Metallic or Flatheaded Wood-Boring Beetles or Jewel Beetles
Additional images: dorsal view head and pronotum (click here), face view (click here), ventral view (click here).
Identification:
Adults are 3mm- 100mm long, but typically less than 20mm. The bodies are brilliantly metallic and are bronze, green, blue or black, particularly on the ventral side of the body and on the dorsal abdominal surface. Form compact, elongate, wedge-shaped and characteristic of family. They are hard bodied and inflexible. They are numbered at roughly 720 North American species and approximately 15,000 species total (Bland, 1978). This family resembles Click Beetles with similar tarsal segmentation, hard, sclerotized bodies and antennal serration. They differ from the Click Beetles in the pronotal shape, abdominal region and coloration (Ross, 1965). Also similar, yet unrelated, are the Longhorn beetles.
Antennae are filiform and serrate, and are not clubbed. Palps are long and flexible. The prothorax is without notopleural sutures.
The abdomen is nearly or completely covered by the elytra. Abdomen with 5 or 6 visible sterna, the first 2 are partly fused, and the suture between them is feeble. This suture is much less visible than the other abdominal sutures.
Tarsal formula is 5-5-5. The first visible sternum is not divided by the hind coxae, which are not very expanded, the hind trochanters without enlarged lobes (Borror, et al. 1989).
Many species can require more than 10 years to develop to maturity. There are records of some beetle larvae which were 40- 50 years old (Lanham, 1964). The Larvae are legless and elongate, with an expanded, flattened thorax. There are a few genera of small leaf-mining buprestids with minute legs (Ross, 1965).
Natural History:
This family is phytophagous and anthophilous, the diet consisting typically of vegetation and flowers in the adult stage and wood in the larval stage.
Habitat often will include dead or dying trees, logs and debris. They are also found on tree foliage, flowers and shrubs. This family seems to favor a wide variety of trees, including both deciduous and coniferous trees. Many of the larger beetles in this family can be found in sunny locations. The coloring acts as excellent camauflage for foliage and bark. Some buprestids who lay their eggs in freshly burned timber are attracted to smoke. Members of this family have been recorded to gather at smoke stacks of factories, and there is one account of these insects being seen coming upwind to a fire built for a monster pep rally at a Western University (Lanham, 1964). Most lay their eggs in crevices of the bark.
Defense behavior consists of typically flying, however some species will withdraw their bodies beneath them and fall to the ground at a sign of danger (Borror, et al. 1989). The buprestids can produce the chemical buprestin, a toxin used in deterring predators (Gullan and Cranston, 1994).
Buprestid adults are very active. They are rapid-running and flying insects and therefore can be elusive. Their activity is often the result of searching for mates or egg-laying sites. A few species produce twig galls (Bland, 1978).
The larvae create winding, grass filled tunnels beneath the bark surface, also creating oval holes. Some larval species of Brachys are leaf miners (Borror, et al. 1989).
Many Buprestidae are considered serious pests in orchards and to shrubs and forest trees. Some of these pest species include:
Agrilus champlaini: this species makes galls in ironwood (Borror, et al. 1989).
Agrilus ruficollis: this species makes galls in raspberry and blackberry (Borror, et al. 1989).
Chrysobothris femorata: Flat-headed apple tree borer. This species is a serious pest to orchards (Ross, 1965). The adult is about 12mm, attacking apple, peach, oak and other trees.
Members of this family have also been used as biological control agents, introduced to control certain plant populations. An example of this was between 1944 and 1948 in California when a few buprestids and chrysomelids were used to control Klamath weed reducing it to 1% of its original abundance (Borror, et al. 1989).
Some buprestids are used in jewelry making due to their beauty and brilliancy.
Literature Cited:
Bland, R. G. 1978. How to Know the Insects, 3rd Edition. Dubuque, Iowa, Wm. C. Brown Company Publishers.
Borror, D. J., Triplehorn, C. A., and Johnson, N. F. 1989. An Introduction to the Study of Insects, 6th Edition. New York, Saunders College Publishing.
Gullan, P. J. and Cranston, P. S. 1994. The Insects: An Outline of Entomology. London, Chapman & Hall.
Lanham, U. N. 1964. The Insects. New York, Columbia University Press.
Ross, H. H. 1965. A Textbook of Entomology. New York, J. Wiley.
