Martin,

The mole Cricket is one of the rarest invertebrates in the UK and is a Red Data species, fully protected by Law under the Wildlife & Countryside Act - which prohibits interference with places used for shelter or protection, or intentionally disturbing the animals whilst occupying such places.

It has hardly ever been seen by anyone for decades, and even then generally only as an individual insect in wetland regions of Surrey, Beds, Essex, Hampshire, Dorset & Oxfordshire.

Asking how to get rid of them is a bit like saying: "how do I get rid of these pesky Ospreys & Golden Eagles that might catch my goldfish"....except of course the Mole Cricket is far more rarely seen....

On the face of things it would seem somewhat unlikely that your wife's allotment has been chosen as the site of the resurrection of this ultra-fragile and quite spectacular 4-inch-long species, and perhaps she has another kind of insect amongst her veg instead?

If she has indeed sited any Mole Crickets then of course she should not disturb it in any way and contact English Nature's Mole Cricket Working Group with details of her sighting.