Ten thousand pins

I was updating our database of Diptera holdings in the museum this week and thinking about the enormous range in numbers of specimens in some families (see my earlier post on “why so many specimens?”). The Lyman Collection is very well stocked with flies. Some families are represented by only 1 or 2 pinned individuals. Not surprisingly, these are the rare things, families that are represented by very few specimens in most major insect collections. I was struck more by the families that dominate our collection- those groups for which we have more than 10,000 specimens. As I scrolled down the list it was obvious  that there are different reasons why each of these families is in the “10,000 Club” and in most cases it is not because they are naturally the most abundant fly families in any particular ecosystem. If that were the case, we would have mostly chironomid midges, cecidomyiid gall midges, sciarid fungus gnats, tipulid crane flies, mosquitoes, phorid flies and a few other families. As we’ll see, that’s not necessarily so.

So, here is the Lyman Museum’s 10,000 Club – the fly families represented by at least 10,000 specimens in our collection, and why:

1. Chloropidae (grass flies, frit flies, eye gnats) (65,000 specimens databased, and a few thousand in the queue) – A great example of the fact that the most abundant taxa in insect collections are often those that researchers in the museum work on. I have been working on the taxonomy and ecology of Chloropidae since I arrived at McGill in 1995 so it’s no surprise that lots of specimens come back from the field with me (and with many students who have also worked on the family). Because chloropids are one of the more abundant families of higher flies in many terrestrial habitats, we also generate lots of material in the course of ecology or inventory projects. We have  extracted fantastic specimens of Chloropidae from samples sent by generous colleagues all over the world. Our collection is particularly rich in North American material, but we have several thousand specimens each from Central America and Australia, as well as a smattering from all other continents (although I’m always trying to boost the exotic collection . . .)

2. Dolichopodidae (22,025 databased, plus a few thousand in the queue) – Another focus of recent research, with my former PhD student Scott Brooks making a tremendous effort to build our collection of Nearctic Dolichopodidae during his time in the lab. We’ve also generated several thousand specimens of long-legged flies in the course of ecological work in peatlands and wetlands in southern Quebec. Our ongoing collecting in the arctic is yielding up large numbers of specimens as well.

3. Cecidomyiidae (24,785) – The difficult but fascinating little gall midges may be the most species-rich family of flies in North America, but most Diptera collectors who are not cecid specialists tend to avoid collecting large numbers of these flies. The size of our collection is mostly the result of the M.Sc. project of former student Duncan Selby who reared vast numbers of Cecidomyiidae from decaying deciduous logs in an old growth forest near Montreal. It was daunting to see the sheer numbers of adult gall midges pouring out of the logs into emergence cages, and even more daunting to imagine the amount of effort then required to sort and identify these tiny flies. Unlike most of our Diptera collection, cecids are best mounted on slides or preserved in fluid (they don’t do well when dried and pinned).

4. Agromyzidae (14,505 databased, many more in the queue) – Our Curator, Stéphanie Boucher, is a taxonomic specialist on the leaf-miner flies and has been collecting and publishing on the family since 2000. This is also a group that turns up regularly in our sampling in grassland habitats because of their association with a broad range of host plants in open habitats. We have recently discovered that even relatively small samples of agromyzids from alpine meadows in the Rocky Mountains, or from arctic or subarctic tundra can have very high species richness despite few specimens. Lots of agromyzids seem to be rare, or at least hard to find.

5. Phoridae (13,465 databased, at least another 5000-6000 sitting in drawers) – We’ve never had a phorid student in the lab, and we often omit these difficult flies in our ecological analyses (yes, a grave oversight, to be sure) but nevertheless, we collect, process and label large numbers of these ubiquitous and abundant flies in just about all of our sampling programs, from peatlands to forests to high arctic tundra. Most of our specimens are in the gigantic genus Megaselia, which explains our fear of delving into the sorting. Phorids are one group in which dominance in the collection = dominance in the field. These fascinating little flies are everywhere.

6. Ephydridae (12,825) – Although ephydrids are diverse and dominant in most terrestrial habitats, our recent work in peatlands and other wetlands has really boosted the representation of shore flies in the collection. One species, Scatella stagnalis, is one of the most abundant higher flies in disturbed and restored peatlands in eastern Quebec.

7. Muscidae (11,666 databased, at least 10,000 more in the sorting queue!) – Like the dolichopods or cecidomyiids, a lot of the recent growth in our muscid fly collection can be attributed to another of our star former PhD students – Jade Savage, who works on this family. On the other hand, the Muscidae were one of the fly families well-represented in the collection before our recent period of growth. This is because of the close association of some species with livestock and agriculture. Muscids are also one of the dominant families in most of the ecological studies we’ve done in recent years and they are astoundingly abundant in our recent Arctic samples from the Northern Biodiversity Program.

8. Tabanidae (11,277) – Prior to our recent focus on higher Diptera diversity, the Lyman Museum has had a sporadic focus in the past on biting flies with a number of research projects contributing large holdings from eastern North America, as well as a smattering of specimens from Africa and elsewhere. This biting fly focus is especially obvious in the deer flies and horse flies, although we are also pushing 10,000 in the mosquitoes. We also have specimens of half the world’s species of tsetse flies (Family Glossinidae) even though the actual number of specimens is small.

9. Sphaeroceridae (11,141) – The sphaerocerid flies are perhaps the higher Diptera equivalent of Phoridae – inconspicuously successful and surprisingly diverse in a huge range of habitats. Our recent research in temperate deciduous forests and peatlands has yielded large numbers of specimens and species, although I have to confess a soft spot for these often dull little flies. My PhD thesis was on the systematics of a widespread and diverse genus of sphaerocerids and ever since those days I find it hard to pass over  interesting specimens in the samples.

Honorable Mention: Anthomyiidae, Empididae, Tachinidae -These three families are knocking at the door of the 10,000 Club, primarily as a result of their dominance in subarctic and arctic tundra ecosystems. Our ongoing collecting with the Northern Biodiversity Program has generated several drawers of all three families, and the Empididae in particular are turning out to be enormously diverse and dominant in terrestrial food webs in the arctic.

Of course, the collection has far more than just flies, so what about the other orders? As with Diptera, our big holdings often reflect past research interests over our 100 year history. Here are the 10,000 Club members in the pinned collection from other orders:

Orthoptera: Gryllidae (11,094), Acrididae (82,856), Tetrigidae (11,367), Tettigoniidae (13,636);

Hemiptera: Miridae (51,018), Cicadellidae (24,239), Membracidae (10,000+);

Coleoptera: Carabidae (41,386), Staphylinidae (19,287), Scarabaeidae (sensu lato) (25,907), Chrysomelidae (20,670), Cerambycidae (14,232), Curculionidae (14,400);

Lepidoptera: Pyralidae (11,362), Tortricidae (12,137), Nymphalidae (13,991), Geometridae (17,968), Noctuidae (29,799);

Hymenoptera: Apidae (14,056), Ichneumonidae (44,703, not counting a lot of new arctic material).

All the above is interesting, and it’s the sort of question that people tend to ask about museums (“how many do you have?”) On the other hand, such numbers are largely meaningless in the big picture. It’s how we use these specimens in research that matters. And to make specimens truly valuable in research we have to take the sorting and identification well beyond the level of family, to species where possible, and then make the associated ecological and evolutionary data available and accessible. All those specimens are the raw material for unravelling great questions about biodiversity. That’s the real value in a big insect collection.

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About terry wheeler

professor, museum director, entomologist, ecologist, naturalist
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