**3. Results**

In March, all webs receiving the two control treatments had been substantially restored to their previous structure 24 h later, whereas none of the permethrin-treated webs were substantially restored (*p* = 1.69 × <sup>10</sup>−10; *X*<sup>2</sup> = 30; 2 df). Six of the 15 permethrin-treated webs had been partially restored, and the rest were in the same torn condition as the day before. Of those webs that had been rebuilt, the mesh areas were, on average, just 42% of their original size (*p* = 0.005, t = 4.13, df = 6.8, paired T-test, unequal variance, 2-tailed). Visual inspection revealed that spacing of the adhesive spiral mesh strands was wider than on a normal web (Figure 2F). Most spiders on the permethrin-sprayed webs remained on the web, though several disappeared, having either abandoned the web or been predated.

In June, when we treated webs in preparation for mosquito capture, all control webs were substantially restored within 24 h, whereas just 29% (6 of 21) of the spiders on permethrin-treated webs had substantially restored their webs (*p* < 0.0001; Fisher's Exact Test). All permethrin-treated webs had been restored after three days, showing the interference at this dose was temporary.

The day after treating the webs in June, we tested the webs and spiders for mosquitocatching ability. Permethrin reduced the number of mosquitoes captured by 71%, independent of the reduced web area (Figure 3). Permethrin-treated webs were less effective at retaining the mosquitoes that struck them than the control webs; (*p* = 0.00024; t = 4.44, 15 df). Mosquitoes adhered to each of the 16 control webs for at least three seconds, and the resident spider seized a mosquito in each web. In the 21 permethrin-treated webs, we managed to stick a mosquito in what remained of 86% (18) of the webs; three webs could not retain a mosquito at all. Spiders on treated webs were less likely to seize a mosquito that did stick than spiders on control webs (*p* < 0.0001; Fisher's Exact test). In 67% of the webs that held a mosquito for at least 3 sec but that had not been substantially repaired (12 of 18), none of the spiders seized the mosquito. In the 21% of webs that were substantially reconstructed, each spider seized the mosquito immediately. Mosquitoes not seized by the spiders eventually wiggled free.

**Figure 2.** Side by side comparisons of spider webs before (**A**,**C**,**E**) and after (**B**,**D**,**F**) the residing orchard spiders were exposed to treatments. The control treatments (**A**–**D**) had no adverse effect on web reconstruction. For the first day after application, permethrin treatment (**E**,**F**) interfered with the resident spider's ability to reconstruct a normal web. The few webs that were partially reconstructed (6 of 15) had a significantly smaller web area, and irregular and wide spacing of adhesive spiral strands visible in the permethrin treatment after 24 h (**F**).

**Figure 3.** Spiders on permethrin-treated webs captured far fewer mosquitoes than those on control webs.
