by Carl Strang
Yesterday I reported on one of my herbivory studies at Maple and Meacham Grove Forest Preserves. Today I have the data for the first part of the other study, a decades-long following of 4 leaf miner genera in sugar and black maples in the understories of the two forests. While attempting to photograph confused ground crickets at Warrenville Grove, I had noticed a high incidence of tent mines, produced by the micro moth Phyllonorycter clemensella.
Consequently I was wondering if I would find a lot of mines at my study preserves this year. In fact, Phyllonorycter incidences were relatively high in both forests, in 15 percent of understory leaves at Maple Grove and 4 percent at Meacham. Statistically there were more at Maple than at Meacham, which has been true over the years, probably because of more intensive management at the latter site (controlled burning, and culling of maple saplings). Numbers were not different from last year at Maple Grove, but there was a statistically significant increase at Meacham for this species, possibly because there was no burn last year.
The other leaf miners were present in lower numbers that were indistinguishable from last year’s values. The two species of moths in genus Caloptilia, which leave their mines early and construct little cones or boxes in the leaf lobe tips for most of their development, were more abundant at Maple Grove (8 percent incidence) than at Meacham Grove (2 percent of leaves had them). While 3 percent of leaves at Maple Grove had blotch mines of Cameraria saccharella (another tiny moth), none of the 300 leaves in the Meacham Grove sample had any (only one had a mine last year). The fourth mine is distinctive in having a winding linear form.
This one was present in low numbers that statistically were indistinguishable between the preserves (8 leaves at Maple, 1 at Meacham). In November I’ll return to assess canopy incidence of these moths.