Category: Species Profile

Categories
diptera Species Profile

Callopistromyia, the Peacock Flies

For this article I’d like to consider one of the most beautiful insects I’ve ever had the pleasure of observing: the Peacock Fly (Callopistromyia annulipes) and its relative, the only other member of its genus the Peahen Fly (Callopistromyia strigula)*. The main difference in appearance between these two species is in their wings: C. strigula contains much narrower wings than C. annulipes (Kameneva and Korneyev 2006).

*There is no common name for C. strigula, so I made one up. You might be surprised that there isn’t a common name, but consider that there are hundreds of thousands of species of Flies, and many of these are only known within specialist groups that study the differences between them. This is also the reason that there isn’t much information available for these Flies despite their beauty and conspicuousness.

Callopistromyia annulipes, the Peacock Fly. Note the wide wings and the position they are held in above the body.
Callopistromyia strigula, the Peahen Fly. Note the relatively narrow wings, and their position held out to the sides of the body.

C. annulipes is distributed across the United States and occurs in three provinces of Canada: British Columbia, Alberta, and Ontario, while C. strigula is found in Manitoba, Ontario and Saskatchewan as well as several States. Over the past several years, this species has spread into Europe as well, no doubt via human means (Pintilioaie and Manci 2020). 

In both species males and females display, contrasting with many fly species in which only the males display for the females to choose from among them. I don’t want to discuss sexual selection and mate choice here in any depth. Suffice to say that because both males and females perform displays there is likely mutual sexual selection going on in these species, meaning that traits are preferred and chosen by both sexes in this species, rather than a female-choice bias or male-choice bias.*

*of course, this only applies if the displays and accompanying appearances are sexually selected for, but there are other ideas for what forces are selecting these displays (see further below).

Video of Peacock Fly (Callopistromyia annulipes) displaying on a bridge railing on the Lynn Valley trail in Simcoe.

Little is known of these species’ biology other than that they display on conspicuous surfaces (more on this below), and there are records of the adults of C. annulipes feeding on the frass from wood-feeding beetle tunnels* (Steyskal 1979). Their puparia** have been found beneath the bark of various deciduous trees, so it’s presumed that their larvae feed on dead wood, or fungi within dead wood or something associated with dead wood. 

*Frass is a fancy way of saying “insect excrement and related material” usually used in connection with wood-boring insects… that ‘related material’ bit is key here since although a lot of what we call frass passes through an insect’s digestive system it can also be broken up bits moved behind a wood-boring beetle, so less insect “poop” and more insect “debris”.

**puparia refers to the hardened larval skin that encloses the pupal stage of derived Diptera… which probably doesn’t explain very much unless you know what those other terms mean. Basically, instead of nothing surrounding the pupa (the transformative stage of insects, between larva and adult), a huge branch of the Fly Family Tree (the Cyclorrapha) hardens their final larval stage skin into a protective case, sort of the fly version of a chrysalis.

As with many Diptera, their larvae are mysterious. After much searching, I managed to find a few pictures of Callopistromyia larvae online. I was amazed and contacted the person who recorded these organisms to obtain permission to share the relevant information and images.

The pictures depict larval and pupal C. strigula which were found feeding on the inner bark of a boxelder tree (Acer negundo) (van der Linden 2018). I can’t find any pictures or information pertaining to C. annulipes larvae, but presumably they have the same or similar feeding habits. 

Finally, the most attractive thing about these species are their displays. The reason I’m writing about these flies is because I noticed them, and the reason I noticed them is because they strutted about on the railings of bridges on the Lynn Valley Trail. The Peacock Fly (Callopistromyia annulipes) in particular raises its large wings so that they meet above its back presenting a very noticeable display. By contrast, C. strigula adults display their wings in a more horizontal fashion. Presumably, these displays are about attracting mates and because the displays are performed by both sexes, they are about mutual mate choice. In other words, males are displaying to attract the attention of females and females are displaying to attract the attention of males. An intriguing possibility is that these wing displays are about more than finding a mate… they could also be an example of predator mimicry.

Can you see the face of a Jumping Spider in the Peacock fly’s wing-pattern?

