of a 150-pound human drinking over 3,500 gallons of water in a day. And as we all know, that means a lot of trips to the bathroom.

A spittlebug nymph and adults.
Credit Missoula Insectarium

So, if you pretty much need to go all the time, you might as well make good use of your pee. By whipping air bubbles into their mucusy waste, spittlebugs form a spit-like blob. But instead of leaving their waste behind, spittlebugs use this as a perfect hideaway.

Surrounded by their frothy pee, spittlebugs are hidden from predators. It also provides thermal and moisture control (so the nymph does not dry up). And the spittle has an acrid taste, further deterring predators from a spittlebug meal.

And as far as human disturbance…who really wants to go poking into something that looks like fresh spit?

Once the spittlebug becomes an adult, it leaves the protective goo behind and continues its diet of plant sap out in the open.

So, the next time you come across one of those gross-looking blobs, take a closer look for the little bug inside that’s responsible for all that goop.