By Kathy Feagan – Big Country Master Gardener
Long-necked Ground Beetle (Colliuris pennsylvannica;Linnaeus) are found all over the U.S., Mexico, West Indies and Canada. They prefer wet areas and are drawn to lights. They are extremely capable aphid predators. They are often found near water, gardens, yards, cultivated fields, vacant lots, along riverbeds and in soybean fields breeding and hunting aphids. To protect themselves from predators, they are able to emit sprays of acetic and fomic acids and also create sounds while rubbing their wings. They grow ¼” to 1/3” in length. They have an elongated neck, with a swelling in the center of the neck. Their pronotum is dark red to black, with yellowish margins around their beautifully patterned abdomen. Their long legs help them run fast. They find refuge in decaying wood, leaf litter and soils for protection and for foraging. Adults are active from spring to late fall, when most overwinter as larvae or adult stage. After mating in spring, the females lay eggs one at a time, in soil or leaf debris, and then leave them to fend for themselves. The young go through four stages: egg, larvae, pupa then adult. The larvae feed on invertebrates (worms, grubs, spiders, etc.) then pupate in the soil until they emerge as adults. These are considered beneficial insects as they control pests and improve soil health.
Gazella Scarab dung beetle, iNaturalist, Robert Webster
Caterpillar Hunter Beetle (Calosoma scrutator) are gorgeously metallic, large ground beetle predators. They are also called “Fiery Searchers”. They climb trees and traverse fields to pursue caterpillars, usually at night. They are considered beneficial in controlling pests. They are very fast, have strong jaws and can emit an unpleasant spray to discourage predators. They can grow to nearly 1 ½” long. Most of this species are black but some are bright blue, green or even violet metallic color. Some of these insects were imported in 1905 to control spongy moths. They are found in gardens and fields and spend their days under rocks, logs, garden debris or in crevices. They mainly hunt at night. They do have wings but rarely fly. Females lay a single egg into the soil. The eggs hatch within 2 weeks into larvae. The larvae are pale white with strong jaws. Over the next 4 to 9 weeks, they grow, become darker and mature rapidly, going through their second through the fourth and final instar when they begin pupation in the soil. Adults usually live about 2 years but some have been reported to live for up to 4 years. Adults and larvae feed on caterpillars, especially tent and Gypsy moth caterpillars. One larva can eat about 50 caterpillars while undergoing instars. They also feed on caterpillar larvae.
Black Caterpillar Hunter Beetle, Reese WB
Dung Beetles (Phangeus vindex ), “Rainbow Scarabs”, are found on every continent except Antarctica. There are over 9,500 species of dung “scarab beetles” worldwide and 58 species in Texas. Other common Texas species, are the solid dull black Texas Black Phanaeus (Phanaeus triangularis texensis),theiridescent blackBlue Phanaeus (Phanaeus Adonis), andan introduced species, Gazelle Scarabs (Onthophagus gazelle), a dull blackbeetle. This beetle was introduced to Texas by USDA scientists in the 1970’s. Dung beetles are said to remove up to 80% of cattle droppings throughout Texas. They grow from ¼” to 1” long and are metallic blue-green to copper. The copper front of the head is flat. Males have a long, curved horn while females have a nodule. They feed on dung (herbivore and carnivore dung), mushrooms, fruits and decaying leaves. Because dung gives them all the nutrients they require, they do not have to drink or eat anything else but, since they are carnivores, they also enjoy millipedes and ants.
Dung Beetles – rolling dung – Arno Meintjes CC BY NC-SA 2.0
Dung Beetles have three types to complete their feeding and nesting. There are roller, tunneler and dweller dung beetles.
- Rollers roll and bury dung balls. During mating a male and female beetle meet at the dung pile. The male begins rolling and the female helps roll, rides the ball or follows behind the rolling male. When they find a soft place in the soil, they bury the ball and then mate underground. After mating, they prepare a brooding ball into which the female lays her eggs. Usually, they remain to protect the eggs. Once the eggs hatch, the larvae feed on the dung ball using their strong jaws to chew up undigested materials. The larvae go through complete metamorphous and finally emerge as adults. Rollers are terrific dispensers of seeds, with the dung ball also being a great fertilizer.
- Tunnelers bury any dung they find into soil. They dig tunnels under the dung for laying their eggs.
- Dwellers live inside the dung. Each of the eggs they lay eventually eat about 40% of the dung ball and the rest becomes fertilizer. The tunnels loosen compacted soils and make paths for water to drain deeply into soils.
All dung beetles are able to find dung miles away with their profound sense of smell, utilized through their antennae. Some jump upon the dung producing animal to await dung. When the rollers get their dung, they roll it following an exceptionally straight line. Many scientists believe dung beetles use the night skies for navigation. Dung beetles are incredibly strong with the ability to pull 1,400 times their own weight. Some beetles are able to bury 250 times their own body weight each night.
Female Rainbow Scarab Dung Beetle – Thomas Shahan
Dung Beetles are extremely beneficial in several ways. First, they keep the ecosystem healthy by removing dung and all the nitrogen, which disperses ammonia, into the air. The beetles mix the nitrogen into the soil where it is absorbed by plant matter. Secondly, they reduce filth-breeding flies, parasite and pest populations by removing dung that pests and parasites need for moisture and breeding. Experts say the work of the dung beetles (decomposition and inserting nutrients into soil) saves farmers and ranches over $350 million each year.
Gazella Scarab dung beetle – iNaturalist – Robert Webster
Sadly, they are decreasing in population from loss of habitat and the application of dewormers used for livestock and pets. The dewormer’s ingredients pass through animals and are deposited into dung. When dung beetles are exposed, they have lower survival and reproduction rates. Unfortunately, parasites can become resistant to the chemicals and overpopulate. Firefly larvae and other insects that develop in soil are also exposed and the chemicals can even be absorbed by plants and released through pollen, nectar and dust, greatly hurting bees and other pollinators.
Stefan Allen – Insects Unlocked University of Texas
If you have any gardening questions, call the Taylor County Extension Office at 325-672-6048 or email us at mgardeners@yahoo.com. We hope you visit bcmgtx.org for all Big Country Master Gardener information and events, like us on BCMGA Facebook, and check out training presentations on BCMGA YouTube. We are here to help you.
Until next week, Happy Gardening!