User:KoA/sandbox: Difference between revisions

Newly hatched larvae bore through the bark to the phloem and outer layer of new sapwood where they feed until the weather gets too cold in the fall. There are four stages of larval development (instars). As they feed, the larvae create long serpentine galleries filled with [[frass]], which enlarge in width as they grow. Larvae are creamy white, and dorso-ventrally flattened. When fully mature, fourth-instar larvae are 26 to 32&nbsp;mm long. Their head is mostly retracted into the prothorax with only the dark brown mouthparts visible. The prothorax is enlarged, with the mesothorax and metathorax more narrow. Larvae have 10 bell-shaped abdominal segments and a pair of small brown structures called urogomphi, which are characteristic of all larvae in the genus Agrilus.<ref name="USDA-APHIS-ARS-FS"/>

 

In the fall, mature fourth-instar EAB larvae excavate pupal chambers in the sapwood or outer bark where they fold into overwintering “J-shaped larvae”. In the spring, the J-shaped larvae shorten into prepupae then shed their cuticle to become naked pupae. Pupae

are initially creamy white, but the eyes turn red and the body begins to darken as they develop. To emerge from ash trees, adults chew D-shaped exit holes through the bark and are capable of immediate flight upon emergence. EAB larvae that are immature as cold weather arrives in the fall will simply overwinter in their larval gallery. Larger larvae complete development the following spring, whereas smaller larvae may require another summer of feeding to complete development.<ref name="USDA-APHIS-ARS-FS"/>

 

 

* Lack of natural enemies

* Plant resistance