Foam-adhesive
Guides
Aphrophora alni
European alder spittle bug, alder spittlebug
Aphrophora alni is a froghopper in the family Aphrophoridae, commonly known as the European alder spittlebug. It is the most common and widespread of the four Aphrophora species in the UK and one of the larger froghoppers in its range. Adults are distinguished by a pale median keel on the head and pronotum, dark brown coloration, and two pale patches along the costal margin of the forewings. The species is polyphagous, feeding on deciduous trees as adults and herbaceous plants as larvae. Nymphs produce characteristic foam nests ('cuckoo spit') with adhesive properties of biotechnological interest. It has been recorded as a pest on alder and is a potential vector of the bacterial plant pathogen Xylella fastidiosa.