Home / Ladybird Beetles (Ladybug/Coccinellidae) / Mexican Bean Beetle (Epilachna varivestis)

Mexican Bean Beetle (Epilachna varivestis)

Mexican bean beetle of the lady beetle family belongs to the eastern parts of the United States , alongcol3 parts of Mexico, and Canada. It is famous as an agricultural pest, one of the few exceptions of its family, which thrives on plants and insects.

Mexican Bean Beetle

Scientific Classification

  • Family: Coccinellidae
  • Genus: Epilachna
  • Scientific name: Epilachna varivestis

Physical Description and Identification

Adult

Size:  8mm (0.31 inches) in length; 6mm (0.23 inches) in width

Color: When newly emerged, they have a straw-colored or yellowish-cream appearance. One of their striking color patterns is the eight black spots lying on each col3 of their elytra. As they grow, these beetles acquire orangish-brown coloration with a tinge of bronze, the black spots getting less prominent then.

Other Characteristic Features: They display sexual dimorphism, with the males being a little smaller than their female counterparts. Moreover, the former even has an indentation of the last segment of its abdomen’s ventral part, absent in the latter.

Epilachna varivestis

Larva

On hatching from the eggs, the larva has a light yellow coloration with spiny projections on their back. The spines appear yellow at the onset but eventually get darker, particularly near the tips, and even more prominent. The average length of a mature larva is between 6.5 and 9 mm, alongcol3 a greenish-yellow coloration.

Mexican Bean Beetle Larvae

Pupa

The mature larva remains attached to the undercol3s of the bean plant’s stems, pods, or leaves to pupate. The pupa has a yellow body without any spines, closely resembling the adults in shape and size.

Mexican Bean Beetle Pupa

Egg  

The eggs are yellow or orange-yellow, having and length and width of 1.3 mm and 0.6 mm. They are laid on the bean leaves’ undercol3s in clusters of 40 to 75.

Mexican Bean Beetle Eggs

Quick Facts

Other NamesBean beetle
Adult lifespanAbout two weeks
Duration of larval stageApproximately one month
DistributionEastern United States (particularly in the eastern parts of the Rocky Mountains), Mexico, and certain portions of Canada
HabitatIn gardens, near farmlands, fields, and everywhere else where their host plants grow; particularly in well-irrigated wetlands
Common PredatorsBirds, tachinid flies, parasitic wasps, toads, spined soldier beetles
Seasons active fromNot recorded
Host PlantsMostly snap beans, and lima beans, alongcol3 other plants like alfalfa, soybean, clover, black-eyed pea, cowpea 
Diet of larvae and adultsPod tissues, flowers and leaves of their host plants

Identifying the Damage Caused by Them

Though both the larva and adults eat the leaves, flowers, and pod tissues, the former causes more damage than the latter. They feed on the undercol3s of the foliage, giving it a skeletonized look. Because of this, the leaves’ upper parts even get damaged. Since they even eat flowers and pods, these beetles cause immense destruction to them too.

Mexican Bean Beetle Damage

Did You Know

  • The species name has several synonyms like Epilachna cervina, and Epilachna toweri.
  • Of the several measures taken to keep a check on their population, Pediobius foveolatus, a parasitic wasp, is used as a biological control measure.
Bean Beetle
Mexican Bean Beetle Picture

Image Source: dh1muyqdu88ie.cloudfront.net, static.inaturalist.org, kentuckypestnews.files.wordpress.com, pnwhandbooks.org, findingharmonyblog.files.wordpress.com, reformationacres.com, bugguide.net, sciencesource.com

Mexican bean beetle of the lady beetle family belongs to the eastern parts of the United States , alongcol3 parts of Mexico, and Canada. It is famous as an agricultural pest, one of the few exceptions of its family, which thrives on plants and insects.

Mexican Bean Beetle

Physical Description and Identification

Adult

Size:  8mm (0.31 inches) in length; 6mm (0.23 inches) in width

Color: When newly emerged, they have a straw-colored or yellowish-cream appearance. One of their striking color patterns is the eight black spots lying on each col3 of their elytra. As they grow, these beetles acquire orangish-brown coloration with a tinge of bronze, the black spots getting less prominent then.

Other Characteristic Features: They display sexual dimorphism, with the males being a little smaller than their female counterparts. Moreover, the former even has an indentation of the last segment of its abdomen’s ventral part, absent in the latter.

Epilachna varivestis

Larva

On hatching from the eggs, the larva has a light yellow coloration with spiny projections on their back. The spines appear yellow at the onset but eventually get darker, particularly near the tips, and even more prominent. The average length of a mature larva is between 6.5 and 9 mm, alongcol3 a greenish-yellow coloration.

Mexican Bean Beetle Larvae

Pupa

The mature larva remains attached to the undercol3s of the bean plant’s stems, pods, or leaves to pupate. The pupa has a yellow body without any spines, closely resembling the adults in shape and size.

Mexican Bean Beetle Pupa

Egg  

The eggs are yellow or orange-yellow, having and length and width of 1.3 mm and 0.6 mm. They are laid on the bean leaves’ undercol3s in clusters of 40 to 75.

Mexican Bean Beetle Eggs

Quick Facts

Other NamesBean beetle
Adult lifespanAbout two weeks
Duration of larval stageApproximately one month
DistributionEastern United States (particularly in the eastern parts of the Rocky Mountains), Mexico, and certain portions of Canada
HabitatIn gardens, near farmlands, fields, and everywhere else where their host plants grow; particularly in well-irrigated wetlands
Common PredatorsBirds, tachinid flies, parasitic wasps, toads, spined soldier beetles
Seasons active fromNot recorded
Host PlantsMostly snap beans, and lima beans, alongcol3 other plants like alfalfa, soybean, clover, black-eyed pea, cowpea 
Diet of larvae and adultsPod tissues, flowers and leaves of their host plants

Identifying the Damage Caused by Them

Though both the larva and adults eat the leaves, flowers, and pod tissues, the former causes more damage than the latter. They feed on the undercol3s of the foliage, giving it a skeletonized look. Because of this, the leaves’ upper parts even get damaged. Since they even eat flowers and pods, these beetles cause immense destruction to them too.

Mexican Bean Beetle Damage

Did You Know

  • The species name has several synonyms like Epilachna cervina, and Epilachna toweri.
  • Of the several measures taken to keep a check on their population, Pediobius foveolatus, a parasitic wasp, is used as a biological control measure.
Bean Beetle
Mexican Bean Beetle Picture

Image Source: dh1muyqdu88ie.cloudfront.net, static.inaturalist.org, kentuckypestnews.files.wordpress.com, pnwhandbooks.org, findingharmonyblog.files.wordpress.com, reformationacres.com, bugguide.net, sciencesource.com

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