The Wasp That Kills Mole Crickets

July 2006
Gary Mikulcky - Highlands County Extension, Directory & Livestock Agent

Larra Wasp

A South American wasp, Larra bicolor Fabricius, has proven to be a predator of the mole cricket in Florida. This wasp is a member of the family Sphecidae (digger wasps). In 1988-89 UF/IFAS researchers released Bolivian stock of L. bicolor wasps in Alachua County. They became established and have spread to neighboring counties and continue to spread.

Adult female L. bicolor seeks out mole crickets in their burrows and chases them outside. It then stings the mole cricket to temporarily paralyze it. L. bicolor then lays an egg on the underside of the mole cricket; the mole cricket recovers and goes about its business. The L. bicolor hatches into a larva and feeds on the mole cricket from the outside and eventually kills the mole cricket.

The larva consumes the mole cricket in about two weeks. It then moves into the soil and develops a cocoon and turns in a pupa. L. bicolor then pupates and emerges as an adult wasp and digs its way to the soil surface. This will take a minimum of six weeks.

When the L. bicolor emerges from the soil it is looking food. That food source is nectar from a flower. This nectar source is vital to nourishment of the wasp and for egg production. The wasp prefers the nectar of the wildflower Spermacoce verticillata (southern Larraflower, shrubby false buttonweed, whitehead broom,). Planting the Larraflower will help L. bicolor to become establish and aid it to survive in areas where mole crickets occur.

The L. bicolor wasp is not nearly as aggressive as the paper wasps that live on the eaves of my house. I have put my arm in a cage with L. bicolor and tried to aggravate them by picking them up and have not been stung. They will sting but I am told it is very mild.

Southern Larraflower

L. bicolor is another method of biological control of the mole cricket. To be an effective control agent the wasp needs to be persistent year after year. Planting Southern Larraflower will help establish a permanent population of L. bicolor. I have included pictures of the Southern Larraflower, but have not been visited by L. bicolor in order to take a picture.

potted Larraflowers may be propagated by seed and cuttings
Potted Larraflowers may be propagated by seed and cuttings.

the Larraflower stem grows up through the center of the flower
Note how the Larraflower stem grows up through the center of the flower.

To obtain seeds of the Larraflower contact:

  • Martin B. Adjei
    Associate Professor/Forage Extension Specialist
    3401 Experiment Station
    Ona, FL  33865

    (863) 735-1314 x209

References

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