Bugging You From San Juan Island

I took this photo of a Meadow Spittlebug (Philaenus spumarius) on September 7, 2019 when I attended the San Juan County Land Bank’s open house at the new Zylstra Lake Preserve http://sjclandbank.org/zylstra-lake-preserve-san-juan-island/ . It was a bit cloudy, but fortunately it didn’t rain during the event.

While there weren’t many insects out and about, I was happy to get a shot of the adult version of this species. It was hanging out with some family members on the stem of a thistle growing alongside the walking path.

Spittlebugs are in the insect order Hemiptera and the family Cercopidae (1). You might recognize these as the mystery bug that hides as a nymph inside a frothy dollop of bubbles on stems of vegetation. This particular species is widespread in North America and very common in the Pacific Northwest (1). So, if you’re out for a walk in the springtime, you’ll see lots of vegetation that appears to have wads of spit stuck to it…and the tiny meadow nymph is hiding inside!

The Meadow Spittlebug (Philaenus spumarius) is also known as the Common Froghopper and it does indeed look very frog like to me. 🐸 Even more interesting, a Google search of the etymology of this little bug’s name yielded this (from Wikipedia):

“The genus name Philaenus comes from the Greek philein (“love”), while the species name spumarius is from the Latin spuma (“sparkling”), referred to the foam nests; the binomial Philaenus spumarius can be translated as “foam lover.”

The adult spittlebug is small (approximately 6mm in length). Both adults and nymphs (which go through 5 instars or developmental stages before reaching adulthood) feed on plant xylem and have been found to feed on over 450 species of plants (2,3,4). While they have the ability to transmit viruses and cause damage to plants from feeding, they are typically not considered serious pests unless they are present in large numbers. It was interesting to learn that the nymphs consume up to 280 times their own weight of plant sap in 24 hours (2,3,4).

Also interesting is that only the soft-bodied nymphs live in the foam. It provides them with protection from predation and from drying out (desiccation). The spittle is a fluid produced from their anus and combined with a surfactant secreted by epidermal glands near the end of their abdomen. Caudal appendages on the insect create air bubbles, turning the spittle into a frothy foam. The tiny (1/4″ long) spittlebug nymph usually rests on the plant facing downward. When the spittle is produced, it flows downward over the body and covers the nymph, concealing it and providing it with the moist habitat it requires as it develops (4).

Another interesting bit about the Meadow Spittlebug is that it is quite polymorphic with no less than 16 adult color forms (1). Andy Hamilton (2006) has contributed a wonderful chart, shared on Bugguide https://bugguide.net/node/view/72602 to illustrate the color varieties of the adult forms of this highly variable species (1, 2). Because of the diversity among adult specimens within this species, many researchers have been interested in Philaenus spumarius for genetic study (4).

*I wanted to include a personal observation about natural enemies of spittlebugs. Hamilton (1982) gives the most detailed account of these, but I didn’t note any mention of predation by yellow jackets (Hymenoptera: Vespidae), or dragonflies (2). I have observed both of these flying through meadow grasses appearing (but not confirmed) to glean spittlebugs from plants in early summer on San Juan Island.

References:

1. Bugguide.net https://bugguide.net/node/view/7452

2. Hamilton, K.G.A., 1982, The spittlebugs of Canada: Homoptera: Cercopidae, Insects and Arachnids of Canada Handbook Series, 10, 102 http://esc-sec.ca/publications/aafc/

3. Horsfield, D., Evidence for xylem feeding by Philaenus spumarius(L.) (Homoptera: Cercopidae). Ent. Exp. Appl., 24: 95-99, 1978.

4. Yurtsever, Selcuk. (2000). On the meadow spittlebug Philaenus spumarius. Turkish Journal of Zoology. 24. 447-459.