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ENY-324 Pest Mole Cricket Management 1 E. A. Buss, J. L. Capinera, and N. C. Leppla2 1. This document is ENY-324 (LH039), one of a series of the Department of Entomology and Nematology, Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida. Date first printed October 1993. Revised: June 2006. Please visit the EDIS Website at http://edis.ifas.ufl.edu. 2. E. A. Buss, assistant professor, J. L. Capinera, department chairman, and N. C. Leppla, professor, Department of Entomology and Nematology, Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida, Gainesville, 32611. The use of trade names in this publication is solely for the purpose of providing specific information. UF/IFAS does not guarantee or warranty the products named, and references to them in this publication does not signify our approval to the exclusion of other products of suitable composition. All chemicals should be used in accordance with directions on the manufacturer's label. Use pesticides safely. Read and follow directions on the manufacturer's label. The Institute of Food and Agricultural Sciences (IFAS) is an Equal Opportunity Institution authorized to provide research, educational information and other services only to individuals and institutions that function with non-discrimination with respect to race, creed, color, religion, age, disability, sex, sexual orientation, marital status, national origin, political opinions or affiliations. U.S. Department of Agriculture, Cooperative Extension Service, University of Florida, IFAS, Florida A. & M. University Cooperative Extension Program, and Boards of County Commissioners Cooperating. Larry Arrington, Dean Three species of mole crickets were detected in the southeastern U.S. about 1900, and are now serious plant pests. Those species are the tawny mole cricket, Scapteriscus vicinus (Figure 1), southern mole cricket, S. borellii (Figure 2), and shortwinged mole cricket, S. abbreviatus (Figure 3). Other, non-damaging mole crickets occur in North America (e.g., Neocurtilla hexadactyla), but these three are the most damaging. Figure 1. Tawny mole cricket adult. Credits: L. Buss, University of Florida Figure 2. Southern mole cricket adult. Credits: L. Buss, University of Florida Figure 3. Shortwinged mole cricket adult. Credits: L. Buss, University of Florida Host Range Though usually considered turfgrass pests, Scapteriscus spp. mole crickets have a broad diet. The
Pest Mole Cricket Management 2 southern mole cricket feeds mainly on other insects, and the tawny and shortwinged mole crickets feed on plants. Commonly injured plants include tomato, strawberry, beet, cabbage, cantaloupe, carrot, cauliflower, collard, eggplant, kale, lettuce, onion, pepper, potato, spinach, sweet potato, turnip, chufa, peanut, sugar cane, tobacco, such flowers as coleus, chrysanthemum, and gypsophila, as well as weeds such as pigweed. The tawny mole cricket often injures bahiagrass and bermudagrass, and the shortwinged mole cricket often attacks St. Augustinegrass and bermudagrass. Damage Mole crickets can damage plants by feeding at night on aboveground foliage or stem tissue and belowground on roots and tubers. Seedlings may be girdled at the stems near the soil surface, though some plants may be completely severed and pulled into a tunnel to be eaten. Mole cricket tunneling near the soil surface (Figures 4, 5) dislodges plants or causes them to dry out. Small mounds of soil are also pushed up. Tunneling reduces the aesthetic quality of turfgrass, interferes with the roll of the ball on golf courses, and results in reduced livestock grazing on severely infested pastures. Figure 4. Mole cricket tunneling in dirt. Credits: E. A. Buss, University of Florida Figure 5. Large area of mole cricket tunneling. Credits: E. A. Buss, University of Florida Life Cycle The southern and tawny mole crickets are similar in appearance and biology. The shortwinged mole cricket is different because its short wings prevent flight, and males have no calling song. Typically, the eggs of these three species are laid in April-May, and nymphs occur through August. In southern Florida, however, the shortwinged mole cricket can produce eggs throughout the year. Some adults occur in August or September, but both nymphs and adults overwinter. Overwintering nymphs become adults by April, and adults fly and mate. One generation per year is normal, though in southern Florida southern mole crickets have two generations and fly three times (spring, summer, and autumn). Due to temperature differences, adult southern and tawny mole crickets emerge earlier in the year in southern Florida than in northern Florida. Description Eggs: About 25-60 eggs per clutch are laid in a chamber in the soil. The chamber can be 5-30 cm below the soil surface, and measures 3-4 cm in length, width, and height. Egg development lasts about 3 weeks, depending on soil temperature. Females may lay up to 5 clutches of eggs before dying. Nymphs: Nymphs hatch from eggs from April to June. Nymphs resemble the adults, but their wings (wing pads) are not completely developed. The number of instars is variable, probably 8-10. Adults: Mole crickets have enlarged forelegs that they use to dig in soil (Figure 6). The forelegs have large blade-like projections, called dactyls, and the number and arrangement of dactyls, and the pronotum pattern are used to identify different species (Figure 7).
