Tuesday, September 27, 2011

Autumn Insects

Autumn is harvest time, a busy time for wildlife, a time to hoard food or fatten up for the winter. Many insect species don't attain maturity until the fall, and must find a mate and breed in the limited time available to them before first hard frost.

Sad to say, time is running out for this beautiful Common Buckeye (Junonia coenia). According to my Peterson Field Guide to Eastern Butterflies this insect is a "migrant and temporary colonist north to ... s. Ontario". Although Common Buckeyes theoretically colonize this area and even a bit farther north, this is my first encounter with this butterfly and I've never seen one even in larval form or as roadkill. Nor will it be around much longer: this species cannot survive our winters, and new generations from warm southern climes will have to resettle the harsher northern limits of their range all over again next spring and summer.

An inspiring insect, and all those appealing colors and patterns on the wings call for a hand drawn sketch.

Several species of darners (Anax junius and Aeshna sp.) and meadowhawks (Sympetrum sp.) are well known late season fliers. A bit of a wanderer and thereby less often seen is the Black Saddlebags (Tramea lacerata). But it was somewhat surprising to find this female – a teneral – as late as September 26th.

Sometimes Black Saddlebags aren't around for a year or two. But there seems to have been a bumper crop this year, and I've already encountered two others: one on September 16th at the intersection of Louisa St. and the Eastern Ontario Trail, the other on September 19th near the intersection of Alexander St. and the Eastern Ontario Trail.

Always look twice at twigs, bird droppings and dead leaves ... or even living leaves, that green "leaf" could be a Texas Bush Katydid (Scudderia texensis).

A closeup shot of the katydid's ovipositor.

This Maple Spanworm Moth (Ennomos magnaria) is doing its best to masquerade as a dead yellow leaf ...

... while a caterpillar (as yet unidentified) imitates a dry, unpalatable twig.

When an insect advertises its presence with bold colors it's for a good reason! This odd looking "carpenter ant" was was on the run when I took its picture so the image quality is rather poor. Luckily I was unable to capture it to take a closeup shot of it sitting in my hand because it can sting – it's not a carpenter ant, it's a wasp called a Velvet Ant. Timulla sp., possibly grotei, and this one is a female; males velvet ants can fly but the females lack wings. I don't know what kind of a punch Timulla can pack, but it has relatives nicknamed "cow killers" ...

Learn more about the life cycle of Velvet Ants at Wikipedia: Mutillidae.

Easily mistaken for a yellowjacket, the chalcid wasp Leucospis affinis is a parasite of Megachilid bees. Note how this female carries her ovipositor over the top of her abdomen. Another distinguishing characteristic (unfortunately not very clear in the photos) are the enlarged spiny femora on the hind legs.

Friday, September 16, 2011

Mystery Solved (?)

Now and again on my travels I chance upon odd things that are baffling, such as this photo taken back in mid-June. What is this strange and weird orange nodule? A gall? A fungus? A cluster of insect eggs?

As often happens random chance played a role in the solution. I was Googling for information on nettles when I stumbled upon images of a nettle gall, Puccinia urticata ... not quite like my unknown blob, but pretty close. A bit more searching turned up a better possibility – Cluster Cup Rust Fungus (Puccinia caricina). These fungi have a complex life cycle that alternates between more than one host plant; this is the aecia or spore producing structure of the fungus.

But my mystery isn't quite solved: Puccinia caricina alternates between sedges of the genus Carex and species of Ribes, forming the "cluster cups" containing aeciospores on gooseberries and currants. My fungus was on dogwood, and as yet I haven't found rust fungi utilizing dogwood as host plants. But I'm sure the answer will turn up eventually, as there are more than 4000 species of rust fungi to choose from ...

This photo taken in early August also rates among my most unusual finds for this summer. Obviously these little things had been moving and consuming the surface of the oak leaf. What are they? A species of slime mold? Slugs? Insect larvae? Try searching the Internet; if you're stumped the answer may be found in The Forest Floor Fungi at the Frink Center.

