Insect Management in South Florida Pastures

September, 2013
Les Baucum; UF/IFAS Regional Extension Agent III

Our most common insect pests in south Florida pastures are typically mole crickets, spittle bugs and different caterpillar larval complexes.  This article will discuss these pests and other occasional pest we find in our forage grasses.   

Mole Crickets

Mole cricket damage is usually associated with bahia pastures but is occasionally seen in other forage species as well.  In Florida there are two species of mole crickets that are responsible for economic damages to forages and pastures; the tawny mole cricket and the southern mole cricket.  Usually the first sign of mole crickets that you will notice is the occurrence of tunnels near the soil surface; this burrowing will loosen the soil and can resemble tiny mole tunnels.  If you have ever seen a mole cricket they are easily identified; adults are about 1½ inches long, tan to greyish-brown in color with forewings that are shorter than their abdomen and front legs that are flattened for digging.

Mole crickets typically mate once a year, during the spring; beginning in March mated females will typically lay anywhere from 100-175 eggs each with the peak egg laying months being May and June.  Eggs will hatch in about 20 days, the young mole crickets are called nymphs; most damage is caused by these nymphs who will feed on the plant roots until fall when they will reach adulthood.  Extensive root feeding can lead to large areas of wilted and dead forage grasses; large populations can lead to extensive forage losses and ultimately require a pasture renovation.

There are multiple biological control methods that have proven to have some control of mole crickets. The mole cricket nematode was evaluated by the University of Florida and has been shown to have some control of late instar nymphs and adult mole crickets in Florida.  These nematodes have been produced commercially, but can sometimes be hard to find; additionally it is important that correct application methods be followed to get effective control.  In addition to nematodes there are two different parasitic flies that have been proven to parasitize mole crickets.  These wasps are established in several counties in Florida and in some areas have provided adequate control.  Chemical control methods for heavy infestations have proven to be largely ineffective.

Mole crickets can be hard to “scout” for and typically we would use historical knowledge of past infestations to locate problem areas.  To confirm the presence of nymphs and adults you can use a 2% soapy solution as a soaking agent, pour generously over approximately a 3 foot square area to bring any mole crickets to the surface.


Spittlebugs will feed on a wide range of forage grasses and are often found in bermudagrass, limpograss and stargrass pastures.  Adults of the two-lined spittlebug have a characteristic leafhopper shape, they are dark brown to black with red legs and eyes and it has to conspicuous red to orange lines running across its wings.  The nymphs (or immature spittlebugs) are cream-colored with brown heads and eyes.  The nymphs produce a frothy white mass that completely hides them and acts as a protectant as they feed.

Spittlebugs overwinter in the egg stage in hollow stems and in heavy thatch at the base of plants.  As the temperatures warm these overwintered eggs will begin hatching, typically in March or April.  The young spittlebugs, or nymphs, will begin feeding immediately and will feed for 30-50 days before becoming an adult.  On average an adult female will lay 45 eggs, there are 2 and sometimes 3 generations of spittlebugs per year with the adult spittlebug population peaking in August.  Adults and nymphs damage grasses by inserting their tiny needle like mouth parts into the plant and feeding off of the plant juices.  Adult spittlebugs will inject plant toxins into the plant during this feeding process and cause streaking or stippling type symptoms.

The presence of spittlebugs can be easily confirmed by the mass of froth or spittle like material the nymphs produce for protection.  There are no known biological control agents for spittlebugs and no pesticides are currently registered for control of spittlebugs on pastures.  Applications of carbaryl insecticides for other pests sometimes will suppress an existing adult spittlebug infestation, but is ineffective on populations of nymphs because the spittle mass acts a barrier keeping the pesticide from actually reaching the young spittlebugs.  The most effective cultural control of spittlebugs would be to burn off pastures in February or March in order to kill any overwintering eggs that are laid in the heavy thatch cover.


In Florida we have three species of armyworms that are found in forages; the southern and yellowstriped armyworms are considered occasional pest of forage grasses with the fall armyworm being the species that causes the most serious damage.  Adult fall armyworm moths are about ¾ inch in length with gray scales with lighter markings. They have a distinct light colored stripe along the front edge of the mid-forewing.  Female moths lay eggs on lower leaf surfaces in masses of 100-150 eggs and cover them with scales; on average a female will lay 3-5 of these egg masses.  The newly hatched larvae are about 1/16 inch long, their soft bodies are light green to cream colored and they have a dark head capsule.  As they grow they become darker in color with distinct light colored lines along the sides of their bodies.  Larger larvae have a dark head capsule with a lighter colored inverted Y mark on the front.  They pupate in the thatch at the soil level; they are dark in color and about 5/8 inch long.

