Fireweed blooms hindered by foam?

Observation by Julia Salt:

Foam or saliva-looking substance on seen on flowering plants like fireweed and yarrow. In fireweed, this is causing some of the flowering section to silt to the side. In some cases the location of the foam is at the tallest part of the plant and is preventing flowers from forming. On yarrow, they don't appear to be affecting the growth of flowers because the foam is underneath the flowers.

LEO Network says:

Thank you Julia for your observation. We have received similar observations from members who have noticed this interesting foam attached to different plants, including fireweed (see attached); two in Alaska and one in Ireland. Spittle bug is a likely cause for the foam. How spittlebug foam may effect the condition of the fireweed bloom (or other plants) is a good question. According to guidance provided by the University of Minnesota Extension Service on Spittlebugs in Home Gardens (see attached) spittlebug feeding and foam generally does not have much of an impact on plant health. "In most cases, especially on annuals and perennials, spittlebug feeding is not damaging to plants. If too many spittlebugs are present, feeding can cause leaves to lose their shape." Perhaps what was happening with these fireweed blooms. If you want to remove spittle from plants, you can simply wipe it off or spray with water. For more on Spittlebugs, see the description provided below by Chyna Williams in a previous LEO Network post. Mike Brubaker

According to the publication Insects and Diseases of Alaskan Forests, Spittlebugs aka Froghoppers are distributed in Southeast and southcentral Alaska. They can be found in most of the continental US states in any plant environment. The plant species that host them are sitka spruce seedlings, hardwoods, and ground vegetation. their biology is not well known in Alaska, but they can be identified through the following description: "Both the adult and nymph feed on plant fluids; only nymphs make spittlemass that serves as a protective covering. Young nymphs are red and black; older nymphs are brown. Adults are brown to black and similar to nymphs but with wings. Eggs are teardrop in shape."

The spittle they produce is created through a abdominal opening which secretes a mixture of liquid waste. Unlike other insects that feed on the sugary phloem of plants, Spittlebugs drink the xylem that has much more water content. Because of excess water ingested, these bugs secrete the foam. They utilize the foam to protect themselves from parasites and predators, and it gives them much-needed moisture control, without which they would quickly die. C. Williams