Based on size, general appearance and range, I think this spider is a Humpbacked Orbweaver (Eustala anastera); there's more information on genus Eustala at BugGuide.Net. And what a well concealed spider this is. It looks almost like a part of the knot it's hunkered down in, and had I not almost blundered headlong into its web and traced the strands back to their origins, I would have passed it by.

But this arachnid comes in a wide assortment of colors and patterns and it seems that I have not a mystery, but a mis-identification. While browsing the Eustala images at BugGuide.Net the photo to the far right in the second row caught my eye – this spider bears more than a passing resemblance to the "Giant Lichen Orbweaver" photos I posted last year in What's for Lunch?.

The plant in the next photo was encountered growing in the woods bordering Rapids Road late in August. The distinctive triple-compound leaves and spherical blue fruits should have made it a cinch to identify, nevertheless it took some time to find a name (it's not easy to search for images using a text description).

This is a species of Blue Cohosh – but all I can say based on the information in the photo is that it belongs to the genus Caulophyllum. There are two species of Caulophyllum in southern Ontario, the Purple-flowered Blue Cohosh (Caulophyllum giganteum) and Green-flowered Blue Cohosh (Caulophyllum thalictroides), and it looks like I'll have to wait until this plant blooms next spring to find out which one it is ...

The following photos have been sitting in my "unidentified" folder since I first encountered this flower a couple of months ago along the Moira River shoreline. Actually a close relative of Common Yarrow, the flowers of Sneezewort (Achillea ptarmica) resemble the flowers of Pearly Everlasting, and due to this superficial similarity I went on a proverbial wild (and unsuccessful) goose chase when trying to identify this plant.

The leaves have finely serrated edges.

This is a good example of why it's helpful to understand a bit about the structure of flowers. What appear to be the ray florets of Pearly Everlasting are actually phyllaries, the ray florets of Sneezewort really are ray florets. The next picture, taken a few weeks later, illustrates the phyllaries of Sneezewort ... with some complimentary caterpillar poop ... it appears that some species of insect finds this plant to its taste.

Wednesday, September 14, 2011

Banded Argiope (Argiope trifasciata)

At close to 20 mm in length and prominently marked with black and yellow bands on a silvery white background ("trifasciata" means three banded), this beautiful spider seems to be less common than the closely related Black and Yellow Argiope (Argiope aurantia). The female in the following four images was encountered in a sunny, dry field about a kilometer west of town.

These photos of what is a probably a male Banded Argiope were taken about a month earlier. It's unfortunate that I haven't been able to obtain a picture of a male and female spider next to one another, because something that photos can't convey is scale. Sexual dimorphism among spiders can be extreme, and at a length somewhere between 5 to 10 mm this male would be dwarfed by the much more robust female.

Wednesday, September 7, 2011

An Assemblage of Autumn Asters

Much like the goldenrods, this is "Asters for Dummies" and I'm only going to give a brief account of the flowers at first glance in the field. There are plenty of good websites detailing the finer points of aster identification; even so, what you can learn from looking at pictures on the Internet is rather limited. Experience is the best teacher – get out in the meadows, forests and wetlands with a good book and a camera.

Flat-topped White Aster (Doellingeria umbellata)
Height: Tall, approximately 100 cm
Habitat: Open areas along the Eastern Ontario Trail
Photographed: early to late August, still flowering in early September

The flat-topped panicles and sparse ray florets of this aster are distinctive.

Large-leaved Aster (Eurybia macrophylla)
Height: Tall, 100 to 120 cm
Habitat: Woodlands along the Eastern Ontario Trail
Photographed: early to mid August, still flowering in early September

Note the large, heart-shaped, stalked lower leaves, and stalkless upper leaves slightly clasping the stem.