A fascinating paper with an excellent title* describes how other species of Ulidiidae (the family of Flies that includes Callopistromyia) have wing patterns and displays that mimic the appearance of Jumping Spiders (Salticidae) (Hill et. al. 2019). The reason? Jumping Spiders are visually hunting predators of basically any insect they can catch. The wing patterns are possibly exploiting the visual system of Jumping Spiders by causing the spiders to believe they are staring down another Jumping Spider and so to be cautious. I can’t help but be intrigued by this idea, and somewhat skeptical. Despite its appeal, there are some problems with the hypothesis. One problem that came to my mind is that Jumping Spiders will hunt other Jumping Spiders. So if the pattern is supposed to resemble a Jumping Spider and deter them from predating the fly, why would it? The paper acknowledges that there are still many unknowns, but the authors make a good case that at least some insects are manipulating salticid responses to prey with visually deterrent patterns. And they also note: “In a natural setting even a brief delay in the attack of a salticid could allow these flies to escape” (Hill et. al. 2019). As always in science, more studies are needed…

*The title, for those of you who don’t read through the References section, is “Do jumping spiders (Araneae: Salticidae) draw their own portraits?” The idea is that in avoiding hunting insects that resemble themselves, jumping spiders leave those ones alive to reproduce in like kind and so jumping spider resemblances are crafted by the natural selection of the jumping spiders themselves.

There is always more to learn, and always new organisms to explore in the world. I hope you enjoyed my dive into the beautiful flies of the genus Callopistromyia, the Peacock Flies. 

References:

Hill, David, A. P. C., Abhijith, and Burini, Joao. 2019. “Do jumping spiders (Araneae: Salticidae) draw their own portraits?” Peckhamia 179.1: 1-14. (full pdf available here: https://peckhamia.com/peckhamia/PECKHAMIA_179.1.pdf)

Kameneva, Elena and Korneyev, Valery. 2006. “Myennidini, a New Tribe of the Subfamily Otitinae (Diptera: Ulidiidae), with Discussion of the Suprageneric Classification of the Family”. Israel Journal of Entomology. Vol. 35-36, 2005/6: 497-586.

Pintilioaie A-M, Manci C-O (2020) First record of the peacock fly Callopistromyia annulipes (Diptera: Ulidiidae) in Romania. Travaux du Muséum National d’Histoire Naturelle “Grigore Antipa” 63(1): 87-91. https://doi.org/10.3897/travaux.63.e50920

Steyskal, George C. 1979. “Biological, Anatomical, and Distributional Notes on the Genus Callopistromyia Hendel (Diptera: Otitidae)”. Proceedings of the Entomological Society of Washington. 81(3): 450-455.

van der Linden, John. 2018. https://bugguide.net/node/view/1510354

For other blogposts focused on Flies (the vast insect Order Diptera), see:

–5. Robber Fly Hunting Queen Ant

–Flies: The Natural History and Diversity of Diptera, by Stephen A. Marshall

–Flies Falling to Fungi and Other Dipteran Observations

–Fuzzy Flies and Song Sparrows

–Eastern Band-winged Hover Fly

Categories
mammals Species Profile

Big Brown Bat

Big Brown Bat (Eptesicus fuscus). Photo by Sherri and Brock Fenton, used with permission.

Last year, I observed 2 bat species while on a night hike with the Norfolk Field Naturalists (for more about this hike, go here). The 2 bat species I observed were Eastern Red Bats and Big Brown Bats. I’d like to explore their biology and natural history, specifically within Ontario. This first post will be focused on the Big Brown Bat and another will focus on the Eastern Red Bat. I will be pulling most of my information from The Natural History of Canadian Mammals (2012), by Donna Naughton, unless otherwise indicated.

Big Brown Bats (Eptesicus fuscus):

Meaning Behind the Name: Eptesicus is from Greek which means “I fly” and “house” because Big Brown Bats like to roost in houses, and the species name fuscus is Latin for “dusk” (Etymologia 2005).

Biology and Natural History:

At 13 cm long and with a wingspan of up to 39 cm, this is Ontario’s second largest bat (the largest being the Hoary Bat (Lasiurus cinereus), and is fairly common in southern Ontario. Their global range extends all the way south to South America, and at the northern end there are scattered reports from Alaska. With such a wide range, there are differences in their habits across it. For example, Big Brown Bats in Ontario hibernate through the winter in “caves, mines, and deep rock crevices, as well as heated buildings” (Naughton 2012), but in more southern regions with plentiful insect food throughout the winter, they are active year-round. The list above of hibernation sites are specific permanent locations bats will find to spend the winter. During the day, however, Big Brown Bats will use a variety of roost locations, including tree hollows and beneath bark*.

*A curious note describes a surprising discovery of a male Big Brown Bat that had been roosting beneath loose bark in a Michigan wetland. While the author of the note was interacting with a data logger in the wetland, “a strip of bark about 1 m in length fell from one of the trees and crashed into the water about 3 m away from me. Mixed in with the bark fragments and covered with duckweed (Lemna sp.) was a half-submerged bat that I eventually identified as an adult male big brown bat.” (Kurta 1994). I was glad to read that the bat was “torpid but unharmed” and after warming up “the bat flew away” (Kurta 1994).

