Sunday, June 12, 2011
New to the HBG: The Living & the Dead Psilid
Another rainy Sunday and another attempt to boost my rate of posting: meet the New to the Home Bug Garden series. Unlike, or rather exactly like, my ‘weekly’ series (Sunday Sawfly, Wednesday Wildflower, Aculeata Agonistes, Bumbling with Bombus, Australian of the Week), New to the HBG will appear only when I have the time, energy, pictures, and story to post. The only real difference is that this series will not be aimed at any particular taxon or cultural view, but at organisms that have recently shown up, been identified, or finally correctly identified.
The first in this series is a mystery fly that first showed up on 6 June 2009. Well, my wife captured quite a nice picture of the fly on that date anyway. The funny looking head and way the wings bent over the abdomen seemed like they were distinctive enough that we should be able to learn its secret name. We were pretty sure it was an acalyptrate Diptera, but there are far too many flies, even acalypterate ones. Our searching of the web and pestering of Dipterists led to no higher level of knowledge. So, one rainy Sunday, the picture was assigned to the Miscellaneous Diptera folder.
And that is where it sat until one sunny afternoon last week when I noticed this strange-looking bent-wing fly perching on the leaves of the Juliet Cherry and Red Currant. And that is when I did what we should have done two years ago – if you want to know the name of an insect, you need to collect a specimen and key it out or find a specialist to do it for you (read the caveat in the sidebar: HBG Names & Claims). Specialists are few and far between, but there is an increasing treasure of entomological resources on the web. First and foremost if you live in North America and have a fly, is the Manual of Nearctic Diptera (MND) – an Agriculture and Agri-food Canada Entomological Monograph that is now freely available as a pdf download from the Entomological Society of Canada website (and as reasonably priced print-on-demand volumes here).
The MND is a tremendous achievement and one wishes that similar volumes were available for each insect order. However, it is highly technical and contains only brief overviews of each family, pictures mostly of bits and pieces, and dichotomous keys to the genus level. To use a dichotomous key, you have to make a series of choices correctly: one mistake and you are buggered. In the case of this fly, I was flummoxed and had to ask for help from our friend Jason. From the pictures, he suggested a likely family: Psilidae (not to be confused with Psyllidae a family of sucking bugs). I had skipped over this couplet in the key because the mystery fly didn’t look like other flies in the families that I knew of, e.g. the Carrot Rust Fly formerly Psila but now Chamaepsila rosae (Fabricius, 1794). Duh! With Jason’s help, the MND, and my dead fly on a pin, I was able to identify the genus: Chyliza Fallén.
With the genus known and BugGuide, I was able to make a guess at the species, but how would I know it wasn’t another species in the genus? Enter the specialist, Matthias Buck – he said. ‘well, you need to check Melander 1920’. Melander’s paper came out in Psyche, the journal of the Cambridge Entomological Club. A few years ago this is where I would have ground to a halt, because tracking down a paper almost 100 years old in an obscure British bug journal would have been more than the effort was worth. Fortunately, the publishers of Psyche have made this journal both Open Access – anyone with an internet connection can download the papers – and have gone to the trouble of scanning in their entire backlog from 1874 to the most recent issue.
So, finally we come to the end of our search, the secrete name: Chyliza leguminicola Melander, 1920. Not only did Melander describe this species, but he included what seems to be all that is known about its biology: “... L. P. Rockwood, who has swept this fly from the lupine, Lupinus polyphyllus Lindl., at Forest Grove, Ore., toward the end of April. He has also found puparia attached to the lower part cf this plant during July, from which adults emerged the following March ...”*. And what should be growing under the cherry and currants – lupines!
Since psilid flies seem to feed on plants as larvae, I suppose our C. legumnicola might count as a pest. But we long ago stopped planting lupines – they come up on their own and seem to be doing fine even with the fly and the far more annoying Giant Lupine Aphid Macrosiphon albifrons Essig, 1911. I think we will welcome our Bent-winged Lupine Fly to the Home Bug Garden and pin no more.
*Melander, AL (1920) Synopsis of the dipterous family Psilidae. Psyche 27 (5): 91-101.