The Emerald Ash Borer, also referred to as E.A.B. in shorthand, is a highly destructive and invasive beetle that originates from Northeastern Asia.  After its introduction in the United States, it has been a large focus of study due to its single-handed demolition of the American Ash Tree Species.  Being a beetle, it falls under the Order Coleoptera and due to its distinctive metallic colors, these unique beetles belong to the Family Buprestidae.  Emerald Ash Borers are ranked in the Genus Agrilus which is well known for containing several species of “jewel beetles.”  The Species is planipennis, making the Emerald Ash Borer’s scientific name Agrilus planipennis. (Cameron, 2020)

 

The life stages of these beetles are analogous to all other beetles starting with eggs hatching into larvae and larvae pupating into sexually mature adults.  Emerald Ash Borer eggs look like very small discs (white or dark if fertile) and are laid by females between the cracks of Ash tree bark in the late spring.  Once the eggs hatch, about a week to ten days after being laid, larvae emerge and look like small white worms.  In the larval stage, they will eat the tree’s phloem, xylem, and cambium causing much harm to the host tree’s transport systems.  Here the larva will feed, develop, and eat in long twisting ‘galleries’, until they are ready to pupate for one to two weeks until they are fully developed adults.  Adults then emerge from Ash trees from ‘D’ shaped exit holes in the spring, living for about two or three weeks in order to mate and lay eggs again.  These beetles are constantly mating during the time they are out of the tree and lay about 60 to 100 eggs on average.  Adult beetles then turn to eating the Ash tree leaves for nutrients but still cause significantly more damage to the trees in their larval stages.  Emerald Ash Beetle mature adults are a bright metallic green color but half an inch or smaller making them extremely difficult to find and identify infestations until Ash tree hosts are already doomed.  The entire life cycle is one year long. (Ndiaye, 2020)

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Eggs:

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Larva:

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Adult:

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Tree-killing damage is achieved in the larval stage when larvae chew through trees’ bark, phloem, and xylem in order to feed and grow.  These tunnels created by the larva are called galleries and cause significant damage to trees and their ability to transport water and nutrients.  The Emerald Ash Borer beetle causes much more damage than other beetles tend to because they have the ability to tunnel deep into a tree to protect it from cold and harsh winters, as well as lacking traditional predators which help keep beetle populations in check.  Large Emerald Ash Borer beetle populations tend to get out of hand really fast, infesting, taking over, and killing Ash trees completely in a really quick time.  Small young Ash trees can die in one to two years after the first beetle’s ingress, while larger trees often die within three or four years after the first borer arrives.  Due to their small size, unnoticeable qualities, and habits of tunneling deep into a tree make it really difficult to spot tree infections and invasions until it is much too late for the tree itself.  (Sydor, 2007) Coming from Northeast Asia, The Emerald Ash Borer has been quickly making its way west after being introduced in Southeastern Michigan.  The spread of this beetle can be blamed on humans directly for being responsible for transporting both wood and other plants long distances as well as the frequent use of Ash trees in urban infrastructure. (Kocher, 2022)

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One particularly interesting reproductive behavior is that scientists recently discovered that Emerald Ash Borers can also complete their life cycles on trees from the Oleaceae Family.  This makes EAB a potential future threat to Olive tree growers as well. (Ndiaye, 2020)

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Life Stages (not including egg)

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