Big Brown Bats are generalist insectivores, consuming basically any insects they can catch. Their diet of hard-bodied insects wears down their large teeth but apparently worn teeth don’t affect their feeding habits. They feed at night, if conditions are favourable (such as not rainy, and sufficiently warm night temperatures). On cooler nights, some bats will undergo torpor (a sort of mini-hibernation state) to save energy and forgo foraging. When they are out hunting, Big Brown Bats use echolocation to find insect prey. Although we think of echolocation calls as strictly for feeding, they inevitably function as signals, sometimes unintentionally. It has been demonstrated that Big Brown Bats are attracted to the echolocation calls of another species of bat (the Little Brown Bat, Myotis lucifugus) and the other species is attracted to Big Brown Bat calls as well (Barclay 1982). This is likely because echolocating bats represent an area with foraging opportunities or food sources.

Big Brown Bat (Eptesicus fuscus). Photo by Sherri and Brock Fenton, used with permission.

Pups are born in June-July in Canada, and begin flying at 21 days or later. In Eastern North America, most Big Brown Bats give birth to twins, while single pups are most often born in Western regions. Although the pups’ wings are the same size as adults, their weight is much smaller, providing them with an advantage while learning to forage. After about a month, the young are able to hunt for themselves (ie. are no longer dependent on nursing from their mothers), but will stick with their mothers for their first few hunts. Some male Big Brown Bats have lived more than 20 years (the demand on females of pregnant foraging and nursing is high and reduces their maximum lifespan).

Big Brown Bats are fascinating, and I was happy to hear and observe them last year. Next up will be the Eastern Red Bat!

References:

Barclay, R. M. R. 1982. “Interindividual use of echolocation calls: eavesdropping by bats.” Behavioral Ecology and Sociobiology, 10: 271-275. cited in: Altringham, John and Fenton, M. Brock, 2003. “Sensory Ecology and Communication in the Chiroptera” in: Kunz, Thomas and Fenton, M. Brock (eds.). 2003. Bat Ecology. University of Chicago Press.

Etymologia: Eptesicus fuscus. Emerg Infect Dis [https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3367660/]. 2005, Dec [date cited: February 11, 2023]. http://dx.doi.org/10.3201/eid1112.ET1112

Kunz and Lumsden, 2003. “Ecology of Cavity and Foliage Roosting Bats” in: Kunz, Thomas and Fenton, M. Brock (eds.). 2003. Bat Ecology. University of Chicago Press.

Kurta, Allen. 1994. “Bark Roost of a Male Big Brown Bat Eptesicus fuscus.” Bat Research News. Volume 35: no. 2,3.

Naughton, Donna. 2012. The Natural History of Canadian Mammals. University of Toronto Press.

For other mammal-focused posts, see:

Flying Creatures of the Night

Moose (Alces alces) Family

Swimming Squirrels

Categories
Species Profile Top 20 Photos 2013-2020

5. Robber Fly Hunting Queen Ant

Subject: Underworld Robber Fly (Neoitamus orphne) and New York Carpenter Ant Queen (Camponotus novaeboracensis).

Location: Algonquin Provincial Park.

Date: July 2017.

For an Introduction to this series (my Top 20 Nature Photos of 2013-2020) go here.

The Story Behind the Shot: Every ant colony, each civilization in the soil, has to begin with a single type of individual: an ant queen*. Queens are special individuals, easily separated from the workers by their wings (at this preliminary stage) and their relatively large size. While camping in Algonquin during the summer of 2017, my campsite was in the path of dozens of queen carpenter ants. I watched as several different individuals wandered through the pine needles and discarded their wings. I had also been separately observing a large robber fly that had taken up residence on my camping table, using the surface to survey for potential prey. At some point the robber fly descended upon one of these ant queens and I was lucky enough to spot the unfortunate queen and its fortunate hunter.

*nature never lets me get away with generalizations… I would have liked to say, for the drama, that every colony begins with a single individual, but that isn’t true at all. There are many species of ants that create new colonies with multiple queens as a rule, and many times groups of workers accompany the queen (or queens). One of the most famous of these species is the Southern Fire Ant Solenopsis invicta, but dependent colony founding (that is, colonies that begin with a queen dependent on workers as opposed to independent colony founding) is widespread in ants. As in all things in the natural world, the picture becomes increasingly complicated, the more we know (Peeters and Molet 2010).

