Mole crickets are relatively common, but because they are
nocturnal and spend nearly all their lives under ground in extensive tunnel systems, they are rarely seen. They inhabit agricultural fields and grassy areas. They are present in every continent except Antarctica; by 2014, 107 species had been described and more species are likely to be discovered, especially in Asia.
Neoscapteriscus didactylus is a pest species, originating in South America; it has spread to the West Indies and New South Wales in Australia.
Gryllotalpa africana is a major pest in South Africa; other
Gryllotalpa species are widely distributed in Europe, Asia, and Australia. They are native to Britain (as to Western Europe), but the former population of
G. gryllotalpa may now be extinct in mainland Britain, surviving in the
Channel Islands.
Invasive mole crickets and their biological control Invasive species are those that cause harm in their newly occupied area, where
biological control may be attempted. The first-detected invasive mole cricket species was
Neoscapteriscus didactylus, a South American species reported as a pest in St. Vincent, West Indies, as early as 1837; by 1900, it was a major agricultural pest in Puerto Rico. It had probably slowly expanded its range northwards, island by island, from South America. In 2001,
N. didactylus in Puerto Rico seemed to be a pest only in irrigated crops and turf. Small-scale experimental applications of the nematode
Steinernema scapterisci were made in irrigated turf, but survival of the nematode was poor. Very much later, this same species was reported as a pest in Queensland, Australia, presumably arriving by ship or plane. The next-detected invasive species was in the late 19th century in Hawaii, probably by ship. It was named as
Gryllotalpa africana, but much later as perhaps
G. orientalis. It was not identified as
Gryllotalpa krishnani until 2020. It attacked sugarcane and was targeted with
Larra polita from the Philippines in 1925, apparently successfully. The next detection was in Georgia, USA, and at that time was assumed to be
N. didactylus from the West Indies.
Scapteriscus mole cricket populations had built up since the early decades of the 20th century and damaged pastures, lawns, playing fields, and vegetable crops. From the late 1940s,
chlordane had been the insecticide of choice to control them, but when chlordane was banned by the U.S. EPA in the 1970s, ranchers were left with no economic and effective control method. Especially to aid Florida ranchers, a project that became known as the UF/IFAS Mole Cricket Research Program was initiated in 1978. In 1985, a multiple-authored report was published on accomplishments. In 1988, an account was published on prospects for biological control, and in 1996 an account of promising results with biological control. The program ended in 2004 after 25 years of running monitoring stations, and in 2006 a summary publication announced success: a 95% reduction in mole cricket numbers in northern Florida, with biological control agents spreading potentially to all parts of Florida. Efforts to use
Larra bicolor as a biological control agent in Florida began by importing a stock from Puerto Rico. It became established in a small area of southeastern Florida, but had little effect on
Neoscapteriscus populations. A stock from Bolivia became established in northern Florida and spread widely (with some help) to most of the rest of the state and neighboring states. Its survival depends upon the availability of suitable nectar sources. Once gravid female
Ormia depleta flies were found to be attracted to the song of
Neoscapteriscus males in South America, a path to trap these flies with synthetic mole cricket songs was opened. Experimentation then led to a rearing method. Laborious rearing of over 10,000 flies on mole cricket hosts allowed releases of living fly pupae at many sites in Florida from the far northwest to the far south, mainly on golf courses, and mainly in 1989–1991. Populations were established, began to spread, and were monitored by use of synthetic mole cricket song. Eventually, the flies were found to have a continuous population from about 29°N then south to Miami, but the flies failed to survive the winter north of about 29°N. Shipment and release of the flies to states north of Florida was thus a wasted effort. As the flies had been imported from 23°S in Brazil and could not overwinter north of 29°N, whether flies from 30°S in Brazil might survive better in northern Florida was investigated in 1999, but they did not. The third biological control agent to target
Neoscapteriscus in Florida was the South American nematode
Steinernema scapterisci. and on golf courses, which succeeded in establishing populations in several counties, and these populations spread, but sales were disappointing, and the product was withdrawn from the market in 2014. Although experimental application was made in states north of Florida, only in southern Georgia was establishment of the nematode verified, suggesting little interest in the other states.
As pests al wasp
Larra bicolor was introduced to Florida to help
control Neoscapteriscus mole crickets there. The main damage done by mole crickets is as a result of their burrowing activities. As they tunnel through the top few centimetres of soil, they push the ground up in little ridges, increasing evaporation of surface moisture, disturbing germinating seeds, and damaging the delicate young roots of seedlings. This is not the case when they have been accidentally introduced to other parts of the world. In Florida from the 1940s through the 1980s, they were considered
pests and were described as "a serious problem". Their population densities have since declined greatly. A University of Florida entomology report suggests that South American
Neoscapteriscus mole crickets may have entered the United States at
Brunswick, Georgia, in
ship's ballast from southern South America around 1899, but were at that time mistakenly believed to be from the West Indies. Another remedy that has been successfully applied is use of the parasitic nematode
Steinernema scapterisci. When this is applied in strips across grassland, it spreads throughout the pasture (and potentially beyond) within a few months and not only controls the mole crickets, but also remains infective in the soil for future years. ==In human culture==