Froghoppers feed by sucking sap, usually from plant stems but the nymphs of the red and black froghopper feed on plant roots. Almost uniquely they suck liquid from the xylem vessels of the plant, which contains mainly water from the roots, and has low nutrient value. Most plan suckers raid the phloem vessels which carry sugars and amino acids from the leaves.Froghopper nymphs are soft-bodied, creamy white smaller versions of the adult insects that gradually develop the adult features as they mature. The nymphs secrete an acrid frothy liquid from their rear end and are concealed within individual bubble baths commonly known as cuckoo spit. This is probably a consequence of having to get rid of an excess of water from its xylem feeding. Once the insect has reached the adult stage it no longer produces cuckoo spit and they move freely on plants, unlike the sedentary nymphs. When disturbed, adult froghoppers will leap away from danger.
Most species of froghopper deposit their eggs in late summer-autumn in bark crevices on the stems of plants. The eggs overwinter and the nymphs hatch in late spring. The blobs of white froth produced by the nymphs are frequently seen in late April-June. The insects become adult from July onwards. There is one generation a year. The red and black froghopper overwinters underground as young nymphs that complete their development in the following spring.
Role of froghoppers in gardens
The presence of cuckoo spit on garden plants in late spring-early summer may be considered unsightly but froghoppers have little impact on the growth or health of plants. The froth disappears from plants once the nymphs reach the adult stage in mid-summer.
Cuckoo spit is thought to be a means by which the nymphs protect themselves from predators. However, a solitary wasp, Argogorytes mystaceus, specialises in extracting froghopper nymphs from the froth and uses them as a food store for the wasp’s larvae.
There is current concern that the bacterial plant disease Xylella
could enter Britain with possibly devastating efffects. Froghoppers are potential vectors, and people are being encouraged to report sightings
Other sources of information
Le Quesne, W. J. (1965) Handbooks for the Identification of British Insects Vol 2 part 2a. Hemiptera Cicamorpha Royal Entomological Society – out of print but available as a free download from here
1. Malcolm Burrows, M. 2006. Jumping performance of froghopper insects. Journal of Experimental Biology 209
: 4607-4621 link here
Page drafted by Andrew Halstead, reviewed by Andrew Salisbury, edited by Steve Head