The Story Behind the Species:

Part 1: New York Carpenter Ant (Camponotus novaeboracensis):

The ant queens that I saw that day had emerged from a colony in what is termed a mating swarm. Multiple colonies in the area, triggered by the weather conditions must have swarmed at the same time, winged ants filling the air and meeting to mate. The males of these ants die soon after mating, but the queens will live for several years if they can establish a colony. The vast majority of ant queens will also die during this mating flight. Holldobler and Wilson (1990) describe this well: “It follows that the brief interval between leaving the home nest and settling into a newly constructed nest is a period of intense natural selection among queens, a dangerous odyssey that must be precisely timed and executed to succeed.” After mating, the ant queens descend to the earth and never leave it for the air again, removing their wings and absorbing the flight muscles within to provide the nutrients for their first batch of eggs. Camponotus novaeboracensis prefers nesting in dead standing trees or fallen logs or stumps, but they are occasionally found nesting under rocks or cow dung (Ellison et. al. 2012). Contrary to what you may think, carpenter ants (the genus Camponotus) don’t consume wood for food, instead carving into decayed wood in order to create a nesting site. One of their major sources of food is actually honeydew from Homoptera (true bugs such as leafhoppers, treehoppers and aphids), but they also collect sap and hunt insects and will scavenge on dead vertebrates as well (Hansen and Klotz 2005).

Foraging as an ant worker is dangerous, there are many other creatures foraging that would hunt down ant workers, and that’s ok for the colony because each worker is just one small part of a larger whole. Camponotus novaeboracensis colonies can contain almost 9000 workers (Hansen and Klotz 2005), but usually only a single egg-laying queen*. So workers can be lost, and the colony continues, but the queen is important so the colony can begin. If she is lost before she can find a nesting site, as in my observation here, there can be no colony of thousands.

*Akre et. al. 1994 report that C. novaeboracensis colonies rarely have more than one queen, but it does happen.

Part 2: Underworld Robber Fly (Neoitamus orphne):

Robber flies are incredible hunters, swooping out from perches on branches or twigs (or in this case, camping tables) to pounce upon insects and stab them with their powerful piercing mouths. There are over 7000 species of Robber Fly (members of the family Asilidae) worldwide (Marshall 2012). Neoitamus orphne has a specific name, orphne, which refers to a spirit of Greek mythology that lived with Hades in the Underworld, and is sometimes referred to by the name “Styx”. I love the idea of this fly being named after a spirit of the Underworld, as this robber fly must send many souls of insects to Hades on a frequent basis. The individual pictured is a female, which will use that long tubular abdomen to lay eggs inside flower heads or leaf sheaths. The larvae then hatch and drop to the ground, where they will hunt down soil-dwelling invertebrates presumably (Marshall 2012). I say “presumably” because I don’t think anyone knows for certain what this species of robber fly eats as larvae but robber fly larvae are predators and this genus has larvae that live on or in the ground so it makes sense.

My photo captures a battle between two mother insects, one which has the potential to generate a social colony of 9000 worker ants, another which lives a solitary life snatching prey out of the air.

References:

Akre, R. D., L. D. Hansen, and E. A. Myhre. 1994. Colony size and polygyny in carpenter ants (Hymenoptera: Formicidae) J. Kans. Entomol. Soc. 67: 1-9, cited in: Hansen, Laurel and Klotz, John. 2005. Carpenter Ants of the United States and Canada. Cornell University Press.

Ellison, Aaron, Gotell, Nicholas, Farnsworth, Elizabeth, and Alpert, Gary. A Field Guide to the Ants of New England. 2012. Yale University Press.

Hansen, Laurel and Klotz, John. 2005. Carpenter Ants of the United States and Canada. Cornell University Press.

Holldobler, Bert and Wilson, E. O. 1990. The Ants. Harvard University Press.

Marshall, Stephen. 2012. Flies: the Natural History and Diversity of Diptera. Firefly Books.

Peeters, Christian, and Molet, Mathieu. 2010. “Colonial Reproduction and Life Histories” in: Lach, Lori, Parr, Catherine L., and Abbott, Kirsti L.(eds.) 2010. Ant Ecology. Oxford University Press.

I hope you enjoyed my foray into the lives of these fascinating insects. My next post in the ongoing series of My Top Nature Photos is going to be about a sneaky little amphibian.

For Previous posts in this series, see:

  1. The Pale-Painted Sand Wasp (Bembix pallidipicta)
  2. Moose (Alces alces) Family
  3. Canada Jay (Perisoreus canadensis)
  4. Common Five-Lined Skink (Plestiodon fasciatus)
Categories
Species Profile

The Teal Tale Teale Told

Some ducks make very different sounds than the traditional Mallard quack. On a return trip to the Big Creek conservation trail in Long Point, March 2022, I was quite intrigued to hear squadrons of ducks uttering whistle-type calls as they scooted about on the water or took to the air. These were American Green-winged Teal (Anas carolinensis), the smallest species of dabbling duck in North America, approximately pigeon-sized (Baldassarre 2014).

