et les ▁and ▁we ev ils , ▁and ▁met all ic ▁flat - head ed ▁bor ers . ▁ ▁E col ogy ▁Wood bor ing ▁be et les ▁most ▁often ▁attack ▁dying ▁or ▁dead ▁trees . ▁In ▁forest ▁settings , ▁they ▁are ▁important ▁in ▁the ▁turn over ▁of ▁trees ▁by ▁c ull ing ▁weak ▁trees , ▁thus ▁allowing ▁new ▁growth ▁to ▁occur . ▁They ▁are ▁also ▁important ▁as ▁primary ▁decom pos ers ▁of ▁trees ▁within ▁forest ▁systems , ▁allowing ▁for ▁the ▁rec y cling ▁of ▁nut ri ents ▁locked ▁away ▁in ▁the ▁relatively ▁decay - res il ient ▁wo ody ▁material ▁of ▁trees . ▁To ▁develop ▁and ▁reach ▁m atur ity ▁wood bor ing ▁be et les ▁need ▁nut ri ents ▁provided ▁by ▁fung i ▁from ▁outside ▁of ▁the ▁inhab ited ▁wood . ▁These ▁nut ri ents ▁are ▁not ▁only ▁assim il ated ▁into ▁the ▁be et les ' ▁bodies ▁but ▁also ▁are ▁concentr ated ▁in ▁their ▁fr ass , ▁contrib uting ▁to ▁soil ▁nut ri ents ▁cycles . ▁Though ▁the ▁vast ▁majority ▁of ▁wood bor ing ▁be et les ▁are ▁e colog ically ▁important ▁and ▁econom ically ▁ben ign , ▁some ▁species ▁can ▁become ▁economic ▁p ests ▁by ▁attack ing ▁relatively ▁health y ▁trees ▁( e . g . ▁Asian ▁long horn ▁be et le , ▁emer ald ▁ash ▁b orer ) ▁or ▁by ▁inf est ing ▁down ed ▁trees ▁in ▁l umber ▁yards . ▁Species ▁such ▁as ▁the ▁Asian ▁long horn ▁be et le ▁and ▁the ▁emer ald ▁ash ▁b orer