Me, Litterbug

by Carl Strang

Last week, Nikki Dahlin and I found a black plastic bag blown up against the base of a tree at Mayslake Forest Preserve. We were going to throw it away, but Nikki noticed something.

A polyphemus moth caterpillar had pupated against the bag. Normally its secretions would simply cement its wraparound dead leaf, but here the bag was attached as well.

A polyphemus moth caterpillar had pupated against the bag. Normally its secretions would simply cement its wraparound dead leaf, but here the bag was attached as well.

A dilemma. I decided to compromise, cutting away and properly disposing of the bulk of the bag, but returning the bit of plastic with the cocoon to the ground, as shown in the photo. Technically that makes me a litterbug, but I intend to return periodically to check, and will remove the plastic when the moth is out.

Can’t help but wonder how far that bag with its dormant passenger was blown through the air before landing at Mayslake, a preview of the moth’s flying days to come.

Small Mysteries

by Carl Strang

Even when distracted the mind notices, finds questions.

Some remain intractable. Why has Culver, Indiana, become turkey vulture central?

Vultures roosting at the Culver town park on a morning last week.

Vultures roosting at the Culver town park on a morning last week.

There have been times in the past decade when 30 or more vultures circled above that part of the town.

Other mysteries are more easily resolved. Back at Mayslake Forest Preserve this week, I noticed a polyphemus moth cocoon on a small tree.

The oval shape, pale color, and loose attachment to a twig are distinctive.

The oval shape, pale color, and loose attachment to a twig are distinctive.

There has been no sign of this large species on the preserve in the years I have been there. But this tree was planted just last year, and checking my notes I found that it was installed in November. Obviously the cocoon had formed in the nursery.

On another day I was startled to see a red cedar decked out in structures like Christmas tree ornaments.

These are the spore-producing structures of the cedar-apple rust, which cycles between the cedars and apples or crab trees, and can impair both host species.

These are the spore-producing structures of the cedar-apple rust, which cycles between the cedars and apples or crab trees, and can impair both host species.

It seems the cool, wet weather promoted the rust’s development on that tree.

A questioning attitude becomes reflexive when one practices inquiry and spends time out-of-doors.

Straight-lanced Meadow Katydid

by Carl Strang

Yesterday I described sweep sampling. The day after I tried out the technique in the stream corridor prairie, I shifted to Mayslake’s savannas. The first sample, taken in the tall herbaceous vegetation at the edge of the north savanna, produced this female meadow katydid.

The critical feature, as I understand it, is the length of the ovipositor, the sword-like extension at the tip of the abdomen. On this individual the ovipositor is longer than the femur, and so I conclude that it is a straight-lanced meadow katydid. This was the first species on the list of those I had not yet found, as it is said to be very common. The song is a faint, high-pitched, continuous trill, which fates it to blend with all the other insect songs even with the aid of the SongFinder. The short-winged and slender meadow katydid songs are easier to pick out because the trills are relatively short and preceded by ticks. The spaces, starts and stops allow those songs to stand out. Other features that may distinguish it from those other two small meadow katydids are the short wings (compared to the slender meadow katydid’s very long ones) and the green abdomen tip (that of the short-winged meadow katydid is yellow).

Among the other insects that turned up in the savanna sweep samples was this little caterpillar, which may be an early instar of the polyphemus moth.

I will continue to seek out the more obscure singing insects.

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