To hear what these small ducks sound like, here is a link to an audio recording of Green-winged Teals whistling: https://macaulaylibrary.org/asset/86925491.

Apparently, it is the males that whistle while the females produce quacks (Baldassarre 2014). Green-winged Teals breed across the boreal and deciduous forests of North America, preferring wooded wetlands. Their nests are very difficult to find, concealed among tall grasses or shrubs. These ducks migrate early in the Spring to the northern breeding grounds, and it’s likely that the Teals I saw in March were using Long Point marshes as a stopping ground on their way north.

A pair of Green-winged Teals on ice at Long Point.

Teals use their bills (and the fine toothlike combs at the edges called lamellae) to filter tiny food items from shallow water such as seeds and invertebrates. Unsurprisingly because of their overall small size, it seems that Green-winged Teals are particularly good at feeding on very small food items, as opposed to Mallards, which are more generalist feeders (Baldassarre 2014).

Two fun stories about the word ‘Teal’ to finish off with. One is that, according to wikipedia teal is a word that originally meant “small dabbling duck” or something like that and was applied to several species of ducks before it was applied to the blue-green colour*, because of the bright “teal” markings on the wings (and heads of the males).

*I can’t find this mentioned in my books about ducks or anywhere well-sourced. I believe it to be true and fascinating but wikipedia is the main source I can find this fact on, so take that how you will.

The colour on their wings and heads really is quite beautiful.

My other anecdote about Teals I would like to share is about one of my favourite nature writers, Edwin Way Teale (it’s also the reason this post has a Dr. Seussian title). In his book, North with the Spring (Teale 1951), he tells of a time when his naturalist ways came under suspicion by the law. He and his friend had been out one winter day, watching ducks at a pond. Across the pond was a building which used to be a military plant, and I guess the fear of foreign spies caused a local to report the pair of men staring in that direction with binoculars.

As Teale himself says: “The dialogue that ensued when the first officer reached us might well have been a skit on a vaudeville stage.

“What are you doing?”

“Looking at ducks.”

“What’s your name?”

“Teale.”

By the light in his eye I could tell he had heard about teal ducks. The light said: A wise guy, eh?

I have friends who are named Crow, Crane, Raven and Rook. Fortunately, they were not along that day.” (Teale 1951, p. 288).

In case you forgot that Green-winged Teals are small… here are some swimming near a Canada Goose for comparison.

References:

Baldassarre, Guy. 2014. Ducks, Geese and Swans of North America, 2 Vols. Johns Hopkins University Press.

Teale, Edwin Way. 1951. North with the Spring. Dodd, Mead, & Company.

For other posts about Long Point Observations, see:

–Bullfrogs and Buffleheads

–A Visit to Big Creek, Part 1

–A Visit to Big Creek, Part 2

Categories
Nature Observations Species Profile

A Green Heron Stalks the Shallows

Over the past few years I have come to appreciate how beautiful and wonderful birds are. Along with that appreciation has been the realization that there are diverse birds within a short walk or drive of my home. I have encountered new species of birds almost every time I go out to my new favourite birding destination: Long Point. Globally renowned for being a biodiversity hotspot, and a corridor for migrating birds crossing the Great Lakes, Long Point is full of a variety of freshwater habitats and a corresponding diversity of bird species. 

My most recent exciting encounter was with a species I had never before seen up close. Before this past year “Heron” meant the Great Blue Heron (Ardea herodias) the only species of heron I saw regularly, certainly the most conspicuous heron species across North America. But as I was wandering down a trail amid mudflats and shallow coastal marsh, I was treated to an incredible sighting: the small agile form of a Green Heron (Butorides virescens). Stalking swiftly through the shallow water, the Green Heron snapped at the water surface with fair frequency and was always on the move while it foraged. I wasn’t sure exactly what it was eating, but it certainly wasn’t fish unless it was catching tiny individuals. My guess is that it was feeding on aquatic invertebrates such as dragonfly larvae, or other water-dwelling insects. I couldn’t believe my luck to see this beautiful little hunter foraging within a few metres of me. 

