This tool is part of the Citrus Resource

Citrus Pests

 

Beetles

 

Scientific name

 

Order Coleoptera

Similar species

 

Beetles can be easily mistaken for cockroaches or true bugs. Each group can be easily distinguished by antennae type, mouthparts, and wing position at rest.

Beetles Cockroaches True bugs
Antennae Segmented antennae Long, filamentous Varies
Mouthparts Chewing Chewing Piercing-sucking
Wing position at rest Elytra fold flat to create a straight line down the middle of the back Wings directly overlap on the back. Wings gently overlap on the back or may appear roof-like

Diagnostic characteristics

 
Adults
  • Smallest size - 5.5 mm (0.22 in.)
  • Largest size - 35mm (1.38 in.)
  • Entire body strongly hardened (sclerotized).
  • Oval and either large and elongate or short and stout.
  • Either monochrome or varicolored body with assorted spot or stripe patterns.
  • Chewing mouthparts that include well-developed mandibles.
  • Elbowed (geniculate) to thread-like (filiform) antennae.
  • Antennae either uniformly hued or patterned with alternating colored bands.
  • Large compound eyes with no ocelli (simple eyes).
  • One hardened pair of forewings (elytra) and one pair of membranous hindwings.
  • Elytra are posteriorly tapered and either smooth, scaled, or indented.
  • Membranous hindwings folded beneath the elytra when at rest.
  • Closed elytra form a straight line down the middle of the back. Some species have fused elytra and therefore cannot fly.
  • Weevils have downward sloping beaks (snouts). Species with well-developed snouts have laterally situated elbowed antennae, a prolonged head, and reduced mouthparts at the snout tip.
  • Weevils with short, poorly-developed snouts have a more rounded head.
  • Beetles have unique 'foot' or tarsal formulas since the number of tarsomeres or foot segments in the front, middle, and hind leg vary. Leaf beetles and weevils with a 5-5-5 tarsal formula while long-horned beetles have a 4-4-4 tarsal formula.
Pupae
  • Smallest size - 5.8 mm (0.23 in.)
  • Largest size - 38 mm (1.5 in.)
  • Oval in shape.
  • Appendages are free and detached from the pupal case.
  • Off-white to yellow color which darkens prior to adult emergence.
  • Lacking mandibles.
  • Protective covering structurally similar to adults but with wing pads.
Larvae
  • Smallest size - 8.5 mm (0.33 in.)
  • Largest size - 52 mm (2.0 in.).
  • Between 4 - 11 larval instars.
  • Larvae are usually grub-like and legless with distinct body segmentation. Some species have a kidney-bean shape.
  • Yellow to milky-white body color which darkens before pupation. Some species turn creamy white before maturation.
  • Larvae have a round head with well-developed, dark, chewing mouthparts.
Eggs
  • Smallest size - 0.74 mm (0.03 in.)
  • Largest size - 5 mm (0.22 in.)
  • Many eggs are tiny, smooth, and similar in size to a grain of rice.
  • Mostly elongate and cylindrical. Some species are oblong-oval or ovoid. Other species are cylindrical with tapering at both ends.
  • Translucent to pale yellow, but darken when ready to hatch.
  • Layered egg masses are commonly covered in gelatinous film.

Hosts

 
Citrus hosts

Several beetles have all citrus species and their hybrids listed as hosts including the cucurbit beetle, Diaprepes root weevil, Fuller rose beetle, little leaf notcher, northern citrus root weevil, and southern citrus root weevil. See individual fact sheets for more detailed information.

Non-citrus hosts

Coleopterans have a broad host range that includes weeds, vegetables, field, and flower crops. See individual fact sheets for more detailed information.

Host damage

 
Flowers

Adults may feed on flowers and flower buds.

Fruit

Adults may feed on the fruit and cause distinct scarring.

Leaves

When adults feed, they may create semi-circular to marginal notching on leaves, tender shoots, or petioles that resemble damage caused by caterpillars or grasshoppers. Extensive feeding can lead to defoliation. Gravid female adults commonly lay egg masses on mature leaves.

Roots

Larvae can inflict severe root damage by tunneling or girdling that can lead to increased susceptibility to secondary infections and stunted growth.

Stems

Gravid female adults may lay sticky egg masses on or near the fruit stem.

Trunk

Gravid female adults deposit eggs under the bark of the trunk.

Twigs

Adults may feed on twigs that can lead to secondary infection under heavy infestation.

Biology

 

A female may lay several eggs at a time. Egg masses are deposited directly on or close to the host plant leaves or fruit. Females can protect the egg masses with a white gelatinous cover or deposit them into well-concealed areas like bark crevices. Eggs hatch dependent upon the moisture level. Grub-like larvae typically burrow underground to feed extensively on roots. About one month later, larvae stop feeding and pupate underground. As adults emerge, they begin feeding on the leaves or flowers. Typically adults can be found feeding in the early morning or late afternoon, leaving scattered excrement on the leaves. Adults are most active during mid-summer months.

References

 

(CAPS) Cooperative Agricultural Pest Survey. 2010. Diabrotica speciosa, pp 32-41. In Corn commodity-based survey reference. (http://caps.ceris.purdue.edu/survey/manual/corn_reference).

Davies, F. and L. Jackson. 2009. Pest disease and weed management for the bearing grove, pp. 204-221. In Citrus growing in Florida. 5th ed. University Press of Florida. Gainesville, Florida.

Eaton, E. and K. Kaufman. 2007. Beetles, pp.128-129. In Field guide to insects of North America. Houghton Mifflin Company. New York, New York.

Futch, S., C. McCoy, and H. Nigg. 2002. A guide to soil insect pests identification. University of Florida - Institute of Food and Agricultural Sciences - Extension Publication HS-868. (http://edis.ifas.ufl.edu/hs130).

Gyeltshen, J. and A. Hodges. 2005. Featured Creatures: Citrus longhorned beetle, Anoplophora chinensis (Forster) (Insecta: Coeloptera: Cerambycidae). University of Florida - Department of Entomology and Nematology - Extension Publication EENY-357. (http://entnemdept.ufl.edu/creatures/trees/beetles/citrus_longhorned_beetle.htm).

Knapp, J., H. Nigg, S. Simpson, L. Duncan, J. Graham, J. Peña, C. McCoy, and C. Mannion. 2001. Diaprepes root weevil: A pest of citrus, ornamentals and root crops in Florida. University of Florida - Institute of Food and Agricultural Sciences - Extension Publication ENY645. (http://edis.ifas.ufl.edu/in147).

Triplehorn, C. and N. Johnson. 2004. Coleoptera pp. 365- 379. In Borror and DeLong's Introduction to the study of insects. 7th ed. Brooks/Cole Cengage Learning. Belmonte, California.

Authors

 

Guerrero, S., J.A. Weeks, and A.C. Hodges

 

Citrus Pests
Content last updated June, 2012
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