Being a Landscape Designer in Santa Clarita means that people come to me with questions about plants, design, and even pests. Recently a friend called to ask me what the foamy stuff was on her rosemary plants, and my answer of course was Spittle Bugs. It got me to thinking that in this hot weather with the over use of irrigation there were probably a bunch of people in SoCal asking themselves the same question.
Though Spittle Bug’s foam look unsightly they really do very little damage to a home gardener’s plants because they are very inefficient eaters, they suck sap from your plants but usually not enough to really hurt them. Large infestations however can adversely effect your plants especially large scale crops, so take care of the problem early and you’ll be fine.
The foam that you see is generally all you’ll ever see of the spittle bug, and it is there to hide the adult and it’s immature babies. You’ll most often find it where two branches meet or where a leaf and a stem join.
The mature spittle bug looks like a moth, but in reality it is more closely related to the cicada or aphid and like the aphid (as mentioned above) it sucks the sap from the plants. In California I have mostly seen them on Rosemary plants but they also affect legumes, strawberries, junipers, pine trees and alfalfa.
For home gardeners the best defense against these plants is to simply spray off the plants with a strong stream of water. Yes, early detection helps and it can be that easy.
So next time you see that unsightly foam on your plants, just take out the hose and spray!