Green herons breed across the eastern United States and Southeastern Canada (including Southern Ontario). The birds start arriving in Ontario at the end of April and are gone by the end of October (Davis and Kushlan 2020). Green herons spend the winter in Mexico, Central America and Northern South America. Throughout their range they utilize essentially any fresh or salt-water habitat from inland marshes to coastal mangrove forests (Davis and Kushlan 2020). With such a diversity of habitats, they feed on a wide range of prey depending on where they are hunting including fish, frogs (and tadpoles), lizards and snakes, rodents, crayfish and crabs, aquatic and flying insects, spiders, snails, earthworms and leeches (Davis and Kushlan 2020). Besides these aquatic organisms, they even feed on such surprising prey as nestling birds (Wiley 2001). Clearly Green Herons are opportunistic foragers using a variety of feeding methods to capture such diverse prey. One of the most fascinating foraging behaviours is bait-fishing. Several birds are known to do this*, but Green Herons are the heron most frequently observed using this strategy to catch prey. In one of the first reported instances of bait-fishing in the Green Heron (Lovell 1958) the bird used bread thrown by people to attract fish to the surface and even chased American Coots (Fulica americana) away from its bait.   

*Many herons have been reported to use bait such as the Black-crowned Night Heron (Nycticorax nycticorax), the Great Blue Heron (Ardea herodias) and the Great Egret (Ardea alba), but other birds are also reported bait-fishers, such as the Pied Kingfisher (Ceryle rudis) and the Black Kite (Milvus migrans). Check out this article for more fascinating details: Davis and Zickefoose 1998 (Bait-fishing by Birds: A Fascinating Example of Tool Use | Searchable Ornithological Research Archive (unm.edu))

This photo of the Green Heron shows it off in a more “typical” Heron pose, demonstrating how long its neck is.

The individual that I watched wading through the shallows was not using any bait-fishing techniques, but rather seemed to be doing the more commonly observed stalk-and-stab technique of herons the world over. After roaming across the patch of water directly across from me, it took to the air and flew a short distance to begin combing a new area of wetland for food. What a beautiful, amazing bird.

References:

Davis Jr., W. E. and J. A. Kushlan (2020). Green Heron (Butorides virescens), version 1.0. In Birds of the World (A. F. Poole and F. B. Gill, Editors). Cornell Lab of Ornithology, Ithaca, NY, USA. https://doi.org/10.2173/bow.grnher.01

Wiley, James. 2001. Green Heron (Butorides virescens) predation at Village Weaver (Ploceus cucullatus) nests. Journal of Society of Caribbean Ornithology Vol 14 No. 3 pp 130-133. (https://jco.birdscaribbean.org/index.php/jco/article/view/571/475)

Lovell, Harvey B. 1958. Baiting of Fish by a Green Heron. The Wilson Bulletin Vol. 70, No. 3 (Sep., 1958), pp. 280-281 

Davis, William E. and Zickefoose, Julie., 1998. Bait-Fishing by Birds: A Fascinating Example of Tool Use. Bird Observer Vol. 26 No. 3, pp 139-143.

For previous posts focused on birds or Long Point, see:

–Return of the Ravens

–Canada Jay (Perisoreus canadensis)

–The Wonders of Wrens

–A Visit to Big Creek, Part 1 and Part 2

–Pinery Birds, Winter 2019

Categories
Species Profile

Introduced Pine Sawfly

Diprion similis

Diprion similis larva at Algonquin Provincial Park, September 2019.

Sawflies are a group of insects that many people haven’t even heard of. Part of the reason is because, in appearance and behaviour, they are like a hybrid between two major groups: their larval stages look like caterpillars (larvae of Butterflies and Moths ie. Lepidoptera), and their adult stages look like bees or wasps (Order Hymenoptera). Despite appearances and lifestyle, it is the latter category that they actually fall under: Hymenoptera which also includes the Bees, Wasps, and Ants. The major features that set sawflies apart from their relatives is that they eat plants, and they don’t have the constricted “wasp waist”. You might find this a little confusing, as Bees certainly don’t have an obviously thin waist, but they actually do have a constriction between their thorax and abdomen, it’s just more difficult to see than in many wasp species.

Like many insect Orders, the name Hymenoptera refers to a distinct aspect of the members’ wings (‘ptera’ is derived from the Greek for wing). Hymenoptera doesn’t have an easy translation though, like say Diptera for the True Flies (di = two, ptera = wings). The beginning part of the word is either from the word “hymen” which means membranous, or from the word “hymeno” which refers to the Greek God of Marriage. Hymenopteran wings are membranous, but they also have tiny hooks that link their fore- and hind-wings, meaning that they could be said to be “married” wings as well (Grissell, 2010). Whatever the case, the group is one that includes thousands of species of wasps, bees, ants, and of course, sawflies.

The common name “sawfly” is describing the way the female sawfly lays her eggs. Instead of a stinger or stinger-like ovipositor (egg-layer) at the end of her abdomen (like most of the other Hymenopterans), the female sawfly has a saw-like ovipositor, a cutting tool that she uses to open up plant tissue, and then inserts her eggs within.

