Pest Mole Crickets Biology Management Eileen A Buss

Pest Mole Crickets: Biology & Management Eileen A. Buss, Entomology & Nematology Department, UF/IFAS What’s the problem? Mole crickets tunnel in the soil and feed on plant roots, especially grasses. Are there natural controls? Researchers found several natural enemies in South America, where the pest mole crickets originated, and released them in the U. S. to naturally suppress mole cricket populations. • Damage in pastures (Fig. 1) reduces forage production and contributes to bahiagrass decline. 1 3 2 4 • Root and stem injury on vegetable plants (Fig. 2) reduces plant growth and crop yields. • Mole crickets reduce the aesthetics and playability of grass on golf courses and athletic fields (Fig. 3). • A parasitic wasp, Larra bicolor, feeds on nectar (Fig. 13) and then lays an egg on an adult mole cricket. The larva hatches and feeds externally on the adult’s body (Fig. 14). 13 14 • The Brazilian red-eyed fly, Ormia depleta, listens to adult mole cricket songs, and lays live larvae on adult mole crickets that it finds (Fig. 15). The larvae feed internally, then exit the body and pupate in the soil (Fig. 16). • Sod farms cannot lift quality grass that has a weak root system caused by tunneling damage (Fig. 4). 15 16 Why are they bothering me? 5 6 Which species are pests? 7 10 8 11 9 12 Adult mole crickets are attracted to lights left on at night (Fig. 5) and moist soil (Fig. 6). They disperse by flying in the spring and fall, and by tunneling large distances at night. They feed on nearly all grass species, but prefer bahiagrass and bermudagrass. • The larvae of a predatory beetle, Pheropsophus aequinoctialis, feed on mole cricket eggs, but the adults are general scavengers (Figs. 17, 18). However, this beetle is still in quarantine and has not been released outside. • Insect-parasitic nematodes (Fig. 19) can be purchased and applied on infested land. Applications should be done when adults are present, from February to March, or September to October. They enter a mole cricket through the spiracles (breathing tubes) or mouth, release bacteria that kill the pest, feed on the bacteria, and reproduce inside the mole cricket (Fig. 20). Applications should be made late in the day, with lots of water. These nematodes do not damage plants. 17 18 The three pest species arrived in the early 1900 s by hitchhiking on ballast in ships. They now occur throughout the southeastern U. S. The three pest mole crickets species (tawny, southern, and shortwinged mole crickets) can be identified three ways: wing length, pronotum pattern, and dactyl spacing. • Wing length. As adults, tawny and southern mole cricket wings are as long as their bodies. The wings on shortwinged mole crickets are less than half as long as their body. 19 20 When should I apply insecticides? The best time to control mole crickets with insecticides is just after egg hatch in late spring or early summer, when the nymphs are young. The best way to time an application is to do a “soap flush” (Fig. 21). Mix 1 -2 TBSP of lemon liquid dish soap in a gallon of water and pour it over the damaged area. Wait 1 -3 minutes, and the mole crickets will come to the surface. By using a soap flush, you can determine the size and species of mole crickets. • Pronotum pattern. A distinctive color pattern is just behind the head. See Fig. 7 for the tawny mole cricket, Fig. 8 for the southern mole cricket, and Fig. 9 for the shortwinged mole cricket patterns. • Dactyls are the “tooth-like” claws on the front legs, and the space between them is important. Tawny mole crickets have a “V-shaped” dactyl space (Fig. 10), and southerns and shortwings have “Ushaped” dactyl spaces (Figs. 11, 12). 21 If you collect an adult female mole cricket in the spring, cut open her abdomen and feel her eggs. If they are soft, then she hasn’t started laying eggs. If they are hard like a BB, then she is ready to lay eggs. Peak egg hatch will be several weeks later. Many insecticides are available to control mole crickets. Consult your local Cooperative Extension office, or visit http: //edis. . ifas. ufl. edu for specific recommendations.