What is causing these spit-like blobs on my grape vines?

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Question What is causing these spit-like blobs on my grape vines?

Answer These dripping, slimy hunks of foam are formed by an insect appropriately known as the spittle bug. Baby (or nymph) spittle bugs developed this system as a form of protection. They don't sit in trees and try to spit on unsuspecting people passing by. Instead, they are hiding out in that wad of spit. This spit ball serves as a great form of protection. Predators can't see through it and it prevents pesticides from hitting the baby spittle bugs.

If this whole situation is not nasty enough for you, the wad of spit is not really spit. The nymph sucks juices from the plant. “Spittle” is then secreted from the baby bug's butt. It flows down over its body and mixes with excretion from glands on the seventh and eight abdominal segments (secret ingredients). Periodically, they stick the tip of their abdomen up, suck in some air and blow bubbles. This process forms a foamy mass that hides and protects the baby bugs. Let’s just say their name reflects its appearance and not the true ingredients. Would shizzle bug be more memorable?

Adult spittle bugs don’t need a spit ball since they can jump over two feet. Last year, the spittle bug leaped past the flea as nature's most powerful jumper. It not only jumps twice as high, it accelerates 10 times faster than the flea. That speed on such a small body subjects the bug to 400 times the force of gravity (or 400 Gs). Pilots diving through the sky in a fighter plane occasionally reach 10 Gs, but they need a pressure suit to survive.

In the spring, spittle bugs are commonly found on junipers and pines. They inflict little damage on mature plants. However, when they feed on bunch grapes (not muscadine), they have the potential to vector (deliver) the bacterium Xylella fastidiosa. This bacterium is also known as Pierce’s Disease. In warm climates, Pierce’s Disease is the number one killer of bunch grapes. This disease is also the reason bunch grapes are best grown in the mountains. For more info on Pierce’s Disease, visit http://arecs.vaes.vt.edu/webinfo/files/PD3.pdf

The best "control" of spittle bugs is to tolerate the situation until they mature in a few weeks. If action is required, spraying the plants with a water hose is usually sufficient (may have to repeat two to three times). Hand picking insects is also an option (yeah right). No insecticides are recommended because the bugs are protected by the spittle.

For more info about spittlebugs, visit http://www.hort.wisc.edu/mastergardener/Features/insects/spittlebug/spittlebugs.htm If you don’t have internet access, then call me at 910-893-7533 or email me at gpierce@harnett.org

If the spittle in your shrubs is brown, then you may have a Beechnut problem.

Gary L. Pierce

Horticulture Extension Agent

Harnett County