Video-recordings were made of adult spotted lanternflies, Lycorma delicatula, taking flight from apple trees in an orchard in northeast Pennsylvania in September, 2017 during a mass dispersal flight event involving thousands of adults. The trajectories of adults flying upwind in straight and level or gradually descending flight allowed them to traverse only up to ca. 40 m in a single flight-bout. Many did not make it to trees or bushes that were at even shorter distances than this and they landed in the grass. Flight tracks of 162 adults launching themselves into the wind from the upper branches of apple trees were video-recorded in plan view from below by a camera placed on the ground aimed straight up at the sky. The tracks were then digitized and analyzed using a triangle of velocities technique to determine the degree to which the adults were progressing in a directly upwind flight track, with the wind vector experienced by each adult calculated from the adults’ flight track itself. Average airspeeds of upwind-flying L. delicatula had been previously measured in another group of adults and shown to not vary with wind speed. The headings (direction of thrust) of adults in the video frames were determined by matching the image of the adult in each video frame with a template image of a pinned adult of a known distance from the camera and heading. Matching the body axis in this way works for this species because the adults flying in these elongated fairly straight flight paths did so with forewings spread out flat to the ground with little discernable roll. Having determined airspeed and heading plus ground speed and track for each set of images allowed the third side of the triangle of velocities — the wind velocity vector — to be calculated for each flying adult at whatever altitude or lateral location in the camera’s field of view it was flying. Adult L. delicatula were found to head upwind in flight at 10.7° off the wind line to produce resulting track angles of progression over the ground averaging 30.9° off the wind line due to this discrepancy between their headings and the wind velocities into which they were flying. The wind velocity vectors provided by a ground-based anemometer during the periods each adult was flying through the video frames deviated from the wind velocity vectors calculated using the triangle of velocities technique by nearly 22° and were 50% lower in wind speed than the calculated vectors taken at the higher altitudes and locations each adult was flying. The triangle of velocities technique might provide a new way of using certain species of insects as free-flying anemometers to take wind velocity readings at different heights and spatial locations that are not attainable through the use of ground-based anemometers.

中文翻译：

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2017 年宾夕法尼亚州大规模散播飞行期间斑点灯笼蝇 (Lycorma delicatula) 的无定向飞行趋势分析

2017 年 9 月，在一次涉及数千名成年人的大规模散播飞行事件中，成年斑点灯笼蝇 Lycorma delicatula 从宾夕法尼亚州东北部果园的苹果树上飞行。成虫在逆风方向上直线水平飞行或逐渐下降飞行的轨迹使它们只能穿越约 。单次飞行 40 m。许多人没有到达比这更近的树木或灌木丛，他们落在了草地上。162 名成虫从苹果树的上枝迎风而起的飞行轨迹被放置在地面上的直视天空的摄像机从下方的平面视图中记录下来。然后使用速度三角形技术对轨迹进行数字化和分析，以确定成虫在直接逆风飞行轨迹中前进的程度，每个成虫经历的风向量从成虫的飞行轨迹本身计算。逆风飞行的 L. delicatula 的平均空速先前已在另一组成年人中测量过，并且显示不随风速变化。视频帧中成人的航向（推力方向）是通过将每个视频帧中的成人图像与距离摄像机和航向已知距离的固定成人的模板图像进行匹配来确定的。以这种方式匹配体轴适用于该物种，因为在这些细长的相当笔直的飞行路径中飞行的成虫是这样做的，前翅平展在地面上，几乎没有明显的滚动。确定了每组图像的空速和航向加上地速和航迹后，就可以为每个飞行的成年人计算速度三角形的第三边——风速矢量——在相机视野中的任何高度或横向位置正在飞行。成年 L. delicatula 被发现在飞行中以偏离风线 10.7° 的位置逆风行驶，从而在地面上产生平均偏离风线 30.9° 的轨迹角，这是由于它们的航向和它们所处的风速之间存在差异飞行。在每个成年人飞过视频帧期间，地面风速计提供的风速矢量与使用速度三角技术计算的风速矢量相差近 22°，风速比计算的低 50%在每个成年人飞行的更高海拔和地点拍摄的矢量。速度三角技术可能提供一种新方法，使用某些种类的昆虫作为自由飞行的风速计，在不同高度和空间位置获取风速读数，而这些读数是通过使用地面风速计无法实现的。