Philaenus spumarius Linnaeus
Appearance and Life History
The meadow spittlebug, easily identified in the nymphal stage within its spittle mass, is a common early-season pest of alfalfa and clover. Damage is generally most severe following the establishment of alfalfa in small grain stubble.
First cutting alfalfa is occasionally damaged by heavy infestations of meadow spittlebug nymphs. The nymphs are orange and about 1/25 inch (1 mm) long when they first hatch, gradually becoming green and about 1/4 inch (6 mm) long as they mature. Throughout all five instar stages, the nymphs live within a frothy mass which they secrete. This frothy substance resembles spittle. Spittle masses may be found in alfalfa fields through the spring and early summer.
The adult meadow spittlebug emerges in late May and early June. They are yellowish-brown to dark brown insects that have short blunt heads with prominent eyes. This frog-like appearance has resulted in their being referred to as "froghoppers." Their wing covers are held tent-like over their bodies and are marked by dark spots, stripes, or bands. Egg laying begins in mid August. Eggs are laid in masses in a frothy cement between the plant's sheath and stem.
Meadow spittlebug nymphs suck juices from alfalfa plants with their piercing-sucking mouthparts. Large numbers of nymphs may cause plants to be stunted, resulting in yield loss. Damage is usually heaviest on first-year alfalfa following establishment in small grain stubble.
Adult spittlebugs do not damage alfalfa. There is only a single generation each year, alfalfa is no longer threatened by this insect once adults emerge.
When a substantial number of spittle masses are found in young alfalfa [usually less than 6 inches (15.2 cm) in height], sample to determine the extent of the infestation. Walking the field in a M-shaped pattern, count the number of spittlebugs within 1 square foot (30 cm square) in at least 10 locations per field. A single mass may contain 1 to 25 or more spittlebug nymphs, so it is important to separate the nymphs from the spittle when counting. Calculate the average number of meadow spittlebug nymphs per square foot.
Forage Insect Control Recommendations: E-series 220-W (PDF)
Use the charts below to determine when it is economical to control spittlebugs. The charts are based on 3 grower management levels for the first cutting (i.e., 1, 2, and 3 tons of hay per acre) and 4 alfalfa hay values (i.e., $60, $80, $100, and $120 per ton).
As one would expect, these charts indicate that as the value of alfalfa increases, it becomes more economical to treat for spittlebugs. Expected yield also plays a role in determining the economics of treating for meadow spittlebug. With an expected yield of 1 ton per acre, the value of alfalfa hay would have to be at least $100 per ton to realize an economic return from treatment of even extremely high spittlebug populations [i.e., 150 nymphs per square foot (30 cm square)]. On the other hand, at an expected yield of 3 tons per acre, you might anticipate an economic return from treatment of populations as low as 10 nymphs per square foot (30 cm square), even when the crop is valued at only $60 per ton. Consequently, it is important to know not only the spittlebug infestation level, but the value of the hay, the expected yield, and the cost of purchasing and applying an insecticide when determining the need for control.
Use the chart as follows:
- Select the appropriate chart for the value of your alfalfa.
- Locate, along the bottom of the chart, the average number of spittlebug nymphs found per square foot (30 cm square).
- Draw a vertical line from your spittlebug population level to intersect with the line for your expected yield per acre.
- Draw a horizontal line to the left margin to determine the affordable cost of control.
- Compare the cost of the insecticide plus application per acre with the affordable cost from the chart. Treat if the actual cost is equal to or less than the cost read from the chart. If the actual cost is greater than that on the chart, resample in 3-5 days to determine if the spittlebug nymph numbers increase, and proceed through the decision-making process again.
NOTE: When alfalfa is sampled and only first and second stage nymphs are found without the present population being at economic levels, sampling should continue at weekly intervals. Hatching continues over a prolonged period and the economic threshold may not be reached until the peak of the third nymphal stage (half-grown nymphs).
If control is necessary, contact your state Cooperative Extension Service or click here for control materials and rates.