Adelges tsugae Annand (Hemiptera: Adelgidae), a nonindigenous insect pest of hemlock (Tsuga spp.) (Pinaceae) in eastern North America, spends most of its life cycle within an ovisac, which resembles a woolly white mass on twigs. We evaluated the probability of detecting adelgid wool with Velcro®-covered balls when taking an increasing number of samples per tree (field sampling) and number of trees per simulated stand. We examined the relationship between the detection of adelgid wool using this technique and the incidence of A. tsugae-infested twigs by sampling lower-crown branch tips of the same trees. We found that the probability of detecting wool with ball sampling increased with number of ball samples per tree, with number of trees per simulated stand, and with increasing incidence of ovisacs in the lower crown. When sampling an individual tree, we found that 20 ball samples per tree achieved a targeted precision level of 0.75, but when sampling a stand, we found that 10 ball samples per tree took the least time for the range of simulated A. tsugae infestations we tested. These sample sizes are recommended for detection of A. tsugae infestations on an individual tree and in a hemlock stand.

Adelges tsugae Annand（半翅目：Adelgidae）是北美东部铁杉（Tsuga spp.）（松科）的一种非本土害虫，其大部分生命周期都在卵囊内度过，卵囊类似于树枝上的白色羊毛团。我们评估了当每棵树（现场采样）和每个模拟林分的树木数量增加时，用 Velcro ®覆盖的球检测到 adelgid 羊毛的概率。我们研究了使用这种技术检测 adelgid 羊毛与A. tsugae发病率之间的关系- 通过对同一棵树的下冠分枝尖端进行采样来检测受感染的树枝。我们发现用球采样检测羊毛的概率随着每棵树的球样本数量、每个模拟林分的树木数量以及较低树冠中卵囊发生率的增加而增加。在对一棵树进行采样时，我们发现每棵树 20 个球样本达到了 0.75 的目标精度水平，但是在对一个林分进行采样时，我们发现每棵树 10 个球样本在我们模拟的A. tsugae侵染范围内花费的时间最少测试。建议使用这些样本量来检测单个树木和铁杉林中的A. tsugae侵染。