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Gold to crimson leaves are not the only signs of a changing season.

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A black and russet-banded Woolly Bear makes its way along Little Crum Creek.

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 Come spring, it may pupate, emerging as an adult Isabella Tiger Moth.

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But autumn’s caterpillar must first endure a long cold winter:
taking shelter, curling in bristly cover against predators,
and, incredibly, generating a cryoprotectant chemical
to safeguard cells from freezing temperatures…

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waiting for spring and the return of warmer weather.

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Sycamore tussock moth larvae are known to drop in on anyone who’s spent a bit of time beneath a sycamore tree in July.

These hungry caterpillars then venture to skeletonize several of the tree’s leaves before becoming sycamore tussock moths (Halysidota harrissi).

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That is, if they’re not devoured along the way.

Chances are, with her long, piercing ovipositor, a female braconid wasp could insert her eggs directly into a caterpillar.

The hatched wasp larvae will then feed on the caterpillar’s insides, break through its skin, and spin cocoons on the poor worm’s back.

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This one survived barely longer than the wasp pupation.

Below, you can just about see the neatly cut and lifted lids where the wasps emerged, leaving their spent cocoons and desiccated host behind.

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[Though they escaped observation, I inferred this general identification of braconid wasps based on a discussion at BugGuide.net.  You can read the discussion here.]

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100_5034cropIntroduced to Canada from Europe sometime around 1860, the cabbage white butterfly’s erratic-looking flutter enlivens all of North America from early spring through fall.100_4749edcrop

 

 

Along our creek, the brilliant, yellow-streaked and green caterpillar emerges from its egg to feed.

Soon, wrapped in protective casing called a chrysalis,  the caterpillar undergoes an extraordinary metamorphosis into a white butterfly.

Fully-formed females emerge with two black wing spots, and males with just one.

We’ll often see two cabbage whites engage atop a low plant, commencing a rising spiral chase through the air, perhaps a fast-fluttering courtship to renew this perennial metamorphosis.