How Far Do Hatches Travel?

[NewSal]

pcray1231 wrote:

But heat apparently isn't how they navigate AFTER hatching. While mating, it's an attraction to light (at dusk, they come out of trees in the dark woods and hover over streams with an open canopy, where it's brighter). After mating, and it's time to locate the stream for egg laying, it's horizontally polarized light that attracts them. Starlight or moonlight off of a dark water surface will do it. But off of a dark smooth road surface will as well. And a streetlight over top a dark smooth road surface offers attraction at both stages.

What about the times when spinners swarm and lay eggs during lowlight situations at evening with no moon/or sun? What attracts them towards the water then as apposed to a nearby road? Or is that why they went to the road in the firstplace is due to the lack of guidance from moonlight on water?

 

[pcray1231]

What about the times when spinners swarm and lay eggs during lowlight situations at evening with no moon/or sun? What attracts them towards the water then as apposed to a nearby road? Or is that why they went to the road in the firstplace is due to the lack of guidance from moonlight on water?

I don't know!

Shooting from the hip here, but for one, I'd suspect light levels are what triggers the spinner fall to begin with. i.e. when light levels IN the woods drop to a certain point, they take flight, and head towards lighter areas, which is above the stream.

The situation of "low light" evenings would be heavy cloud cover. That low light situation happens earlier, and hence the spinners fly earlier, with still some daytime left. So when they leave trees to dance, and when they stop dancing and fall spent is all a function of light levels. Every day there's an appropriate transition period, but weather determines whether it's early or late. Sunny days are when things happen late.

Of course, you could have an evening where it's been sunny and clouds up very suddenly at dusk as a line of storms rolls in or something. In that case, I'd guess that either a higher % get lost, or else they just go back to the trees and do their dance the next night. Might depend on species too.

And that situation is often associated with wind as well, which I'm sure has quite an effect!

 

[franklin]

pcray1231 wrote:

I'd guess heat. At least for evening hatches.

Heat, i.e. water temperature, is the biggest thing regarding the timing of the hatch. First you need mature nymphs, so that's the total "temperature days", meaning over the entire year, not just during the season in which they hatch. Then, having that, water temperature offers a "trigger", so when it reaches X degrees the bugs that are mature start to hatch en masse.

That's why you typically have larger individuals within a species hatching first. Those nymphs were mature long before the trigger came. Later in the hatch, the limiting factor is the maturity of the nymphs, so they hatch as soon as they are able.

Diurnal cycles, and perhaps moon phase, weather (cloud cover), pressure, air temperature, are potentially important as well, most of which are harder to prove.

But heat apparently isn't how they navigate AFTER hatching. While mating, it's an attraction to light (at dusk, they come out of trees in the dark woods and hover over streams with an open canopy, where it's brighter). After mating, and it's time to locate the stream for egg laying, it's horizontally polarized light that attracts them. Starlight or moonlight off of a dark water surface will do it. But off of a dark smooth road surface will as well. And a streetlight over top a dark smooth road surface offers attraction at both stages.

I'm not talking about what makes them hatch. I'm referring to how they find the stream and why they sometimes target roads.

I bet Mike has some ideas. Would think there has to be studies done that identify the means.

 

[pcray1231]

Yeah, I'm kinda giving the result of the studies I've found.

Light in general, with a particular affinity for horizontally polarized light (like would be reflected from a smooth horizontal surface, like a stream).

 

[turkey]

This guy was on my house this morning. Any idea on the I.D. Pat or anyone?

 

[pcray1231]

Looks like a March Brown to me. Spinner stage. Some will call it a "gray fox", which is still the same species. The species just has a lot of variation within and the "gray fox" is a name for those on the small and light colored end of the spectrum.

Maccaffertium Vicarium if you want the latin...

 

[turkey]

pcray1231 wrote:
Looks like a March Brown to me. Spinner stage. Some will call it a "gray fox", which is still the same species. The species just has a lot of variation within and the "gray fox" is a name for those on the small and light colored end of the spectrum.

Maccaffertium Vicarium if you want the latin...

Nice. Thanks. I was thinking MB but it seemed a little small to me. My enthusiasm for taxonomy has waned over the years.

 

[franklin]

pcray1231 wrote:
Yeah, I'm kinda giving the result of the studies I've found.

Light in general, with a particular affinity for horizontally polarized light (like would be reflected from a smooth horizontal surface, like a stream).

That makes sense. (pun intended) They don't need to discern objects in great detail. They just need to sense a general direction.

I have to admit I should have realized a PCRAY response and read the whole thing. I quit before finishing the last paragraph.

 

[pcray1231]

They don't need to discern objects in great detail. They just need to sense a general direction.

I feel semi-confident that it's all about light levels to begin with.

i.e. bug sitting in tree in forest. When that forest gets dark enough, it takes flight, and looks for light in general. What's the brightest area as dusk approaches? Well, it's right over the stream corridor, where the canopy opens up! So that's where they go.

Now, even that light begins to fade. Now there's just this ribbon of water reflecting the remaining light. So they follow it. Most of it is polarized light, which they are even more attracted to.

Till the point where it gets so dark that even that light is gone, at which time they fall spent. Or go back to the trees, or whatever.

I'm sure each species is a little different, but that's the main view, IMO.

 

[Chaz]

I was in Easton one morning during the summer a few years back, not near either river or the Bushkill. There were mayflies everywhere. At least a mile from the Lehigh, more than that from the 'D' and Bushkill. It was daylight.