Derbid Planthopper - Anotia bonnetii

These spittlebugs are resident on common thistle, Cirsium sp.

Spittlebugs get their name from the blobs of frothy "spit" concocted by their nymphs and deposited on plants where they feed. The nymphs hide inside the froth, which provides cover, temperature regulation, and protection against desiccation. Like many bugs, spittlebugs feed on plant sap. [2]

The nymphs feed head-downward on the plant, and excess fluid taken in is mixed with substances that increase its viscosity. The fluid is forced out of the bug's anus under pressure, creating air bubbles which pile up onto the insect's back. Unlike most other bugs, spittlebug nymphs suck fluid from the xylem, which is the main water-carrying structure of the plant. Since the nutrients are more dilute in fluid pulled from the xylem, spittlebugs are frequently found on nitrogen-fixing legumes that have a high concentration of amino acids in their sap.

In addition to legumes, spittlebugs are found on many grasses, roses, Chrysanthemums, daisies and goldenrod. The meadow spittlebug also feeds on a wide range of plants including alfalfa, clover, strawberries and many other garden plants. [3]

Description
The adults are heavy-bodied, wedge-shaped insects about a quarter of an inch long. They are usually a mottled brown and cream, but vary from cream to almost black. They jump readily, making an audible thump. The eggs are small, yellow-to-white, elongate capsules laid in rows in a matrix under the leaf sheaths of grain stubble and in similar places. The young (nymphs) are yellow to orange. The nymphs cause the damage. They are found behind leaf sheaths, in folded leaves, or on the leaves and stems in masses of froth or spittle during late April, May, and early June. Both the nymphs and the adults may be found on a wide variety of weeds and plants, but they concentrate chiefly in alfalfa and clover fields.

Life Cycle
There is one generation each year. The insect overwinters in the egg stage. The eggs hatch in early to mid-April in central Illinois, and the last two weeks in April in northern Illinois. After the tiny nymphs hatch, they immediately start to suck sap from the plant and form the froth in which they live. At first, they are found in the crowns and the folded leaves of the plants; later, in large masses of froth anywhere on the plant. From one to several nymphs may be found in a mass of froth. The nymphs mature in June. The adults feed on a variety of plants until late August, when they congregate in clover and alfalfa fields to lay their eggs. Egg-laying continues through September.

Damage
When abundant, spittlebugs stunt plant growth by sucking the sap. They may cause losses in yield varying from slight to 25 percent or more. An average of 1 nymph per stem can decrease the yield of dry hay by 300 or more pounds per acre. To determine the need for treatment, count the spittlebugs on 50 to 100 stems selected throughout the field. [2]

Control
Meadow spittlebug infestations cannot be controlled the year they occur. Heavily infested fields (50 to 100 spittle masses/plant) should be sprayed in September to kill adults and thereby reduce the nymph population the following spring. A follow-up spray in the spring should be directed toward the young, unprotected nymphs. [3]

References

Bugguide.net, Philaenus spumarius (Meadow Spittlebug)
University of Illinois Integrated Pest Management, Meadow Spittlebug Philaenus spumarius
National Science Foundation, Center for Integrated Pest Management, Meadow Spittlebug
Dr. Jo-Ann Bentz, United States National Arboretum, Floral and Nursery Plants Research Unit, Management of Insect Pests of Ornamental Trees and Shrubs

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