Order Coleoptera - Beetles


Order Coleoptera
This is the largest order in the class Insecta with over 250,000 described species.  Obviously, with this many species, there is a wide range of diversity in this order with respect to size, morphological characters, biology, and behavior.  However, the order is typically characterized by a pair of elytra (hardened front wings) and a pair of membranous hind wings.  They have chewing mouthparts that may be slightly modified for various functions and undergo complete metamorphosis.  Beetles occur in nearly every type of habitat, from the desert to aquatic systems, and feed on various plant and animal materials.



Weevils (Curculionidae)
This is the largest family of insects and more than 3,000 species of weevils occur in North America.  Nearly all weevils are phytophagous.  The weevils are easily recognized by having the head prolonged into a snout, with chewing mouthparts at the tip of the snout.  They often have elbowed antennae.



Leaf Beetles (Chrysomelidae)
The leaf beetles are phytophagous that are typically oval in shape and often brightly colored.  The antennae are obvious, but typically less that half as long as the body.  Their tarsal formula (number of tarsomeres on fore, mid, and hind leg) is apparently 4-4-4, but is actually 5-5-5.  They are similar to the longhorned beetles, except that the antennae are typically shorter and the eyes are not notched.



Lady Beetles (Coccinellidae)
Lady beetles are often recognized by their distinctive coloration and oval body shape.  The head is typically partially or entirely concealed by the pronotum.  Their antennae are short with a three- to six-segmented club.  Their tarsal formula is apparently 3-3-3, but actually 4-4-4.  Most adult and immature lady beetles are generalist predators and have been implemented in biological control programs.  The adults often overwinter in large aggregations.



Scarab Beetle (Scarabaeidae)
Scarab beetles are relatively stout-bodied beetles that vary greatly in size.  There are about 1,400 scarab species in North America, many of which cause considerable damage to various plants.  The tarsi are all five-segmented (5-5-5).  The antennae have 8-11 segments and are lamellate, which enable them to hold the segments of the club tight together or expanded.  Common scarabs include the May/June beetles, masked chafers, and Japanese beetles.



Tiger Beetles (Cicindelidae)
Adults tiger beetles are often metallic with distinctive color patterns.  Their characteristic shape is often used in identifying them.  The head is typically as wide or wider than the pronotum.  They have threadlike antennae and long slender legs.  These insects are very fast and often difficult to collect.  Their agility and strong mandibles make them well-adapted for their predaceous life style.  The endangered Salt Creek Tiger Beetle is a member of this family.  Some authorities place the tiger beetles in the same family as the ground beetles (Carabidae).



Ground Beetles (Carabidae)
The carabids are similar to the tiger beetles and are sometimes considered to be in the same family.  Ground beetles can be recognized by having a head that is narrower that the pronotum.  They are usually black and shiny, but a few species are brightly colored.  Like the tiger beetles, they have long slender legs.  Nearly all species are predaceous as larvae and adults



Longhorned Beetles (Cerambycidae)
Longhorned beetles are identified by having antennae that are usually at least half as long as the body and often longerThe body is typically cylindrical and elongatedThe eyes are often notched around the antennae.  All longhorned beetles are phytophagous, being primarily wood-boring as larvae and flower-feeding as adults.  The tarsi are similar to the chrysomelids, apparently 4-4-4.

Breaking Entomological News...

  • Insect Science major Earl Agpawa (conducting undergraduate research with Joe Louis and Eileen Hebets) was named the 2020 winner of the ESA’s Plant-Insect Ecosystems Undergraduate Student Achievement Award.This is a national award that recognizes outstanding accomplishments in entomology by an undergraduate student working with insect-plant interactions. Congratulations, Earl!
  • PhD student Sajjan Grover (mentored by Joe Louis) was named the 2020 winner of the ESA’s Plant-Insect Ecosystems Kenneth and Barbara Starks Plant Resistance to Insects Graduate Student Award. This is a national award recognizing a graduate student for outstanding work in the area of host plant resistance. Congratulations, Sajjan!
  • Dr. Joe Louis receives a grant to study resistance in sorghum to fall armyworm
  • Check out the Emerald Ash Borer Resource Center, and our Emerald Ash Borer Look-Alike Insects Sheet - Be Sure Before You Treat!