Pest Mole Cricket Management 3 Figure 6. Mole cricket anatomy. Figure 7. Key traits used to identify Scapteriscus spp. mole crickets. Tawny and southern mole cricket males attract females by producing a courtship song from their burrows early in the night. Mating and dispersal flights occur in spring, from late February to April. Tawny mole crickets look similar to southern mole crickets, with moderately long forewings and long hind wings, a yellowish brown body, and a dark pronotum with a central band. Dactyl spacing distinguishes between the two species. The dactyls nearly touch at the base, like the shape of a "V". The tawny mole cricket's calling song occurs during the first 90 minutes after sunset. Southern mole crickets have long hind wings that extend past the abdomen and are rounded at the tips. Adults are brownish-gray with a dark pronotum. The dactyl spacing is similar for shortwinged mole crickets (looks like a "U"), so these two species can best be distinguished by wing length. The southern mole cricket's calling song occurs during the first two hours after sunset. As a predator, the southern mole cricket is more active and tunnels more than the tawny mole cricket. Shortwinged mole cricket adults are 22 to 29 mm long, with wings shorter than the pronotum (area behind the head). The body is mostly tan in color, but the pronotum is brown mottled with darker spots. The top of the abdomen has a central row of large spots, and smaller spots to either side. Dactyl spacing looks like a "U". Shortwinged mole cricket males have no calling song. Management Sampling Several methods are used to estimate mole cricket populations and assist in timing pesticide applications. One way is to rate the amount of tunneling damage that is visible. Tunneling is most obvious in low-cut grass or areas with minimal vegetation, and thus can be detected easily in crops, bahiagrass lawns and pastures, or bermudagrass fairways.The tunnels are most visible in early morning, when the dew is on the grass and the soil may be moist. A more consistent but labor intensive method of sampling is a "soap flush." Flushing is more effective in moist soil. Mix 1.5 oz (2 TBSP) of lemon liquid dishwashing soap in 2 gal of water in a sprinkling can, and pour the solution onto 3-4 sq. ft. of turf. If two to four mole crickets emerge within 3 minutes after applying the soap solution, insecticide use may be justified. Flushing with a synergized pyrethrin insecticide solution is equally effective. Adult females can also be captured at night with commercially available electronic sound traps that mimic male mating songs. In addition, adult mole crickets are strongly attracted to lights during their spring dispersal flights. Biological Control Mole cricket natural enemies do exist naturally in North America. Among the natural enemies are amphibians (e.g., toads, Bufo spp.), birds (e.g., sandhill cranes, Grus canadensis), and mammals
Pest Mole Cricket Management 4 (e.g., armadillos, Dasypus novemcinctus). They, and the few predatory insects that attack crickets such as tiger beetles, are not effective. Thus, several natural enemies have been introduced from South America. A parasitic wasp, Larra bicolor (Figure 8), was imported from South America in the 1980s and released, and has since spread in Florida. Another parasitoid, the red-eyed brazilian fly, Ormia depleta (Figure 9), was released in 1988. It is attracted to the mating calls of male mole crickets. Figure 8. Mole cricket adult parasitized by Larra bicolor. Credits: L. Buss Figure 9. Ormia depleta adult. Credits: L. Buss, University of Florida Biological control of