Newly described flies...from our yard

In addition to dragonflies and damselflies, our other entomological interests have leaned toward Hymenoptera (bees and wasps, although not ants), flies, and moths. We've recorded over 750 species of moths on our property, and a fair number are leaf-mining moths. The interest in leaf-mining moths dates back to a paper I wrote in 2017, Native Birds Exploit Leaf-Mining Moth Larvae Using a New North American Host, Non-Native Lonicera maackii. 

After that interesting discovery, we began paying more attention to leaf mines. Not all mines are created by moths -- many are also flies, beetles, and sawflies. Identification requires a knowledge of plants -- since the insects are closely tied to particular host families -- and the help of Charley Eiseman and his monumental work, Leafminers of North America. 

We began rearing insects from mines we found on our Washtenaw County property. It was not uncommon to be unsuccessful in this endeavor: mines may have already been vacated; the larvae are parasitized by many species of wasps, so often only wasps emerged; we could be thwarted if only females emerged and identification relied on examination of male genitalia; or the larvae or pupae simply did not survive overwinter despite our efforts to maintain proper conditions (including a "beer fridge" theoretically dedicated to them). But we always took photos of the mines and notes on the host plants, mine architecture, frass patterns, phenology, etc. If we were successful, we would send the more interesting specimens to Charley. In addition to his own knowledge, he works with a network of scientists to identify these insects. 

Charley's most recent paper was published earlier this month:

EISEMAN, C. S., LONSDALE, O., FELDMAN, T. S., & VAN DER LINDEN, J.  2026. Thirty-three new species of Agromyzidae (Diptera) from the United States and Canada, with new host and distribution records for 154 additional species. Zootaxa 5745(1): 1-265. 

As the title indicates, it is exclusively about leaf-mining flies, discussing new rearing records and hosts, and describes some new species. We were excited to find that our specimens or rearing information were included in 5 of these accounts. The most interesting were two newly described species and one first North American record. These are summarized below, along with a few photos of the mines (the flies themselves are small, and rather non-descript).

NEW SPECIES: Phytomyza cicutiphaga Eiseman & Lonsdale sp.nov.

Leaf mines of paratypes of Phytomyza cicutiphaga
on water hemlock, Lodi Twp., Washtenaw Co., MI

This species is described from specimens collected in 1975-1976 from mines in Western Water Hemlock (Cicuta douglasii) in Alberta, Canada and specimens we reared from our property in 2019 from Eastern Water Hemlock (Cicuta maculata). 

There are no other specimens or localities listed in the paper, and our specimens are among the paratypes. 

The authors note that there are photographs of mines similar to that of P. cicutiphaga (which are different from the mines of the other water hemlock miner, P. cicutella) from several northern states and provinces, but state that examination of adult genitalia is required for positive identification.

Our specimens (n=6) are in the Canadian National Collection. 

NEW SPECIES: Liriomyza lobeliae Eiseman & Lonsdale sp.nov.

Leaf mines of Liriomyza lobeliae on 
Cardinalflower, Lodi Twp., Washtenaw
Co., MI

We have been finding mines on Lobelia leaves in our yard since 2019 on Cardinalflower (L. cardinalis), Great Blue Lobelia (L. siphilitica), and Indian Tobacco (L. inflata). We could see that the larvae in the mines were flies, but despite many attempts, we were unable to rear them to maturity. We did get some parasitic flies, photos, and notes.

Eiseman and Lonsdale described this new species from 6 specimens from L. cardinalis from the Chicago Botanic Garden. In addition to the photographs of mines from our yard (the only records from Michigan), other photographed mines included in the species description were from Minnesota, Ohio, Ontario, and North Carolina. The authors concluded that although all the Lobelia species are common in New England, for example, no mines have been reported in that region, leading them to believe this fly may have a limited distribution. We'll be trying to rear these again in 2026 so that additional specimens are available for study.

NEW FOR NORTH AMERICA: Phytomyza spinaciae Hendel

Pupa of Phytomyza spinaciae on the underside of 
a leaf of Cirsium discolor (the mine is on the
upperside of the leaf). Photos of mines alone
can't be assumed to belong to this fly without
evidence of this type of pupa. Lodi Twp., Washtenaw
Co., MI

Since 2017 we have found leaf mines in various thistle species, including native Swamp Thistle (C. muticum) and Pasture Thistle (C. discolor), as well as non-native Canada Thistle (C. arvense) and Bull Thistle (C. vulgare). I've reared flies from thistles from both the University of Michigan-Dearborn campus in Wayne County and from our property in Washtenaw County. 

Our 10 specimens, along with quite a few others from Michigan and other states, represent the first confirmed North America records for this European fly. The first reports of mines were from Wisconsin in 2014. In addition to thistles, these flies also use knapweeds (Centaurea) as hosts in North America, but might also use burdocks (Arctium), Carduus, or related species, so we're keeping our eyes peeled to obtain new host records.

Our specimens are in the Canadian National Collection. 

We can't emphasize enough how generous and helpful Charley and his work have been over the years. Every time we think we just don't have the bandwidth to pay attention to or try to rear more leafminers, Charley provides incentive and inspiration. We encourage you to visit his blog and Patreon page to get your own dose of motivation.