Omus californicus- California Night-stalking Tiger Beetle


Circle of Life



    Omus californicus, commonly referred to as the California Night-stalking Tiger Beetle, is a nocturnal organism with four known classified subspecies (Pearson and Vogler 2001, Pearson et al. 2005). Once at adulthood, the California Night-stalking Tiger Beetle females can then reproduce and mate with males. To initiate copulation between a female and a male, the male approaches the female until close enough to lunge onto the female’s back (Shivashankar and Pearson 1994). Once on the back of the female, the male attaches to the female by a firm grasp on her thorax with his mandibles and front legs, while the hind legs remain on the ground to allow dual movement between the two tiger beetles (Shivashankar and Pearson 1994). During copulation, the male will grasp the female and ride atop her back during a period known as amplexus and may still continue to ride the female after this process for a short period (Shivashankar and Pearson 1994). Larvae of Omus Californicus

    Following copulation, the female searches for and creates a burrow location which mostly consists of clay sediment (Kinsley and Julian 1988, Pearson and Vogler 2001, Pearson et al. 2005). The female commonly examines the soil through the senses of touch and taste. By use of the antennas, the female will gently touch the soil, and might also grasp a few grains of soil to determine if the texture of the sediment will be the best available soil conditions for the egg (Brust et al. 2012, Kinsley and Julian 1988). California Redwood tree paths provide a safe location to the, often clumped, burrows (Pearson et al. 2005). Upon finding a suitable place to create a burrow, the female Omus californicus will begin to dig into the soil removing the sediment by use of the gonapophyses, which allows the Tiger Beetle to move the soil to the side and create a deeper burrow (Brust et al. 2012). Once complete, the burrow ranges between six and nine millimeters in length and between twenty-five to thirty centimeters in depth (Kinsley and Haines 2010). The female will then deposit a single egg which is two to four millimeters in length into the hole of the burrow and refills the opening with the disturbed sediment from the formation of the burrow to protect the egg (HanCalifornia Night-stalking Tiger Beetleson 1998, Burst et al. 2012).


Growth and Development

      Omus californicus typically lives 3 years and matures through three different instars, or growth phases, during the larval development: the first instar, the second instar, and the third instar which attributes to most of their life span (Pearson et al. 2005, Kinsley and Julian 1988). The egg typically hatches within two to four weeks, upon which the California Night-stalking Tiger Beetle enters the larval stage of development (Hanson 1998).  The maturation of the larvae depends on abiotic factors such as temperature (Burst et al. 2012), while the maturation time depends heavily on food availability; therefore the larval survival rate increases corresponding to an increase in food availability (Burst et al. 2012, Kinsley and Julian 1988). The first instar lasts a few weeks while the second instar of development occurs between one to a few months (Kinsley and Julian 1988). The final instar of maturation happens from six months to a year (Kinsley and Julian 1988). The larvae of Omus californicus is highly similar to other species and other genuses of Tiger Beetles (Pearson and Vogler 2001). The larvae have a white cream coloration covering the developing organism, with large hooks at the bottom mid-rear to help anchor themselves when catching prey; the large head is capped with a black plate and on the abdominal hump there are three paired spines (Pearson and Vogler 2001, Hansan 1998). The carnivorous larvae then gather food by burrowing a unique tunnel to the surface of the soil to attack prey by quickly grasping passing organisms and dragging the organism back into the burrow (Pearson and Vogler 2001, Burst et al. 2012, Kinsley and Juliann 1988). Once reaching adulthood, Omus californicus is highly agile and quick, active primarily from May to June. (Spomer et al. 2008, Pearson et al. 2005).




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