mole crickets can be enhanced by applying the entomopathogenic nematode, Steinernema scapterisci (Figure 10), or possibly other entomopathogenic nematodes. Steinernema scapterisci was introduced from Uruguay in 1985. It infects only Scapteriscus spp., persists readily in Florida's climate, and is dispersed by mole crickets. Infected mole crickets die within 2 weeks. This nematode (Nematac S) can be purchased from commercial suppliers (Lesco, Prosource One, UHS, Gardens Alive, and others), sprayed as a suspension in water to soil, and is fairly persistent in the soil. It is more effective when applied to adults and large nymphs in the spring or fall. Figure 10. Mole cricket infected with the nematode, Steinernema scapterisci. Credits: L. Buss, University of Florida Insecticides Liquid and granular formulations of insecticides are commonly applied to the soil to suppress newly hatched mole cricket nymphs (Table 1) from April to June. Irrigating before an insecticide application may drive mole crickets closer to the soil surface, and helps the pesticide to penetrate into the soi. Some insecticides should be watered in after application to move them into the root zone of the plants where the mole crickets are feeding. However, it is essential to read and understand the insecticide label carefully for application directions. Bait formulations are useful against larger nymphs in late summer. Mole crickets feed at night, so baits should be applied in the early evening. Baits are incompatible with irrigation and rainfall. Additional information is available on the Mole Crickets web site: (http://molecrickets.ifas.ufl.edu/ mcri0001.htm) (http://molecrickets.ifas.ufl.edu/) and the IPM/Biological Control web site: (http:// biocontrol.ifas.ufl.edu).
Pest Mole Cricket Management 5 Table 1. Insecticides labeled for professional use against mole crickets in Florida. Active Ingredient Florida Registered Products Chemical Class Signal Word Acephate Acephate Pro 75 Organophosphate Caution Orthene Turf, Tree & Ornamental Spray Caution Bifenthrin Talstar GC Flowable*, Granular*, EZ Pyrethroid Caution Talstar Lawn & Tree Flowable, PL Granular Caution Carbaryl Parkway's Mole Cricket Bait Carbamate Caution Clothianidin Arena Neonicotinoid Caution Cyfluthrin Tempo 2 EC Pyrethroid Warning Tempo 20 WP, SC Ultra Caution Deltamethrin DeltaGard GC*, T&O Pyrethroid Caution Fipronil Chipco Choice Phenylpyrazole Caution Top Choice Caution Imidacloprid Merit 75 WP, 0.5 G Neonicotinoid Caution Indoxacarb Advion Mole Cricket Baitt Indoxacarb Caution Lambda-cyhalothrin Battle GC T&O* Pyrethroid Caution Scimitar CS, GC* Caution Permethrin Permethrin Pro-Termite T/O Pyrethroid Caution Steinernema scapterisci Nematac S Biopesticide Caution Trichlorfon Dylox 6.2 G Organophosphate t Caution Dylox 80 T&O Warning = Restricted Use Pesticide Table 2. Insecticides labeled for homeowner use against mole crickets in Florida. Active Ingredient Florida Registered Products Chemical Class Signal Word Bifenthrin Ortho Ortho-Klor Termite and Carpenter Ant Killer Pyrethroid Caution Scotts Turf Builder with SummerGuard Caution Cyfluthrin Bayer Advanced Lawn & Garden, Multi-Insect Killer Pyrethroid Caution Fipronil Over-N-Out Phenylpyrazole Caution Imidacloprid Bayer Advanced Lawn & Garden, Season-Long Grub Control Neonicotinoid Caution Lambda-cyhalothrin Triazicide Pyrethroid Caution Permethrin Spectracide Bug Stop Multi-Purpose Insect Control Pyrethroid Caution Steinernema scapterisci Mole Cricket Neamtodes (Gardens Alive) Biopesticide Caution Trichlorfon Bayer Advanced 24 Hour Grub Control Organophosphate Caution Hi-Yield Dylox 6.2 Granular