The delta green ground beetle is currently known to live only in the Jepson Prairie region of Solano County. Rarely seen, adults are metallic green and bronze, and live near the edges of the prairie’s large vernal pools, which are called playa pools. The population size is unknown and locating individuals remains a challenge due to how little is understood about the beetle’s life cycle.
The delta green ground beetle was listed as threatened on August 8, 1980 and is threatened by:
- Small population size, in a limited range
- Agricultural use of lands
- Climate change that results in drying of vernal pools
- Non-native and invasive plant species that don’t provide the right cover
Based on observations of beetles in the field, researchers believe that delta green ground beetles are predators that feed on many different kinds of prey. The most important food source is believed to be springtails. The delta green ground beetle has also been observed eating larvae and adult midges, as well as beetle larvae of other undetermined species.
The delta green ground beetle is approximately 0.25 inches (0.6 centimeters) long.
The delta green ground beetle is typically brilliant metallic green and bronze. There are two slightly different color forms. Most adults are metallic green with bronze spots on the elytra, which is the first pair of wings, but some adults lack the spots and are nearly uniform metallic green. Larvae of the delta green ground beetle are seldom seen.
There is only one generation per year, but some early adults appear quite worn, which suggests that they may live at least one year and possibly even longer.
Adult females are thought to lay eggs once per year.
Much about the delta green ground beetle’s life cycle remains unknown. Experts hypothesize that adults undergo a period of dormancy until the first warm days of late winter, when they emerge from underground homes and females lay their eggs. When the pools dry and the weather turns hot, the beetles go dormant again. Beetle larvae crawl into cracks in the soil to survive the hot, dry summer and fall as dormant pupae.
The delta green ground beetle is found along the edges of vernal and playa pools, which are formed primarily on clay soil. Adults hide in cracks in the soil and beneath low vegetation during the wet season. They can be seen sunning on bare prairie during their active months. During the dry seasons of summer and fall, experts hypothesize that the beetle larvae survive the heat by resting dormant in cracks in the soil.
Land on which the natural dominant plant forms are grasses and forbs.
Environments influenced by humans in a less substantial way than cities. This can include agriculture, silvaculture, aquaculture, etc.
Areas such as marshes or swamps that are covered often intermittently with shallow water or have soil saturated with moisture.
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