Foam On Your Pine Trees?

The pine spittlebug (Aphrophora parallela) is a fascinating insect that, while generally not severely damaging to trees, can occasionally cause concern for tree owners. This unique creature is known for its distinctive habit of producing frothy "spittle" masses, which serve as a protective covering for its nymphs.

Host Plants and Life Cycle

Pine spittlebugs prefer several coniferous species as their hosts, including:

• Eastern white pine
• Scotch pine
• Jack pine
• Austrian pine
• Spruce species
• Fir trees

The life cycle of the pine spittlebug begins in spring when nymphs hatch from eggs laid under the bark of shoots the previous summer. From May to early July, these nymphs feed on the tree's sap and produce their characteristic frothy spittle masses. This feeding and spittle production stage lasts for about six to seven weeks.

Appearance and Behavior

Adult pine spittlebugs, which emerge in July, are tan to dark reddish-brown and about 3/8 inch long, resembling chunky leafhoppers. While adults continue to feed on the tree's sap, they no longer produce spittle masses.

Impact on Trees

In most cases, pine spittlebugs cause minimal damage to their host trees. Their feeding typically results in:

• Discolored branch tips
• Slightly deformed branches
• Needle browning (flagging)

However, heavy infestations can lead to more serious consequences:

• Twig and branch mortality
• Stunted growth
• In rare cases, whole tree mortality after 2-3 years of severe infestation

Associated Risks

One of the more significant concerns associated with pine spittlebugs is their potential to create entry points for Diplodia tip blight, a fungal pathogen. This fungus can invade the tree through the feeding punctures made by the spittlebugs, potentially causing more severe damage than the insects themselves.

Control Measures

If pine spittlebugs become excessively abundant on a tree, control measures may be necessary. A foliar spray applied between mid-June and mid-July can effectively manage the population.

Despite their potential to cause damage, pine spittlebugs remain an intriguing part of our landscape ecosystem, showcasing nature's diverse and often unusual survival strategies.

Pine spittlebug on spruce tree. Photo: William M. Ciesla, Forest Health Management International, Bugwood.org