Egg of little brown skipper

[rjlittlefield]

Today the little brown skippers are flying around my lawn laying their last batch of eggs before winter. I followed one around to get this subject.

Skipper eggs are much different from the highly sculptured butterfly eggs that we usually see in the forums. Their shape is just a smooth rounded cone, with a very subtle surface texture that is reminiscent of "crinkle coat" paint.

Here is the entire egg, attached to the bit of dry grass that mommy skipper glued it to. 4X NA 0.10 objective, focus stacked at 50 µm, cropped. The irregularity at upper right of the egg almost looks like a "transparent foreground" stacking artifact, but it's not. The egg really does have a hard irregular profile at that spot. I have no idea why; I suspect it's an individual defect but I don't even know that for sure.



A closer view, 20X NA 0.40, focus stacked at 5 µm, cropped.



Here's what the egg looked like in situ, after being returned to the lawn. The fibrous plate at upper left is a small piece of masking tape that I used to hold the bit of dry grass to a microscope slide for the earlier pictures. Shot at 1:1 with a macro lens, slightly cropped.


It was surprisingly difficult to get good lighting for the microscope shots. What I ended up with was a single fiber bundle with a Kleenex tissue wrapped tightly around its tip, making a slightly diffused light source of 6 mm diameter, positioned 20 mm away from subject.

Hope you find this interesting!

--Rik

[NikonUser]

It would be nice to know the species name, an image of mommy may help.

You wrote: "Skipper eggs are much different from the highly sculptured butterfly eggs that we usually see in the forums. Their shape is just a smooth rounded cone, with a very subtle surface texture that is reminiscent of "crinkle coat" paint."

Far too generalized, may apply to your yard species but may not apply to other skippers.

Dingy Skipper egg - Photo: Reg Fry. All the skippers have highly sculpted roundish eggs.
SEE HERE

[rjlittlefield]

It would be nice to know the species name, an image of mommy may help.
...
Far too generalized, may apply to your yard species but may not apply to other skippers.

Good points, both. If they're flying again today, I'll try to get images of both some mommy and an egg that she lays. I suspect Hesperia juba, based on visual memory and on illustrations & text in Butterflies of Cascadia. But I would not be willing to place even a small bet on that ID.

Thanks for the link to the egg of Dingy Skipper. In my highly unscientific sampling over the years, I've only encountered skipper eggs like shown here. It's nice to know there's more variety.

The gallery of butterfly eggs that you pointed to shows both sculpted and smooth skipper eggs. They are accompanied by oddly inconsistent captions.
"Dingy Skipper egg - Photo: Reg Fry. All the skippers have highly sculpted roundish eggs. "
"Silverspotted Skipper egg - Photo: Reg Fry. Smooth, hemispherical eggs..."

--Rik

[Charles Krebs]

Rik,

Very nice!

So what it the hardware configuration? Is this direct projection? Did not think you were "into" trinoc heads and photo-eyepieces.

[NikonUser]

That's odd. I assume that Reg Fry (Butterfly Conservation) is the same Reg Fry who edited the book "Habitat Conservation for Insects - a neglected green issue" (which I have) would be more 'careful' in his descriptions.
Not too many skippers in your part of the world; Woodland Skipper Ochlodes sylvanoides is another possibility.

[rjlittlefield]

So what it the hardware configuration? Is this direct projection? Did not think you were "into" trinoc heads and photo-eyepieces.

Yes, direct projection. I have an Olympus CH microscope base with no head. For stuff like this, I just mount a camera on bellows where the microscope head would normally go. That way I get the benefit of stage focusing and also of condenser illumination if I want it (as opposed to my other "open" setups). Looking through the camera eyepiece is useless for seeing any sort of detail, but for framing and focus limits on a stack it's OK.

Not too many skippers in your part of the world; Woodland Skipper Ochlodes sylvanoides is another possibility.

Scanning through Butterflies of Cascadia, I see 5 species of little brown skippers whose distribution maps include my yard. In addition to the two already mentioned, there are Hesperia colorado, Atalopedes campestris, and Polites sabuleti. I suppose the differences become obvious with sufficient study (Pyle writes "...are not as hard to tell apart as they seem"), but I haven't reached that stage of enlightenment yet.

About the captions, it's hard to say. Maybe they were misattributed or edited or provided or rearranged by somebody else.

--Rik

[rjlittlefield]

Well, it stretched both my patience and my skill to net a female while keeping track of the egg that it just laid, but I finally succeeded.

It'll take a while to get a full set of pictures prepared. Here's a quick shot of the ventral.



Front wing length 17.5 mm.

Based on size and ventral appearance, I'm now betting on Atalopedes campestris. If the ID holds up, I'll post out some more description from Pyle's book.

--Rik

[NikonUser]

Sure looks like.
This is essentially a southern and eastern USA species that follows the Pacific coast northward up to Washington state and then detours inland in a narrow strip between Washington and Oregon. It looks like Richmond is at the extreme edge of the species range in the northwest. Good observation and great photo.
My Ref: Brock & Kaufman 2003 Butterflies of North America.

[rjlittlefield]

On closer inspection of the specimen, I'm pretty sure it's Atalopedes campestris. It has the "glassy" spots on the DFW that are supposed to be characteristic of females of this species in our area.

So here's the other information I promised to post out.

