Asian Longhorned Beetle Life Cycle

Life Cycle Stages

The life cycle of the Asian longhorned beetle has four stages of development called complete metamorphosis. Complete metamorphosis development includes four stages of development:

  1. Egg
  2. Larva
  3. Pupa
  4. Adult
life cycle chart

The egg is laid by the female Asian longhorned beetle in a notch that she chews into the bark of a tree. After burrowing, the female beetle then lays a single egg. One female will lay eggs at multiple sites, with the possibility of a single beetle laying up to 100 eggs.

When the egg hatches, the newly emerged larva feeds upon the inner tissues of the tree and branch trunks in the vicinity of the burrow site. As it increases in size, the growing larva turns and burrows its way into the heart of the tree.

The larva has 5 stages of development known as “instars.” They can grow up to 5 cm prior to entering the pupation stage into adulthood. The life cycle of the Asian longhorned beetle crosses from one development season into the next, with the insect overwintering as a larva in the heart of the tree.

Before pupating, the larvae turn and make their way toward the exterior bark of the infested tree, where they establish into a pupal cavity where they will finish development into the adult form. The larva then enters the pupation stage and emerges in the adult form after a month.

Once in adult form, their feeding habits decrease in that they do not feed as much as when in the stages of development. Adults will continue to reproduce and develop from the tree until the weather turns cooler or the first hard frost of the fall occurs.

In northern areas, eggs laid in the late season may overwinter as eggs. Once mating has occurred, the female will start the chewing process into the tree to lay the egg. The male is present until this process occurs.

Encounters & Concerns

The Asian longhorned beetle’s life cycle mostly occurs under the host tree’s bark, so homeowners will not see the egg, larva, or pupal stage. However, once they have matured into adults, their presence becomes known since adult beetles exit infested host trees by chewing holes in the tree and emerging.

Adult beetles are generally most active from late spring into the late fall, depending upon the conditions. Other than the physical presence of the adults, homeowners may also notice frass (sawdust) around the base of infested trees and in the crotch where limbs meet the tree’s trunk.

Concerns created by this tree pest are immense since Asian longhorned beetles are known to cause damage to maple and many other hardwood tree species in both residential and forested areas. The elimination of the beetles is through removal and destruction of infested trees and establishing quarantine areas to minimize the possible transfer of the beetle’s eggs, larvae, and pupae from one location to another.