larvae were collected opportunistically from tammany creek , nez perce co. , i d ( 46 21.51.51 n , 117 03.32.05 w ) , a perennial , undammed creek approximately 13  m in width and roughly 10  km in length . tammany creek drains into the snake river approximately 770  km from the confluence of the snake and columbia rivers . we surveyed the study area ( 1  km in length ) on foot and collected odonates by drag net from 15 february 2012 to 12 march 2012 . upon collection , larvae were transported to lewis - clark state college and housed in 50-ml plastic vials with a 3-mm - diameter dowel for perching . larvae were measured with a millimeter rule for total body length and head width and maintained on a photoperiod of 14:10 ( l : d ) h cycle at an ambient air temperature of 22c . vivida head 24.5  mm , body 619  mm ; a. palmata head 48  mm , body 2335  mm . behavior trials were conducted in 250-ml containers with filtered tap water and a singular 3-mm - diameter perch . one shrimp was placed in the container , as alternative prey , 1  min after simultaneously placing both odonates in the container . vivida head 34  mm , body 1117  mm ; a. palmata head 48  mm , body 2335  mm . to evaluate whether the observed behaviors were species specific , we tested a. palmata and ar . animals used in congeneric trials ( not diagrammed ) were matched for total body length as closely as possible ( 31 ar . vivida , a previously undescribed luring behavior was observed by either a. palmata or ar . that luring behavior was demonstrated , the a. palmata attempted , unsuccessfully , to capture the shrimp prior to the luring behavior . luring behavior was initiated only when the odonates had entered into the field of view of one another . once the a. palmata and ar . vivida had oriented toward each other , a brief period ( 3060  s ) of no visible movement ensued . in four of five trials d ) sequence of points in luring abdominal movement by a. palmata during a. palmata ( large ) versus ar . . 
 abdominal movement to the side and exposure of the abdomen of a. palmata to ar . vivida changed position to place the abdomen of a. palmata directly in the field of view ( fig . this behavior consisted of 710 movements of the abdomen within approximately 2  s ( fig . ( a  d ) sequence of points in luring abdominal movement by a. palmata during a. palmata ( large ) versus ar . . abdominal movement to the side and exposure of the abdomen of a. palmata to ar . ar . vivida changed position to place the abdomen of a. palmata directly in the field of view ( fig . this behavior consisted of 710 movements of the abdomen within approximately 2  s ( fig . vivida luring a. palmata was observed . the following sequence of events details that observation ( fig . 2a).the abdomen was then fully moved to the opposite side of the body in a slow motion ( 2  s ) and held on the other side of the body for approximately 8 s ( fig . 2b).step 2 was repeated to the initial side of luring . at this point , ar . vivida positioned its abdomen directly behind its head and slowly continued movement toward head of a. palmata . vivida attempted to capture a. palmata at its head.upon being struck , a. palmata slowly retreated.ar . vivida continued attempts at luring a. palmata , with rapid abdominal movements to the initial side for approximately 5  s. while luring , ar . vivida slowly approached the retreating a. palmata.the sequence was broken as a. palmata used abdominal thrusts to propel itself away and over ar . the abdomen was then fully moved to the opposite side of the body in a slow motion ( 2  s ) and held on the other side of the body for approximately 8 s ( fig . step 2 was repeated to the initial side of luring . at this point , ar . vivida positioned its abdomen directly behind its head and slowly continued movement toward head of a. palmata . vivida continued attempts at luring a. palmata , with rapid abdominal movements to the initial side for approximately 5  s. while luring , ar . the sequence was broken as a. palmata used abdominal thrusts to propel itself away and over ar . vivida . in the other 13 of 18 a. palmata versus ar . , a. palmata actively pursued the shrimp prey item , catching and consuming the prey without attacking the ar . vivida positioned itself at the bottom of the chamber and remained motionless for the entirety of the trial . vivida pursuing the prey . in all of these trials , the a. palmata captured and consumed vivida attempting to consume the prey item after the a. palmata had caught and began consumption . in this instance , the ar . vivida was consumed by the a. palmata following consumption of the prey . in one trial , ar . vivida actively attacked and consumed the prey , and a. palmata remained motionless in the chamber . in every congeneric trial vivida , 12 a. palmata versus a. palmata ) , there were no instances of attack , luring , or attempted consumption of the congeneric by either animal . in our trials , luring occurred only when a head - to - head orientation was present . this is the same orientation described in the well - known agonistic behavior of many larval odonates ( corbet 1999 ) . however , in contrast to previously described agonistic behaviors , predatory luring occurred between different odonate families with a different repertoire of movements ( figs . 1 and 2 ) and typically ended in consumption of the prey . in trials where luring was not displayed a caudal attack by either species typically resulted in one of two possible scenarios : 1 ) removal of lamellae of ar . vivida and subsequent retreat and avoidance of further attack by prey and 2 ) prey being grasped and subsequent retaliatory bites and aggression resulting in injury to the predator ( e.m . , personal observations ) . these two scenarios , we believe , are the reasons for the head - to - head orientation that has been demonstrated as critical for the luring to occur . the caudal luring by the predator caused the lured individual to change orientation slightly to ensure that a successful attack was achieved . the exaggerated slow swaying of the caudal region caused the lured individual to change orientation . the subsequent rapid movements of the caudal region resembled that of the preferred prey in this environment , the freshwater shrimp , which further provoked the lured individual to investigate . the movement of the lured individual from the head - to - head orientation to the more vulnerable position of focusing on the lure provided the predator an opportunity to strike at the prey . we believe that more instances of predatory luring would have been observed had the time duration of the trials been longer than 7  min . all animals used in the trials were nave , not having been involved in any trials previously . we can not comment on the experience of the animals in the field before capture ; however , all animals were housed individually for 3 weeks before trials were conducted . the luring demonstrated by ar . vivida , even though consumption was not achieved ( although a strike at the head of the much larger a. palmata did occur ) , may indicate that this behavior can be used in situations other than predation . vivida is similar to the agonistic behavior of other coenagrionidaen odonates ( rowe 1992 ) , several differences exist . 3 ) the behavior displayed by ar . vivida to physically lure the larger a. palmata close to the ar . vivida versus a. palmata with closely matched sizes will help elucidate whether this behavior is predatory or used to ward off potential predators . although there was no luring of a. palmata by other a. palmata , similarity of ar . the possibility of predation by a congeneric may induce the larger dragonfly to lure the smaller but morphologically similar damselfly to a position in which a fatal attack is much easier and much more likely . vivida and a. palmata at this locale creates the possibility that large larvae are likely to encounter smaller conspecifics .