Behavioural responses of the leaf-chewing guild to the presence of Eriocrania mines on silver birch (Betula pendula )

1. Interactions between early season leaf-miners from the genus Eriocrania Zeller (Eriocraniidae: Lepidoptera), and the leaf-chewing guild of silver birch (Betula pendula Roth) were investigated. 2. Field observations indicated that a negative association between damage caused by Eriocrania, and leaf-chewers could be observed under certain conditions, namely at higher damage densities in the final week of mine development on trees with relatively high densities of mines. 3. Experimental manipulation of Operophtera brumata L. (Geometridae: Lepidoptera) densities in the field confirmed the negative association between established mines of Eriocrania, and this species of free-living folivore. 4. The behaviour of O. brumata was modified further in the presence of mines. On branches where mined leaves were present, O. brumata larvae consumed a larger proportion of leaf tissue, by continuing to feed on the same leaf longer rather than shifting to a new leaf. Increased consumption may indicate some modification of leaf quality beyond the leaves occupied by Eriocrania. Alternatively, it may indicate an association between Eriocrania, and higher quality leaf material.