Sumitrosis inaequalis (Weber, 1801)

Eiseman, Charles S., 2015, Notes on Leaf-Mining Chrysomelidae (Coleoptera) in New England, The Coleopterists Bulletin 69 (3), pp. 453-458 : 455-456

Sumitrosis inaequalis (Weber, 1801)

I noticed an interesting difference in the mines of this species on Symphyotrichum from those on its other asteraceous hosts. Normally, S. inaequalis produces simple blotch mines with frass in randomly dispersed strips. This was the case in mines from which I reared this species on Ambrosia artemisiifolia L., Eurybia divaricata (L.) G.L. Nesom, Solidago flexicaulis L., and Solidago patula Muhl. ex Willd. (all Asteraceae ), as well as in a presumed mine of this beetle on Ageratina altissima (L.) R.M. King and H. Rob. ( Asteraceae ). However, on Symphyotrichum cordifolium (L.) G.L. Nesom, the larva produces a broad track with the frass deposited along the margins ( Fig. 5 ). I reared adults from such mines in Vermont and Massachusetts and observed the beginnings of a similar mine on S. puniceum in Massachusetts. Klein (2014) photographed a mine of this type on Symphyotrichum novae-angliae (L.) G.L. Nesom in Wisconsin. Consistent differences in frass deposition habits among leafminers tend to indicate different species, and it would be of interest to compare DNA barcodes of S. inaequalis from Symphyotrichum with those of apparently conspecific beetles reared from other hosts.

In my experience, S. inaequalis normally pupates in the original mine, but the larva I collected on S. cordifolium in Washington, Massachusetts on 8 July abandoned its leaf and entered a fresh leaf of S. laeve that I offered to it. The larva continued to produce the same frass pattern, and the adult emerged from this leaf by 30 July. The abovementioned mine on S. puniceum appeared by 8 July in a leaf I collected in Granville, Massachusetts (42.098817° N, 72.886339° W) on 3 July to rear another leafminer. The larva later transferred to a leaf of S. cordifolium but did not survive.

Sumitrosis inaequalis has been associated with goldenrods previously, but the particular plant species noted above are new host records. I collected two mines from S. flexicaulis in South Burlington, Vermont (44.489128° N, 73.162358° W) on 29 June and one from S. patula in Sheffield, Massachusetts (42.101552° N, 73.387531° W) on 9 July. All three adults emerged in July, but I failed to record the exact dates.

Figures

Figs. 1–8. 1) Egg of Chalepus bicolor, lateral view); 2) Egg of Chalepus walshii, dorsal view; 3) Larva and leaf mine of Microrhopala xerene; 4) Abandoned mine of M. xerene, with pupal blister torn open; 5) Mine of Sumitrosis inaequalis in Symphyotrichum cordifolium; 6) Mine of Dibolia chelones, showing two frass types; 7) Mature larva of D. chelones; 8) Five young larvae of D. chelones in a single leaf.