LARRA BICOLOR
(HYMENOPTERA: SPHECIDAE), A
BIOLOGICAL CONTROL AGENT OF
SCAPTERISCUS
MOLE
CRICKETS (ORTHOPTERA: GRYLLOTALPIDAE),
ESTABLISHED IN NORTHERN FLORIDA
Larra
is a largely tropical genus of digger wasps (Sphecidae) with atypical behavior.
Typical sphecid females sting and paralyze other arthropods which then are taken
to cells where they serve as food for larvae.
Larra
females attack and sting mole crickets
(Gryllotalpidae), which suffer paralysis for only a few minutes. The
Larra
females
oviposit on the mole crickets that they have paralyzed, and the neonate larvae develop
as external parasitoids on active hosts (Bohart & Menke 1976). The only known hosts
of
Larra
are mole crickets.
Larra analis
F. is the only species native to coastal southeastern USA, and its host
is
Neocurtilla hexadactyla
(Perty), the only mole cricket native to this region. Three
immigrant species of mole crickets of the genus
Scapteriscus
arrived in the southeastern
USA about 1900. Tens of thousands of these
Scapteriscus
mole crickets have been
examined by personnel of the University of Florida’s mole cricket research program
since 1978, but none was found with an egg or larva of
L. analis
. This is strong evidence
that
L. analis
does not attack
Scapteriscus
spp. in nature.
Some mole cricket species are pests of agriculture and horticulture. Notable examples
are
Gryllotalpa orientalis
Burmeister in Hawaii,
Scapteriscus didactylus
(Latreille)
in Puerto Rico and some other West Indian Islands, and
Scapteriscus vicinus
Scudder,
S. abbreviatus
Scudder, and
S. borellii
Giglio-Tos in the southern USA