Philaenus

Philaenus is a genus of insects in the family Aphrophoridae, commonly known as froghoppers or spittlebugs. Members of this genus are small sap-sucking insects found in temperate and subtropical regions worldwide. The best-known species is Philaenus spumarius, the meadow spittlebug, a widespread representative in both natural and agricultural habitats.

Adults of Philaenus species are compact, typically 4 to 6 millimeters long, with a slender body and variable brown to gray coloration. They hold their wings tent-like over the body when at rest. Nymphs are most familiar for their behavior of living inside protective foams called spittle, which they produce by exuding a frothy mixture around themselves on herbaceous plants. The foam helps conserve moisture and hides the nymphs from some predators.

The life cycle begins with eggs laid on plant stems in late summer or autumn. Eggs overwinter and hatch in spring. Nymphs pass through several instars while developing within spittle masses before moult into winged or wingless adults. In favorable climates, some Philaenus species produce two or more generations per year, with adults continuing to fly in search of new hosts.

Ecologically, Philaenus species are predominantly xylem-sap feeders and have a wide host range that includes grasses, herbs, and shrubs. While their feeding generally causes limited direct damage, heavy infestations can weaken plants. Importantly, Philaenus spumarius and related species are vectors for plant pathogens, notably the bacterial Xylella fastidiosa, contributing to the spread of diseases in several regions.

Distribution covers the Holarctic region, with species present across Europe, Asia, and North America. The genus is of interest in agricultural and plant-disease contexts due to its ecology, life history, and vector potential.