Thursday, November 15, 2012

Milkweed's last hooray

Striped garden caterpillar, Trichordestra legitima

It is November. We are deep into autumn. Monarch butterflies stopped feeding on milkweeds and are long gone from this area. Milkweeds are wilting, dropping leaves, some covered with sooty mold, and others reduced to dry stems and seed pods. Still they continue to nourish and shelter a number of species that depend on them.

A noctuid moth, the striped garden caterpillar moth (Trichordestra legitima), spends the winter as a pupa. An occasional caterpillar hangs around this late in the season taking advantage of the last scraps of food. Unlike monarchs, it is not choosy. This one happens to be feeding on common milkweed but others find nourishment in an incredible assortment of plants, from asparagus to yarrow or tobacco.

Oleander aphid, Aphis nerii

Aphids are busy sucking juices from the few remaining green stems and leaves of milkweeds. Their colonies are usually considerably larger this time of the year. The most frequent species on common milkweed is the oleander aphid (Aphis nerii), a bright yellow-orange one.

Myzocallis asclepiadis
Less common is the aphid called only by its scientific name, Myzocallis asclepiadis, about the same size as the oleander aphid, almost translucent, with dark dots and often seen sharing plants with its more colorful relative. Myzocallis asclepiadis specializes on Asclepias, as its name suggests. The oleander aphid has broader tastes, living on other members of the dogbane family (Apocinaceae), as well as occasionally some plants of the potato family. This aphid is not native to this hemisphere, and, curiously, there are no males in the North American populations, so they only reproduce parthenogenetically or by virgin birth.

Labidomera clivicollis, larva
Labidomera clivicollis
 A colorful beetle, the swamp milkweed leaf beetle (Labidomera clivicollis) is not as selective as its name indicates and also feeds on common milkweed, as this larva was doing. It is unusual to find a larva still feeding in November. There was an adult nearby.

large milkweed bug, Oncopeltus fasciatus
A common denizen of dry and dying milkweeds is the large milkweed bug (Oncopeltus fasciatus). Both adults and juveniles (called nymphs) feed on seeds of this plant as well as leaves. So it is not surprising to see them in large numbers in November.
Soon all these milkweed visitors will be gone, too. The one that will remain will be the longhorned milkweed beetle (Tetraopes tetrophthalmus). Its larvae will remain buried underground feeding on roots and waiting for next spring.

Beginners Guide to Pollinators and Other Flower Visitors

© Beatriz Moisset. 2012

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