From "Butterflies of Cascadia" by Robert Michael Pyle, 2002:

The Sachem [Atalopedes campestris] began turning up in the Willamett Valley in the mid-1960's; Maurita Smyth found it in her Portland butterfly garden in 1986. After several autumns' searching, I found the first specimens on the Washington Side of the Columbia River in a garden near the Vancouver Mall in 1990. Soon thereafter Stuart Chapin photographed it at White Salmon, and Bryant Mather and Patti Ensor turned it up in the Tri-Cities where it is now common. During autumn monarch research in 1996, I found it expanding along the Oregon side of the eastern Columbia. While the species has long been known to undertake seasonal emigrations, this seems to be a case of actual range expansion into the region, parallel to those of the green heron and white-tailed kite. Lisa Reed, who has directed her postgraduate research at the University of Washington toward the evolutionary implications of this phenomenon, found it nearly to Yakima in 1998, and undertook Xerces Society-sponsored research to determine its climatic limits. As of 2000, it had extended north and west as far as Lower Crab Creek near Othello (Pelham).

Whether this points to an ameliorating climate or an organism evolutionarily expanding its cold tolerance or both, this handsome skipper is a welcome addition and should be expected to expand farther north. It remains on the wing when most other species have passed from the autumn scene, usually the only butterfly to be seen when the Northwest Lepidopterists' Association holds its annual meeting around Halloween in Corvallis. Watch for it on frost-free marigold beds up to Thanksgiving. The size, the prominent glassy spot on the forewing of the female, and the exaggerated badge of the male's stigma (the reason for the name Sachem, meaning chief), will give them away.

Considering that Richland is one of the Tri-Cities, I'd say that this record is pretty much a non-event. Nonetheless, it's been interesting learning about these beasts, and I even found (and fixed) a bug in Zerene Stacker as part of the effort. An excellent experience!

--Rik

[NikonUser]

Rik: Ah the beauty of having text written by a local boy! But can highly recommend Jim Brock's book for the rest of NA.

[rjlittlefield]

Ah the beauty of having text written by a local boy!

Yes, it does lend a certain intimacy. I've never met Bob Pyle, only exchanged a bit of email with him. I do know Patti Ensor, and in years past Jon Pelham and I spent many happy hours hanging out and talking bugs. It's always fun to see friends' names in print.

What intrigues me about these skippers is that I got to this place before they did! So this is now at least the third "alien" species that has become common in the 29 years I've been living in Richland. (The other two are Polistes dominulus and Noctua pronuba.) Probably there are others I haven't noticed.

--Rik

[rjlittlefield]

The irregularity at upper right of the egg almost looks like a "transparent foreground" stacking artifact, but it's not. The egg really does have a hard irregular profile at that spot. I have no idea why; I suspect it's an individual defect but I don't even know that for sure.

For the record... I am not an idiot, but sometimes I behave like a skilled actor pretending to be one!

Now 3 days later, I took another look at this egg. Working interactively under a dissecting scope, I could not find a trace of a defect.

Huh?!

So I went back to the original stack and stepped through it slowly and carefully. On about the third pass, I finally caught on.

What I thought was a continuous blade of grass passing behind a defect in the egg, is in fact a broken blade of grass whose end is jammed against the egg, obscuring just a bit of the egg's outline behind it.

Here is a stereo pair that clearly shows the situation. (Zerene Stacker synthesis from the original stack, +-4%, stacking artifacts not retouched.)



I hope you find this interesting, and somewhat less embarrassing than I do!

--Rik

[NikonUser]

Now I know what to look for it's obviously 2 pieces of grass in the original image. I never even thought about the "defect" in the original image. A simple case of distraction; the comment about skipper eggs being "much different" occupied my full attention. Akin to the illusionist's trick - occupy the audience's attention with the right hand while the left hand does the trick.

[rjlittlefield]

Yes, distraction is a powerful force.

For myself, I was distracted by the thought that the anomaly was a stacking artifact, so I studied the stack carefully to confirm that it was actually present in the original imagery. It was. At that moment, the anomaly looked to me like a defect in the egg, and I latched into that interpretation.

My error was further reinforced when I looked at the Silverspotted Skipper egg at the link that you provided (HERE) and saw that it apparently had a defect that looked very much like what I thought I was seeing in my own.

On reviewing the Silverspotted Skipper egg, I now think that what looks like a defect in the shell is actually debris sitting on the surface of the shell.

Interpreting images can be difficult!

--Rik

[rjlittlefield]

Regarding the shapes of skipper eggs...

Shortly after I first posted this topic (now about a month ago), I wrote off to one of my friends who is an guru on the topic of Washington butterfly life cycles. He was out of the country at the time, but has now returned and answered my question. Here's what he had to say:

Grass skipper eggs are mostly like the one you photographed, although there are a couple of exceptions. Euphyes vestris has a bright red ring at maturity but is similar in shape. Thymelicus lineola, a recent European import to WA, is very different; eggs are laid in strings and are elongated and flattened something like cough drops.

Spreadwing skippers are quite different. Most generally resemble brushfoot eggs in shape, higher domed than grass skipper eggs, some barrel-shapped, and are mostly strongly sculptured with vertical ribs. Pholisora catullus is unique, also generally dome-shaped but with very unusual, complex strong sculpture. Heliopetes ericetorum is different again, dome-shaped but with a very intricate cancellate pattern and numerous little spines or tags sticking out, something like a Lorquin's Admiral egg.

Carterocephalus palaemon belongs to a third skipper group, neither grass- nor spreadwing-skippers, and its eggs are similar to the grass skippers.

So now we know: I'm used to looking at grass skipper eggs!

--Rik