This is what the Introduced Pine Sawfly (Diprion similis) does to pine needles. D. similis prefers White Pine (Pinus strobus) as its host plant (in North America), but will lay eggs and successfully grow to maturity on several other pine species. The female lays about 10 tiny eggs inside a pine needle (Cranshaw, 2004). After inserting the eggs, the female seals them in with a secretion that hardens for protection (Wagner and Raffa, 1993). The larvae that hatch from the eggs begin to feed on the pine needles. For the first part of their life, they will remain together but begin to disperse as they grow older. These larvae prefer to feed on needles that are at least 1 year old, probably because the younger needles are full of more toxins (Wagner and Raffa, 1993). As they consume needles, they grow, from 2.5 mm long upon first hatching to almost 3 cm before the larva is said to be “mature”. They don’t grow continuously, but rather have to molt and enter a new size class each time they’ve gained enough nutrients. For female larvae, they have six growth stages between molts and the males have five (CABI, 2020).

During this time, you would be forgiven for thinking they were caterpillars, because they look very similar. The way to tell caterpillars from sawflies is to count the number of legs. Their first set of legs will be six, and jointed for both groups, but they will also have a number of legs behind these called “prolegs”. If the larva you’re looking at has more than 5 pairs of prolegs, it’s a sawfly. Another giveaway is the distinct single eyes of sawfly larvae, as opposed to tiny ocelli (miniature eyes in clusters) in caterpillars.

  • A Macremphytus sawfly larva. The head is to the right, behind it is the first three pairs of true legs, then behind those are a series of lumps that denote the pairs of prolegs, which number at least 8 (so more than 5).
  • A Monarch caterpillar (Danaus plexippus) whose head is facing down and to the left. The pairs of true legs are just behind the head. The lumpier prolegs are further back (up in the picture), and number only 5.
The difference between Sawfly larvae and Butterfly (or moth) larvae.

Once they’ve reached their final larval stage, they spin a cocoon around themselves with silk, and transform within. Diprion similis larvae prefer to form their cocoons in the pine trees where they feed, rather than on the ground like many other sawflies.

In Europe and most of North America there are two generations per year, which means that what happens next depends on what time of the year it is. If the larvae have grown enough and created their cocoons in the summer, they will develop within in about 2 weeks into adults, but if they have reached this point near the end of fall, they will enter diapause (essentially insect hibernation) for several weeks before emerging in the spring (CABI, 2020). When they emerge, the adult sawflies are entirely different creatures, just as butterflies and moths are very distinct from their caterpillar young. The adults have wings, and with these they search for mates.

Adult Male D. similis, displaying the feathery antennae used to track down a female (Photo credit: Scott R. Gilmore.)

Males are attracted to females by pheromones (a chemical signal between members of the same species), as one would guess by the male’s elaborate antennae. The males can be attracted to a female across 61 m of open field, which is a great distance for an insect only a matter of centimeters long (Wagner and Raffa, 1993). Once mated, the female lays eggs in pine needles, and we are back at the beginning of their life history.

One note about mating: it isn’t necessary for the female to mate to be able to lay eggs. She shares with the other Hymenoptera a bizarre (to us) chromosome setup known as haplodiploidy. Females have one set of chromosomes (the mother’s) and males have two (mother and father). What this means in practice is that a female sawfly can lay an egg that will develop into a fully functional male offspring without ever going through the trouble of mating. This has implications for the spread of such organisms, as not all members of the population need to pair up to contribute to the next generation.

Which brings me to my final discussion of this species: they are commonly referred to as the Introduced Pine Sawfly because they were accidentally introduced into North America from Europe, likely in plant nursery stock imported in 1914. They have become well established in North America since then. Thankfully, they only very rarely reach a high enough population density to be considered an “outbreak” invasive species, and though they feed on tree leaves (needles), many predators and parasitoids feed on them (Wagner and Raffa, 1993).

The last time we were camping at Algonquin Provincial Park, I encountered quite a few of their larvae likely because they were in the fairly mobile phase before finding a spot to spin a cocoon (it was the end of September, the beginning of October). They may be an introduced species, and they may feed on White Pines, defoliating some of the branches, but as with any organism, they have a story all their own, and I think it’s worth telling.

Diprion similis larva hanging onto the end of a pine needle in Algonquin Provincial Park.

References:

Wagner, Michael R. and Raffa, Kenneth F. Sawfly Life History Adaptations to Woody Plants, 1993.

Cranshaw, Whitney. Garden Insects of North America. 2004.

Marshall, Stephen. Insects: Their Natural History and Diversity. 2006.

Grissell, Eric. Bees, Wasps, and Ants. 2010.

CABI, 2020. Diprion similis. In: Invasive Species Compendium. Wallingford, UK: CAB International. www.cabi.org/isc.

