Newly hatched spittlebugs active
Otago Museum
SMALL globes of froth are now very conspicuous on a great variety of native and introduced plants. These are caused by meadow spittlebugs Philaneus spumarius, a European species that first appeared in numbers in Dunedin in 1984. A native species Carysytoterpa fingens, is similar, but occurs on far fewer plant species.
Spittlebug froth usually appears in early summer and has disappeared by late December.
The female spittlebug lays its eggs in autumn. There are five juvenile stages, called nymphs. Newly hatched spittlebugs are extremely active and wander about until they find a suitable hostplant.
Once this is done, the young nymph inserts its beak and proceeds to draw sap. A filtering chamber in the oesophagus passes most of the excess water and much of the sugar to the posterior part of the gut. This bypass results in considerably more sap being sucked up than is digested and the excess flows out the anus and adheres to the plant and the nymph.
Soon, a droplet covers the entire nymph. It breathes by means of a tubelike canal below the abdomen. Nymphs produce bubbles by vigorous motions of the abdomen — the air canal is filled with air as the abdomen is thrust outside the fluid mass and the abdomen is then strongly contracted within the fluid, forcing a bubble out of the tip.
In a few days, all remaining spittlebugs will have changed into the adult froghopper stage, which does not secrete spittle.
Although the general shape is constant, the colour is very variable, ranging from pale buff to almost black.
A study in England related dark coloration in individuals occurring downwind from a factory to the local effects of smoke emitted from the factory chimneys — a case of smallscale industrial melanism. Most froghoppers around Dunedin are tancoloured.