A butterfly

Mustard White Butterfly (Pieris oleracea)

I saw this butterfly yesterday while working in my garden spreading old hay around rhubarb and currant bushes. It had probably just emerged from its chrysalis earlier in the morning and was finishing up drying its wings. The butterfly is the Mustard White Butterfly (Pieris oleracea) a species native to North America and occurs in Canada from the Northwest Territories south to Alberta and then east to the Atlantic seaboard. In the US it can be found from North Dakota to Maine.

The green larva with a single white or pale yellow lateral line and small black spots feed on members of the mustard family (Brassicaceae), such as rock cress (Arabis spp., Boechera spp., and Draba spp.), cuckoo flower and bittercress (Cardamine spp.), and toothwort (Dentaria spp.). There are usually two or three generations a summer with the last generation overwintering as a chrysalis.

Adult Mustard White Butterflies come in a spring and summer forms. The one in the photo is the spring form. Summer forms have less dark shading on the wing upper surfaces and the lower surface veins are also less dark. Adults feed on nectar usually from mustard family plants.

Previously Mustard White Butterfly was considered to be in the species Pieris napi, a European species commonly called the Green-veined White. They are regarded as distinct enough to be classed as separate species although some authorities consider the North American P. oleracae to be a subspecies of P. napi (synonym Artogeia napi) calling it Pieris napi subsp. oleracea. P. oleracae differs from P. napi by having chalky white upper wings while P. napi has dark spots and dark margins on the upper wings. Another difference is the tolerance of P. napi for garlic mustard (Alliaria petiolata) which is toxic to the larvae of P. oleraceae and thus a serious concern for the species survival where this plant occurs in North America to which it is not native.

Taxonomy

Insecta (Insects)
Order Lepidoptera (Butterflies and Moths)
Superfamily Papilionoidea (Butterflies and Skippers)
Family Pieridae (Whites, Sulphurs, Yellows)
Subfamily Pierinae (Whites)
Tribe Pierini (Cabbage Whites, Checkered Whites, Albatrosses)
Genus/species: Pieris oleracea

SOURCES

Bowden, S. R. (1979). Subspecific Variation in Butterflies: Adaptation and Dissected Polymorphism in Pieris (Artogeia) (Pieridae). Journal of the Lepidopterists’ Society
33(2):77-111.

Heinen R., Gols R., and Harvey J. A. (2016). Black and Garlic Mustard Plants Are Highly Suitable for the Development of Two Native Pierid Butterflies. Environmental Entomology, Vol. 45 (3):671–676.

Mustard White (Pieris oleracea) (Harris, 1829) at the Canadian Biodiversity Information Facility website.

Pieris oleracea at the Wikipedia website.

Species Pieris oleracea – Mustard White – Hodges#4195.1 at the Bug Guide website.

A Few More Spring Flowers

Red maple flowers (Acer rubrum)

Staminate catkins of quaking aspen (Populus tremuloides) floating in a pond.

Tea-leaf willow pistillate flowers (Salix planifolia)

Prairie willow staminate flowers (Salix humilis)

More flowers on shrubs and trees from around here. Trees like red maple (Acer rubrum) and quaking aspen (Populus tremuloides) and shrubs such as tag alder (Alnus incana), hazel (Corylus spp.), and willow (Salix spp.) are the first flowers of spring appearing before the more familiar spring ephemeral wildflowers that grow in forests.

Soon there will be other flowers in bloom. Hepatica (Anemone americana), stalked sedge (Carex pedunculata), and wood rush (Luzula acuminata) will come into flower in the next few days. These low growing plants occupy spaces on the forest floor and today on one of my rambles I noticed that many already have unopened flower buds.

It was a dark and stormy night

And warm, too, at a sweltering 50° F, so I made plans to be up late looking for moths and caddisflies. I turned on the porch light, made a little cup of espresso, and waited awhile. When I went out I almost couldn’t believe what I saw: Ancylis albacostana. The broad white band on the forewings certainly seemed to point to that species. But there were some differences. First, the wings are not uniformly leaden gray. Instead, there is a very noticeable amount of red forming a narrow triangle above the white band and is separated from that by a narrow black line. Then, below the white band is a narrow ash gray band. The main part of the forewings are leaden-gray. Finally, near the beginning of the forewings are two raised bumps. When I compared this moth to available photos it seemed not match well at all. The description of Ancylis albacostana by Kearfott is also at odds with this moth’s appearance. In an earlier post (here) I stated I had found Ancylis albacostana but later retracted that (there) when it appeared the moth in question was actually Capis curvata.

Also attracted to the light last night were five individuals of the caddisfly Glyphopsyche irrorata and three of the moth Agonopterix argillacea. I’ll be up late again tonight to get more photos of this Ancylis and other moths.

SOURCES

Kearfott, William Dunham (1905). Descriptions of New Species of Tortricid Moths From North Carolina, With Notes. Proceedings of the United States National Museum, Vol. 28: 319-364. Description on page 360.

Species Ancylis albacostana – White-edged Ancylis Moth – Hodges#3387 at Bug Guide.

Spring Flowers

Red maple flower buds close to opening.

Tea-leaf willow catkin with a blush of red just a few days before blooming.

Tag alder staminate catkins ready to bloom and spread pollen. Smaller pistillate flowers are just above them.

Tag alder staminate catkins in bloom and turning golden in the afternoon sun. The white in the background is snow.

American hazel staminate catkins.

It is April and spring is should to be well underway with flowers in the woods, trees putting out leaves, bees flying about, and frogs calling from the woodland ponds. But here in northern Minnesota you wouldn’t know it with the cold weather, occasional snow, and bleak landscape with only the conifers for greenery. There is still snow in the woods where the trees are thick and block the sun. The ground remains frozen except in the sunniest of sites and so none of the forest wildflowers have come out of dormancy. Even so, trees and shrubs are beginning to awaken albeit about 30 days late. The earliest of these are tag alder (Alnus incana ssp. rugosa), American hazel (Corylus americana), beaked hazel (C. cornuta), and tea-leaf willow (Salix planifolia). Following closely is the quaking aspen (Populus tremuloides) but only some groves (clones really) are flowering. Red maple (Acer rubrum) flower buds are swelling and I expect they will be in full bloom in a week. So far none of these shrubs or trees have produced any leaves. That will come later when flowering is over and temperatures are warmer at night.

Trees that flower in the early spring are mostly wind-pollinated a good strategy since insects may still be in hibernation or slow to move about. Tea-leaf willow is an exception and produces abundant pollen and nectar which attracts small wasps, solitary bees, beetles, and flies. These insects pick up pollen from the staminate flowers and transfer it to the pistillate flowers. Tea-leaf willow plants are either staminate or pistillate so the insects need to go from one to the other in the right order to effect pollination. The flowers of tea-leaf willow are fragrant and so lure the insects to them. But if insects are scarce like they are this year tea-leaf willow can still pollinate some of its flowers by wind pollination. Red maple is insect pollinated and has thick nectar-secreting glands in its bright red flowers to attract bees and other nectar feeders of many kinds. For a few days there will be a red glow in the forest canopy while the red maple is bloom.

Rain is forecast for early next week but the chances for a good downpour are very low. This is not a desirable situation as the low humidity, dry grass, and constant winds make fires more likely. A couple of rainy days and nights would certainly reduce the chances of a fire. Sunny weather isn’t all it’s cracked up to be.

So far I have heard no frogs in the woodland ponds and am wondering where they are. In past years wood frogs have begun calling in mid-April even when there was a bit of ice on the ponds. There ought to be some by now with the warm weather. I hope this isn’t an indication of a problem.