Buffalo treehopper—Stictocephala alta =S. bisonia
This treehopper (family Membracidae) sucks and feeds on various herbaceous and woody plants. There are at least 40 species of treehoppers in California.
Adults of buffalo treehopper are brown or green and 2/5 inch long or shorter. Viewed from above, adults have a triangular shape. They have an expanded first segment behind the head (pronotum) that forms a hoodlike covering on top the front one-half of their body. This enlarged prothorax distinguishes treehoppers from most other true bugs (Heteroptera) they resemble.
Treehoppers also have rows of spines along the length of the hind tibia (longest leg segment), as do also cicadas and leafhoppers. To help you discriminate between types (families) of insects with similar-looking adults see Distinguishing Among Sucking Insects That Resemble Each Other.
Eggs are 1/16 inch long and occur hidden laid in twigs. First instars are about 1/12 inch long. Nymphs are reddish brown with numerous spines on the back of the abdomen. The nymphs commonly occur in groups on plant stems, especially the younger immatures. Both immatures and adults jump readily when disturbed, such as when they observe movement nearby.
Treehoppers develop through three life stages: egg, nymph, and adult. They overwinter as eggs that are laid in groups in slits that females make in the upper side of twigs. Eggs hatch in spring and the nymphs drop to feed on herbaceous vegetation near where they overwintered as eggs. Adults occur during summer and fall, when the females lay the overwintering eggs. There is one generation per year.
Treehopper adults and nymphs suck plant juices. This feeding generally causes no noticeable damage to woody hosts. The honeydew they produce supports the growth of blackish sooty mold, which may foul leaves and stems and surfaces underneath them when treehoppers are numerous. The egg laying slits made in small, woody twigs can give bark a roughened appearance. Egg laying injury sometimes stunts terminal growth or slows the overall growth of young hosts.
Generally no control is warranted to protect the health of hosts. Eliminating herbaceous weeds can reduce the survival of nymphs and the subsequent abundance of adults, thereby reducing their egg laying damage to twigs. On small plants buffalo treehopper can be controlled somewhat with a forceful spray of water.
If treehopper populations were high on deciduous trees and shrubs the previous season and damage cannot be tolerated, horticultural (narrow-range) oil can be applied to thoroughly cover terminals during the dormant season to kill overwintering eggs. If adults or nymphs are abundant, their numbers can be reduced by spraying the exposed insects with horticultural or narrow-range oil or insecticidal soap (potassium salts of fatty acids).
Adapted from Pests of Landscape Trees and Shrubs: An Integrated Pest Management Guide, University of California Statewide Integrated Pest Management Program (UC IPM).
Adult buffalo treehopper.
Adult buffalo treehopper shown from above.
Adult buffalo treehopper.
Nymph of buffalo treehopper.