Wednesday, October 25, 2017

Virginia Metallic Tiger Beetle

The Virginia Metallic Tiger Beetle (Tetracha virginica), also goes by the name of Big-headed Tiger Beetle and when you look at these pictures it is easy to see how it earned a name like "big-headed." Their face seems to meld into their thorax with very little definition between the two, this gives the illusion that their face and thorax are all one very large head. They are the largest tiger beetle in this genus, and are found throughout much of  the Eastern United States. While they are considered common they are rarely seen, most likely due to the fact they're almost strictly nocturnal. They are attracted to lights at night and spend the night time hours hunting for insect prey to feed on. During the day they hide out under debris of some kind, usually wood piles or rock piles. They are also known to occasionally congregate in large numbers in cracks or crevices of walls or in dry ground during the day.

You are most likely to encounter them in late summer or early fall, but it is not entirely uncommon to see them anytime between late spring and late fall before the first freeze.

No other tiger beetle looks quite like them, not only are they very large for a tiger beetle, they are a dark metallic green from the tip of their head to the tip of their abdomen. The legs, antennae, and mandibles are tan. Eyes are bulbous and dark.

Like all tiger beetles they are incredibly fast and difficult to get a good look at. Most tiger beetles can fly, but like all tiger beetles in the genus Tetracha they are flightless, or very poor flyers. They seem to rely on their rapid running abilities. They are often found near rivers and lakes. They also occur in suburban areas in lawns, open grassy areas and bare ground. I found the one pictured here alongside the Missouri River in St. Joseph. It was scurrying along the sidewalk right outside where I work.

 As both grubs and adults they feed on various insects. Many tiger beetles in this genus seem able to "hear" or sense the underground activity of insects living in the soil. This ability helps them locate potential prey. Their feeding habits can help biologically control things like June Beetles or Mole Crickets (that may be feeding on your turf) while they are still in the grub stage.

We should consider these beetles beneficial and encourage their presence, even if those large mandibles make them look menacing. They are harmless unless you grab one, then you might earn yourself a nip from those oversized chompers, but leave the beetle alone and it will surely leave you alone.

1 comment:

  1. I haven't seen much under my light at night, the season has slowed

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