Gryllotalpa gryllotalpa (L.)
(grill-oh-TALP-a grill-oh-TALP-a)
Distribution
The European mole cricket arrived in the United States in nursery stock from Holland and Belgium about 1913. It has now been reported from Massachusetts, New Jersey, New York, and Pennsylvania.
Description
As with other mole crickets in the genus Gryllotalpa, the tibia of the European mole cricket has four dactyls. There is a row of five spines on the upper margin of the tibia of each hind leg. This characteristic is shared by the western and oriental mole crickets, but not by the prairie mole cricket.
In the European mole cricket the ocelli are nearly circular, and the ocellar–ocular distance is greater than the ocellar length. In the western and oriental mole crickets, the ocelli are elliptical, and the ocellar–ocular distance is less than the ocellar length.
Life Cycle
The life cycle and seasonality of the European mole cricket seem not to have been studied in the northeastern United States. The following information is from studies in Europe, which may not reflect the situation in the United States. Oviposition begins in late April or May and continues for several months. The number of eggs per clutch usually is 100 to 300. The entrance to the egg chamber is left open, and the mother goes in and out of it, guarding the eggs from fungal growth by licking them. The nymphs remain in the egg chamber for a few weeks, feeding on plant rootlets and humus. When they first leave the egg chamber they remain under the protection of their mother. They develop slowly, and pass the winter as nymphs. Some of them, those which hatch early in the year, become adults late in the next year. Others, those which hatch late in the year, pass a second winter as nymphs. Therefore, the total development time is 18 months or even longer. Adults fly on very warm summer evenings.
This species is seldom, if ever, a pest in the United States. The situation is complicated because reports from various parts of Europe have ascribed differing behaviors to mole crickets under the name G. gryllotalpa. This suggests that, in reality, there are several species of extremely similar appearance but different behavior in Europe, only one of which is G. gryllotalpa. It is assumed here, that the species occurring in the northeastern United States, and believed to be an immigrant from Belgium, is the real G. gryllotalpa.
Life cycles of this and other species are contrasted in this tutorial with that of the tawny mole cricket, because it is the best-studied species.
Damage
This mole cricket is at most a minor pest in the United States, and is now rare in some western European countries.