Accumulation of Non-Target Arthropods on Sticky Tree Bands
We monitored the accumulation of non-target arthropods and leaf litter on tree bands used for cankerworm control during a 4-week period in the autumn of 2013 prior to the beginning of cankerworm emergence. Accumulation of non-target arthropods and leaf debris may reduce the efficacy of tree bands in controlling cankerworms and harm non-target tree-dwelling arthropods. Ten oak trees were randomly selected from a set of 17 banded trees along one walkway on Davidson College in the Town of Davidson, NC, where cankerworms have recently become more abundant. Banding is known to capture high numbers of certain forest pests such as fall cankerworms (Alsophila pometaria (Harris)), although conclusive evidence that banding reduces defoliation is lacking. We found that non-target arthropods and leaves accumulated at a steady rate prior to emergence of cankerworm adults. Many predatory arthropods, including spiders, assassin bugs, praying mantids, lacewing larvae, and ladybird beetles were observed entangled and walking free on bands outside the Tanglefoot-covered area. We found indirect evidence for predation or consumption of trapped arthropods off of bands by birds and predatory insects. Early installation of tree bands prior to cankerworm adult emergence potentially damages the rest of the arthropod community.Abstract

Density of insects and spiders on tree bands, plus the total of all arthropods observed (a) and arthropod daily loss rate (b). In (a) the solid line represents the best fit curve for spiders, the dotted line represents the best fit curve for insects, and the dashed line represents the best fit curve for arthropods. Data in (b) are from sections of the bands photographed on a regular basis. Error bars in (a) and (b) represent 1 standard error averaged over 10 oak trees in the study.

Leaf litter accumulation in sections of the bands photographed on a regular basis. Error bars represent 1 standard error averaged over 10 oak trees in the study.