Categories
Species Profile

Eastern Band-winged Hover Fly

Ocyptamus fascipennis

Ocyptamus fascipennis adult, spotted at Algonquin Provincial Park, August 2019

When you’re interested in insects, you’re always going to be running into something new. There is always one more creature that you have never seen before, one more behaviour you haven’t heard of, and that’s because insects are incredibly diverse. Today, I’m going to pick out just one of the many species of insects to zoom in on, and explore its story.

The species I’ve chosen is Ocyptamus fascipennis, or the Eastern Band-winged Hover fly. Let’s start from the top: Ocyptamus fascipennis is a “True Fly”, a member of the Order Diptera, which is a division of the Class Insecta. Diptera means “two wings” which gives you the easiest way to identify this group of insects when you encounter them. Almost all insect groups have 4 wings (two pairs) but these pairs of wings have been modified into very different structures in different lineages of insects. For the True Flies, one pair of wings still provides lift and flight, while the other has been reduced into tiny knobs known as halters. These reduced wings act as stabilizers, giving the flies the ability to perform aerobatic feats of agility (as I’m sure we’re all familiar with in House Flies (Musca domestica)). The halters of Diptera are more than just balancing beams, they’re actually sending complicated signals to the fly about its aerial position.

Ocyptamus fascipennis is part of a Family of True Flies called Hover Flies, or Flower Flies (Family Syrphidae). The Syrphids are common insects in gardens where they feed on nectar and pollinate flowers. Because of this habit, many species of Syrphids have taken on the appearance of more conspicuous flower visitors such as bees and wasps, in order to gain some protection from the classic warning colours of black-and-yellow stripes. O. fascipennis in particular seems to mimic solitary wasps or types of parasitoid wasps with its elongated and narrow abdomen.

So far, we’ve been talking about adults of these flies, but all insects go through multiple life stages, some more dramatically varied than others. Diptera undergo holometabolous growth which is a fancy way of saying that they have life stages that look very different from each other and one of those stages is a transformation phase which is mostly immobile. When young hoverflies (larvae) hatch from eggs, they look very different from the adults landing and lifting from flower petals in gardens. Larval O. fascipennis have no wings, and no legs, and are sometimes known by the name that many fly larvae receive: maggots. O. fascipennis larvae don’t consume garbage or dead animals, but instead are active predators, squirming across leaves in search of their prey: aphids.

Stephen Marshall, in his incredible book about Insects describes Syrphine larvae hunting as this: “at night they move blindly among the aphids, grasping victims using typical maggot mouth hooks, then holding the doomed aphids up off the surface to consume the body contents.” (Marshall, 2006).

A Syrphine larva hunting a herd of aphids (photo credit: Christine Hanrahan)

It seems then that Flower Flies are very beneficial insects to have in the garden. They provide pollination for flowers, and their larvae consume plant-eaters such as aphids and related scale insects.

While I was unable to find very much information pertaining to Ocyptamus fascipennis specifically, one other member of the genus deserves special mention because of its interesting larval habitat: tank plants (Bromeliaceae). The Central American and South American species of Ocyptamus that inhabit these confined aquatic habitats (pools of water within the plant itself) ambush and consume other aquatic insect larvae that live in the plants alongside them. The larvae are even thought to use a paralyzing venom to subdue their prey (Rotheray et al, 2000).

All in all, Ocyptamus fascipennis and its relatives are fascinating flower flies with intriguing habits. I hope you’ve enjoyed taking a closer look at them today.

UPDATE NOVEMBER 2021: Near Point Pelee, Ontario, individuals of Ocyptamus fascipennis were observed apparently migrating. The flies were observed moving East to West along with several other insects including tens of thousands of potter wasps (Ancistrocerus adiabatus) (Skevington and Buck 2021). The authors of the paper note that insect migration is a largely understudied phenomenon, especially in North America, so further study is needed to figure out the details.

References:

Rotheray, G. E., M. Zumbado, E. G. Hancock and F. C. Thompson. 2000. “Remarkable aquatic predators in the genus Ocyptamus (Diptera, Syrphidae).” Studia Dipterolologica 7: 385-98. (full text available here: https://repository.si.edu/bitstream/handle/10088/17095/ent_FCT_89.pdf?sequence=1&isAllowed=y )

Marshall, Stephen. Insects: Their Natural History and Diversity. 2006.

Marshall, Stephen. Flies: The Natural History and Diversity of Diptera. 2010.

Skevington, Jeffrey H., and Buck, Matthias. 2021. “The first documented migration of a potter wasp, Ancistrocerus adiabatus (Hymenoptera: Vespidae: Eumeninae)”. Canadian Field-Naturalist 135 (2): 117-119.