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How to identify it
- The wasp is black with an entirely red abdomen, silvery white markings on the head, and smoky brown to indigo blue wings.[1][3]
- Females reach about 22 mm (just under an inch) long; males are smaller.[1][5]
- Away from flowers it is seldom seen. A hunting female runs over the ground in the brightest part of the day, stops, runs again, and slips into mole cricket tunnels.[1]
- On golf courses it has been found flying over, or resting on, turf with fresh mole cricket damage.[2][3]
Look-alikes
| Look-alike | How to tell them apart |
|---|---|
| Larra analis (native Larra wasp) | The native species has a black abdomen that is red only in part, typically at the tip. It attacks only the native northern mole cricket and lays its egg behind a hind leg of the host rather than between the first and second pairs of legs.[3][1] |
Where it lives
In Florida it descends from two releases: wasps from Brazil, by way of Puerto Rico, that settled around Fort Lauderdale from 1981 importations, and Bolivian wasps released near Gainesville in 1988 and 1989 and found established in 1993. It has since spread through Florida and has been recorded in southern Georgia, coastal Mississippi, southern Alabama and South Carolina, and in 2009 and 2010 at a golf course in Laurinburg, North Carolina.[1][2][3]
Biology and life cycle
Its hosts are the pest Scapteriscus mole crickets, which also come from South America; all three Scapteriscus species in Florida are attacked.[1]
A female enters a mole cricket's tunnel, chases the cricket out, pounces on it and stings its soft underside, paralyzing it for a few minutes. She lays one egg on the underside, between the first and second pairs of legs, sometimes after drinking a little of the cricket's body fluid. The cricket then recovers and burrows back into the ground.[1][2]
Mole cricket nymphs less than about a third to half grown are not attacked; beyond that, the wasps show no preference for host size.[1]
The larva feeds on the outside of the cricket with its jaws inserted, passes through five instars and kills its host. It pupates in the soil among the cricket's remains, inside a cocoon of cemented sand grains.[1][2]
Development from egg to adult takes about 50 days, longer when the pupa goes into winter diapause. There are several generations a year, and in northern Florida adults are present continuously through autumn until winter stops their activity above ground.[2][5][1]
In the southern United States adults have been seen from May to December, most abundantly from September to November, usually feeding at flowers.[1][5]
Adults need nectar from shallow flowers. Spermacoce verticillata (shrubby false buttonweed) is a favorite; other recorded nectar plants include partridge pea, cowpea, goldenrod, boneset, anise and fiddler's spurge, and in a northern Florida comparison four other nectar plants all drew fewer visits than Spermacoce.[4][1]
Damage and signs
Health risk
UF describes Larra wasps as solitary wasps that have no communal nest to guard and are not aggressive. Females use their sting to paralyze mole crickets.[1]
Control
Prevention
Leave it alone: UF/IFAS deliberately introduced this wasp as a biological control agent for pest mole crickets and has worked to spread it through Florida.[1][5]
Biological control
To attract and hold the wasps where mole crickets are a problem, provide nectar plants, especially Spermacoce verticillata; the wasps forage for mole crickets more effectively when it is available. The plant is not native to Florida, grows vigorously in full sun and has been reported as a minor weed in southern Florida.[4][5]
How it came to the United States
Pest Scapteriscus mole crickets reached the southeastern United States around 1900, probably as stowaways in ships' ballast, and became important pests of crops, turf and pasture grasses. The native Larra analis never adapted to attack them.[1]
Larra bicolor was established in Puerto Rico from Brazil in the late 1930s. Attempts to bring it to Florida in the 1940s failed and were dropped once chlordane came into use; after chlordane was banned, the Florida Legislature ordered a UF/IFAS mole cricket research program in 1978, and the effort resumed.[1][5]
Wasps from Puerto Rico released at five Florida sites survived only at Fort Lauderdale, where they parasitized under 1 percent of one mole cricket species and none of the other two. Wasps from Bolivia, chosen in the hope that stock from a cooler climate would survive Florida winters better, were released near Gainesville and proved highly effective against pest mole crickets at two study sites.[1]
Since the wasp and an introduced mole cricket nematode, Steinernema scapterisci, were established in the 1980s, pest mole cricket populations in north central Florida have declined by 95 percent.[5]
Native mole crickets are not at risk
UF reports that about 90 percent of the wasp's attempts on the native northern mole cricket fail because the cricket entangles the wasp in a sticky secretion, and that eggs laid on it die or the larvae that hatch die. Native mole crickets do not seem to be at risk.[1]
Common questions
- Is this wasp dangerous to people?
- UF describes Larra wasps as solitary and not aggressive; they have no communal nest to guard.[1]
- How can I attract mole cricket hunters?
- Plant nectar flowers near mole cricket problems. Arevalo and Frank call Spermacoce verticillata the best way to attract the wasp, and plots of it are used to spread the wasp in Florida, though the plant is not native there and has been reported as a minor weed.[4][5]
- Do mole cricket insecticides affect the wasp?
- Researchers in North Carolina note that widespread insecticide treatment in recent years has significantly reduced both the mole cricket hosts and the sites available to Larra bicolor.[2]
Sources
- University of Florida IFAS Extension (Featured Creatures), “Larra Wasps, Larra analis Fabricius; Mole Cricket Hunters, Larra bicolor Fabricius, EENY-268 (J. H. Frank and A. Sourakov, 2002; archival copy).” journals.flvc.org/edis/article/view/108220 (accessed 2026-11-09)
- Florida Entomological Society (Florida Entomologist), “First Record of Larra bicolor (Hymenoptera: Crabronidae) in North Carolina (P. T. Hertl and R. L. Brandenburg), Florida Entomologist 96(3), 2013.” journals.flvc.org/flaent/article/view/82622 (accessed 2026-11-09)
- Florida Entomological Society (Florida Entomologist), “Occurrence of Larra bicolor (Hymenoptera: Sphecidae), Ectoparasite of Mole Crickets (Scapteriscus spp.), in Coastal Mississippi (D. W. Held), Florida Entomologist 88(3), 2005.” journals.flvc.org/flaent/article/view/75447 (accessed 2026-11-09)
- Florida Entomological Society (Florida Entomologist), “Nectar Sources for Larra bicolor (Hymenoptera: Sphecidae), a Parasitoid of Scapteriscus Mole Crickets, in Northern Florida (H. A. Arevalo and J. H. Frank), Florida Entomologist 88(2), 2005.” journals.flvc.org/flaent/article/view/75410 (accessed 2026-11-09)
- Florida Entomological Society (Florida Entomologist), “Management of Pest Mole Crickets in Florida and Puerto Rico with a Nematode and Parasitic Wasp (N. C. Leppla, J. H. Frank, M. B. Adjei and N. E. Vicente), Florida Entomologist 90(1), 2007.” journals.flvc.org/flaent/article/view/75637 (accessed 2026-11-09)
- iNaturalist, “Larra bicolor taxon page (order and family).” www.inaturalist.org/taxa/451964 (accessed 2026-11-09)