Ground Beetles: The nocturnal insecticides

Ground beetles too do the work of insecticides during dark hours. Though I had often seen them in my childhood in the backyard of our house and in our fields during daytime after rains. These beetles live in the soil and generally seen on the ground but they devour insects on plants during night. Ground beetles as a group is the largest groups of beetles.Although members of the group differ slightly in their body shape and color, but most are shiny and black(some are metallic), and have ridged wing covers. Body size varies from 7 mm to 13 mm. Forewings are hard elytra with linings. Another phenotypic trait common to ground beetles is a smaller head than thorax, and threadlike antennae.  Ground beetles have well developed sickle shaped serrated mandibles. They use their biting type mouth parts to devour other insects. Trochanta is absent, so it can run very fast.

Adults are active at night and tend to hide under rocks during the day time. They will run when exposed. They come out at night to feed on other insects. Likely targets include caterpillars, root maggots, snails and other soft bodied insects. Most species don’t use their wings, but a few may fly to lights at night.

Ground beetles undergo complete metamorphosis. Female ground beetles lay their eggs in the soil. Eggs hatch into larva that feed upon insects in or on the soil under debris. Depending on the species, there may be several generation per year. Sometimes they invade the house if food become scarce or moisture condition are unfavorable. Ground beetles larvae like adults, are important predators. The larvae live below the ground, where they use their large pincher like mandibles to devour soil-dwelling insects. Both adults and larvae act as insecticides as they feed on larvae of other insects including pests.

Adults may wander into homes by crawling through small openings or under doors. They will not stay inside, they prefer the outdoors. Since the ground beetles are beneficial insects, control is not warranted. However if they are creating a nuisance, move or remove hiding places next to the houses such as log piles, mulch and debris. Beetles found indoors may be swept up and discarded.
                      If beetles are creating nuisance by flying to lights at night, repositioning the lighting or changing white light to yellow may reduce attraction.

Thus these beetles can help me in diminishing the poison residues in vegetables, fruits and grains consumed by me. No doubt if permmitted they can also help farmers in reducing their expenditure on insecticides.