genus relatively short bodied stout stick insects native far western united_states genus described based observations species compared stick insects order genus considered basal earliest branch phylogenetic tree includes emphasize status stick insects included described species including species engaged sexual reproduction million years longest known period insect description differ segments stick insects relatively small stout bodies look somewhat like order cryptic coloration camouflage walking sticks night spend daytime resting leaves bark plants feed colors primarily green gray brown patterns stripes scales dots match typical background form researchers studying presence absence dorsal stripe suggested independently evolved times species adaptation needle like leaves species dorsal stripe host plant needle like foliage thirteen species seven feed plants rest day host plant trunk leaves bodies brown gray tan species green feed needle like foliage feed hosts species exhibits striped populations depending host plant form clearly illustrates camouflage function stripe earliest ancestors species fed plants belonging genera eventually diverged distinct specialist host plant preference prefers feed prefers feed possesses white dorsal stripe adaptation blend needle like leaves plant broad leaves smaller wider head shorter legs characteristics genetically inherited interpreted early stages process eventually separate species reproductive isolation achieved moment capable producing viable offspring considered single species life cycle reproduction eggs soft long lid like structure end emerge females use particles dirt previously coat eggs eggs stick insects including attractive ants carry away feed egg leaving rest egg intact hatch emerging passes seven reaching adulthood males sexual species consistent pattern behavior male climbs female short display waving proceed mate rejection female possible uncommon male rides female days behavior referred guarding female species females reproduce producing viable eggs male participation according oldest insects good evidence long periods time heads team researchers found species reproduction years million years habitat geographic range limited mountainous regions western north_america found primarily california neighboring states oregon nevada arizona northern mexico primarily feeding host plants found host plants different species include douglas fir white fir oak mountain phylogeny general phylogenetic relationships law species marked female classification member family clade considered basal order scientists believe type stick insects represent earliest branch phylogenetic tree gave rise stick insects distinction referenced given species described addition species known exist
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