The stems supporting the flower heads and phyllaries are downy; furthermore, the phyllaries don't spread and are blunt and rounded rather than terminating in a sharp point.

Heart-leaved Aster (Symphyotrichum cordifolium)
Height: Tall, 100 to 120 cm
Habitat: Open woodlands, Sheffield Conservation Area
Photographed: late August

The heart-shaped basal leaves are deeply notched where they meet the stem (compare to Large-leaved Aster above), the upper stem leaves are stalked and winged.

Photos of the phyllaries – note how they terminate in a point and lack the hairs typical of the Large-leaved Aster.

The upper stem leaves with their winged stalks.

New England Aster (Symphyotrichum novae-angliae)
Height: Tall, 100 to 120 cm
Habitat: Moist open fields along the Eastern Ontario Trail
Photographed: mid to late August, still flowering in early September

This aster stands out from the crowd, with its dense clusters of large flower heads composed of numerous, purplish-blue ray florets surrounding yellow disk florets.

A view of the phyllaries.

Purple-stemmed Aster (Symphyotrichum puniceum)
Height: Can be very tall, from 100 cm up to 150 cm
Habitat: Moist areas bordering marshes along the Eastern Ontario Trail
Photographed: early September

This aster can be a tough call. The hairy, purplish stems aren't always hairy or purple, and the ray florets can vary from pale blue to nearly purple.

Panicled Aster (Symphyotrichum lanceolatum)
Height: Tall, roughly 100 cm
Habitat: Moist, relatively open areas along the Eastern Ontario Trail
Photographed: late August, still flowering in early September

Open panicled flower clusters, flower heads with more ray florets and generally smaller lance-shaped leaves distinguish this species from the Flat-topped White Aster. This aster can be variable in form, making it hard to identify.

Heath Aster (Symphyotrichum ericoides)
Height: A short plant, most were no higher than 50 cm
Habitat: High, dry sandy hillsides bordering the Eastern Ontario Trail
Photographed: early September

Note the dense clusters of small white flower heads, with small leaves (dead or absent on the lower stem during flowering). The upper leaves and phyllaries are tipped with spines.

Calico Aster (Symphyotrichum lateriflorum)
Height: A small aster, 100 cm or less
Habitat: Open forested areas near the Point
Photographed: early September

Luxuriant clusters of small two-tone flowers on the upper sides of the gracefully arching stems are characteristic of this species.

Rush Aster (Symphyotrichum boreale)
Height: Small, most specimens were only about 30 cm high
Habitat: East Hungerford Road, near the Stoco Fen
Photographed: early September

A delicate, gracile wildflower with long narrow leaves bearing few flowers. This aster is not uncommon but isn't often encountered as it likes to get its feet wet, inhabiting in nutrient poor bogs and fens.

Arrow-leaved Aster (Symphyotrichum urophyllum)
Height: Fairly tall, close to 100 cm
Habitat: Open areas along the Eastern Ontario Trail
Photographed: early September

The close, upward sweeping stems catch the eye and are according to the book for this species. However, this aster proved challenging in certain other respects, and I'm still not entirely happy with some of the particulars of my study.

This is a bit bothersome ... the involucres and phyllaries aren't quite as illustrated on reliable Internet resources. But then, this specimen as a whole has a relatively pale aspect – including the disk florets – which should theoretically turn purple with age, not the pale brown I'm seeing. I guess asters don't read our field guides ...

The hairless stem and shallowly toothed leaves with winged stalks are correct for this species. These leaves were located on the lower part of the stem (but there was no evidence of true basal leaves).

Top and underside views of a narrower leaf, situated higher on the stem.

For the most part the characteristics of this plant conform to those given for the Arrow-leaved Aster, but I'm going to re-visit it in the near future to see if there are any changes as it ages. Here are some links to other studies of the Arrow-leaved Aster ...

Ontario Wildflowers
Nature through the Lens
Robert W. Freckmann Herbarium (University of Wisconsin)