SOUTHERN MOLE CRICKET

Scapteriscus borellii Giglio-Tos
(scap-terr-ISK-us bor-ELL-ee-ee)



Distribution

The southern mole cricket arrived in Florida and Georgia about 1900, from southern South America, and spread north and west. It is currently located in Florida, Georgia, South Carolina, North Carolina, Alabama, Mississippi, Louisiana, Texas, Arizona, and California. Colder temperatures ultimately will limit the spread of the southern mole crickets to the north.

Description

The southern mole cricket is a slim, very active, mole cricket. Often, when captured, it will "play dead" but then suddenly begin moving rapidly.

Unlike other mole crickets, it has widely separated tibial dactyls. The color pattern of the dorsal side of the thorax is helpful in distinguishing between Scapteriscus species.


Left foreleg - innerside - of a southern mole cricket.

The wings are longer than the abdomen. Another key identifying characteristic is found on the thorax. However, the thorax has two color forms. In NC, SC, LA, TX and peninsular Florida, southern mole crickets usually have a dark thorax with four pale dots. In GA, AL, MS and northern Florida, this mole cricket commonly has a mottled thorax.


Four-dot thorax of a southern mole cricket.
Life Cycle

In Georgia and central and northern Florida, the life-cycle and seasonality are much the same as for the tawny mole cricket, except that activity begins a few weeks later in the year and ends a few weeks later. The southern mole cricket has a minor flight period in October-November. Females have not been induced to oviposit at times other than their normal April-May oviposition period. A greater percentage of individuals (than in the tawny mole cricket) overwinters as nymphs, to mature the following spring.

However, in southern Florida, this species perhaps has an additional generation, to give it two generations each year. Here, there is a flight season beginning in March and ending in May (with a peak in April), and then a second flight season beginning in June and ending in August (with a peak in July). Each flight season is believed to be accompanied by oviposition. The development time of nymphs from these breeding periods is not well-understood. It is not clear whether nymphs that develop from the first breeding period can develop extremely rapidly to become adults that can participate in the second breeding season.

The ranges of southern mole crickets and tawny mole crickets overlap, but there are several importance differences between them. A major difference is that southern mole crickets are mainly carnivores, feeding only to a slight extent on plant roots, stems, and leaves. Secondly, southern mole crickets are much more active than tawny mole crickets on the soil surface and underground; probably for this reason they are more susceptible to Steinernema scapterisci, a parasitic nematode. A third difference is that the flights of southern mole crickets begin and end slightly later in the evening. Lastly, the spring flights of southern mole crickets typically begin and end a few weeks later than those of tawny mole crickets.

Damage

The southern mole cricket damages turf and pasture grasses, mainly by tunnelling (because it is largely carnivorous). Dissection of their guts to reveal the contents has shown that southern mole crickets feed largely on a diet of insects and other soil-inhabiting animals, and only to a slight extent on plants. Perhaps plant feeding occurs when animal material is in short supply. Relatively very little damage is caused to plants by southern mole crickets as a consequence of this diet. Southern mole crickets include ants in their diet, and they may perhaps feed on fire ants among other ants.

Biological Controls

Steinernema scapterisci Nguyen & Smart is a species of steinernematid nematode native to South America. Living specimens were obtained in Uruguay in 1985 and brought to Gainesville for testing by members of the UF/IFAS mole cricket program. Initial tests showed that S. scapterisci killed all southern mole crickets exposed to it.



Steinernema scapterisci nematodes emerging from a mole cricket they have killed

The nematodes move about very little in soil. They are capable of slight movement toward and away from the soil surface. However, they basically must depend upon a potential host insect moving very close to them in the soil. They can be dispersed to new sites by host insects before those hosts become so sick due to the infection that they cannot move. For example, infected adult tawny and southern mole crickets can fly at least a mile, perhaps more, and when they die will release third-stage juvenile nematodes into the soil.

Ormia depleta (Wiedemann) is a species of tachinid fly native to South America. In the 1930s in Amazonian Brazil, its larvae were found to be parasitoids of Scapteriscus mole crickets. In the 1980s in Paraguay, adult female Ormia depleta were found to be attracted to songs of southern mole crickets when these songs were produced artificially by a sound-emitter developed by the UF/IFAS mole cricket program.



Larra bicolor F. is a species of crabronid wasp native to South America. Introduction of stock of it from Puerto Rico (originally from Amazonian Brazil) into Florida in 1979-1981 led to its establishment at Ft. Lauderdale. Introduction of stock of it from Bolivia into Florida in 1988-1989 led to its establishment at Gainesville.




An adult Larra bicolor stinging a mole cricket to paralyze it before laying an egg

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