Animals often compete for resources and territory. Differences in size and body condition often play a crucial role in determining the outcome of these competitions. Web spiders not only create very costly semipermanent territories in the forms of their webs but have been shown able to gather myriad information from chemical cues present on silk. Furthermore, some web spiders are known to invade the webs of conspecifics in lieu of creating their own. We examined whether two pholcid spiders, Pholcus manueli and Pholcus phalangioides, use chemical information about the size and body condition of the web owner to inform their decisions when invading a foreign web. Specifically, we examined whether spiders could gather information about the size and hunger level of a conspecific and whether this information influenced their web-invading behaviour. We also examined whether washing webs with ethanol could remove these effects. We introduced spiders to webs built by conspecifics and recorded their latency to invade the webs. Pholcus manueli invaded webs built by larger conspecifics more slowly while P. phalangioides did not alter invasion latency to larger spiders' webs. Washing webs with ethanol removed this effect. Neither species’ behaviour was affected by the hunger level of the web builder. Our results show that P. manueli can determine the size of a conspecific from chemical cues attached to silk and adjust their web invasion behaviour accordingly, but that P. phalangioides does not adjust its behaviour in response to such cues. Importantly, our web-washing results support that chemical cues and not web structure influenced invasion behaviour of P. manueli, giving us a powerful tool for future research. The species level differences suggest separate behavioural strategies between the two similar species and that these strategies may influence the outcome of competitions between the two.

动物经常争夺资源和领土。尺寸和身体状况的差异通常在决定这些比赛的结果中起着至关重要的作用。网络蜘蛛不仅会以网络形式创建非常昂贵的半永久性领土，而且还被证明能够从存在于丝绸上的化学线索中收集大量信息。此外，已知某些蜘蛛网会入侵特定物种的蜘蛛网，而不是创建自己的蜘蛛网。我们检查了两种磷蜘蛛，即Phocus manueli和Pholcus phalangioides，请在入侵国外网站时使用有关网站所有者的大小和身体状况的化学信息来告知他们的决定。具体来说，我们研究了蜘蛛是否可以收集有关特定物种的大小和饥饿程度的信息，以及该信息是否影响了其入侵网络的行为。我们还检查了用乙醇洗涤纤维网是否可以消除这些影响。我们将蜘蛛引入到由特定物种构建的网络中，并记录了它们入侵网络的潜伏期。Phocus manueli入侵由较大同种异种构建的网的速度较慢，而P. phalangioides并未改变对较大蜘蛛网的入侵潜伏期。用乙醇洗涤纤维网可消除这种影响。网络构建者的饥饿程度都不会影响这两种物种的行为。我们的结果表明P. manueli可以从附着在丝绸上的化学线索确定同种菌的大小，并据此调整其网状入侵行为，但是phalangioides不能对这种线索做出反应来调整其行为。重要的是，我们的网洗结果支持化学提示而不是网结构影响了马氏假单胞菌的入侵行为，从而为我们的未来研究提供了强大的工具。物种水平差异表明两个相似物种之间存在不同的行为策略，并且这些策略可能会影响两者之间的竞争结果。