Editor | On 27, Oct 2019

Darrell Mann

The froghoppers, or the superfamily Cercopoidea, are a group of hemipteran insects in the suborder Auchenorrhyncha. Adults are capable of jumping many times their height and length, giving the group their common name. They are perhaps best known, however, for their plant-sucking nymphs, ‘spittlebugs’ which encase themselves in foam in springtime.

The foam is a lovely solution to a safety problem. Spittlebugs are prey for a number of larger insects. By making a cloud of (unpleasant tasting) bubbles around themselves, they manage to avoid nearly all these predators. The foam is a great way of making a little go a long way. The spittlebugs suck on the sap from their host plant. The sap is quite low on nutrients, so the nymphs have to process a lot of it. Up to 150 times their body weight in a day sometimes. Rather than just excreting the spent sap, the nymphs transform it into the foam and thus get a two-for-one benefit: nutrients and protection.

From a contradiction perspective, the protection part of the problem looks something like this:

Inventive Principles 31 (Porous Materials) and 30 (Flexible Shells & Thin Films) both point us directly to the foam solution. Principles 9, Prior-Counteraction and 5, Merging also make for a pretty good proxy for the two-for-one benefit. Principle 40 points towards the addition of the foul-tasting additive that makes the foam unappealing to predators.

Biologists have recently realized that the spittlebug tends to come out of the foam to breathe. Then, when a predator appears, the nymph disappears into the foam again. Where, if the predator hangs around for a long time, the cunning spittlebug is still able to breathe by piercing some of the foam bubbles and breathing the air they contain. Does that make it a three-for-one solution? Protection, way of processing waste and emergency air-supply. Who’d’a thunk of that?

Lovely video: https://www.nytimes.com/