The function of turret building behaviour in the larval tiger beetle, Cicindela willistoni (Coleoptera: Cicindelidae)

Abstract

1. Cicindela willistoni LeConte (Coleoptera: Cicindelidae) adults and larvae occur only on saline and alkali flats with little or no vegetation in southwestern U.S.A. Unlike other larval tiger beetle species, C.willistoni constructs a chimney‐like extension (turret) 1–4 cm above its burrow.2. The function of these unique turrets was tested in relation to several biotic and abiotic factors in the Sulphur Springs Valley, Arizona, U.S.A.3. The turrets did not prevent flooding of the larval burrows.4. They did not prevent or reduce the frequency of parasitoids (mainly bombyliid flies of the genus Anthrax).5. The turrets did not make it possible for the adult and larval beetles to feed on obviously different types or sizes of prey.6. However, larvae with turrets were raised sufficiently above the substrate surface and boundary layer to allow them to thermoregulate in the lower temperatures at these heights and remain active throughout the day.7. The shade produced by the turrets attracted significantly more potential prey items than were available to turretless larvae in the same habitat.