The fall armyworm will survive most winters in central and south Florida; during extremely cold winters survival may be limited to extreme south Florida.  Moths are very strong flyers and are capable of re-infesting north Florida by early spring.  There are several hundred wild and cultivated plants that make suitable host for the fall armyworm including important crops such as corn, cotton and peanuts among others.  Damage is caused by the feeding of the armyworm larvae.  The larval stage will last 12-16 days, with last instar larvae being about 1½ inches long.  Early instar larvae feed along leaf edges and molt every 1-2 days, later instar larvae may consume the entire leaf blade and molt about every 4 days.  As a result about 90% of the food consumed is eaten during the last two instars. 

Striped Grass Loopers

Striped grass looper larvae are frequently found in mixed populations with fall armyworm larvae.  They prefer bermudagrass and stargrass but in high populations can cause economic damage to most species of grass.  Loopers are easily distinguished from armyworm species by the number of abdominal prolegs; grass loopers have two pairs of abdominal prolegs while armyworms have four pairs.  The body of the larvae is covered with black and white spots with light colored narrow stripes along the middle of its back.  They can range in color from cream to orange to nearly black. The head capsule will have numerous vertical lines.

There are several generations of loopers each year in Florida.  Early instar larvae begin feeding by stripping the epidermis from the top surface of the leaf, which gives the plant a brown ragged appearance and inhibits photosynthesis.  When the larvae are about half grown they begin feeding on leaf margins, and will consume the entire leaf blade, leaving nothing but the occasional midrib.  After the larvae feed for approximately three weeks they will move to a protected area in the canopy, fasten several blades of grass together and spin a cocoon where they will pupate for 8-10 days before emerging as adults.

Monitoring for Larval Pests

Monitoring sites are typically a 1 foot by 1 foot area; you should inspect at least 10 of these one square foot sites per field.  If only a few fields are to be sampled it is ok to estimate your 1 foot by 1 foot sample area.  However if there are a lot of samples to be taken it is easier to use a 1 foot by 1 foot sampling frame (which can easily be made out of pvc or other easily obtained materials).  Before disturbing the area to be sampled you should examine the surface and the edge of the leaf blades for signs of feeding damage.  If you do not find feeding damage the chances are very good that if any larvae are found they will be small.  To continue your inspection of your one square foot sample site examine the leaf blades, stems and organic debris at the base of the plant and the soil surface.  Count the number of larvae within the sample area and record their size as less than ½ inch in length or greater than ½ inch in length.  While it is typical that you would have a mixed size of larvae across your samples, management decisions are more often than not based on the number of larvae present that are less than ½ inch in length.  Larvae greater than ½ inch in length are nearly full grown and are near the end of their feeding period, conversely larvae less than ½ inch in length have a longer period left before they pupate and thus more feeding potential.  After all of the samples have been taken, calculate the average number of small and large larvae per sample site.  If the field has not been previously treated then chemical control is justified if averages of 3-4 small larvae per sample site are found.  If the field has been treated then chemical control can be justified if averages of 2 small larvae per sample site are found.

Other Insect Pests

Aphids: Two species of aphids can cause occasional damage to Florida forages. The sugarcane aphid is a pale yellowish in color; it prefers pangolagrass and is most common in south Florida.  The second species, the greenbug, is pale green with a dark green stripe down its back, although it is found throughout the state its natural enemies usually keep the populations at low levels and it is generally not associated with economic damage.

Mites: There are several species of mites that feed on forages in Florida but the most common are the banks grass mite and the Bermudagrass mite.  Mite damage can first appear as yellow flecks along the grass blades, yellowed leaves, stunted growth , eventually leaves can become straw colored and may eventually whither and die.

Bermudagrass Stem Maggot:  Is a new invasive pest in the southeastern United States. There is very little information on this insect, its life cycle or the amount of damage to expect if insect populations continue to increase. It is believed that the adult fly lays its eggs on the pseudostem, where upon hatching the young larvae migrate to the leaf nodes and begin feeding.  Damage can range from yellowing and chlorosis of the top leaves to leaf death. Currently there is little information on effective control methods.

The above list represents only the most commonly encountered problems; others such as grasshoppers, white grubs, scale insects and mealy bugs can be occasional pests of forages.  For best control options consult with your local County Extension Agent.

Reference: Sprenkel, Richard and Eileen A. Buss; Insect Management in Pasture; UF/IFAS EDIS Publication #ENY-402; 8 pages.

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