30 November 2011

Honduras: the odes of Pico Bonito

We made another trip south this past holiday weekend (November 24-28, 2011). This year we visited Honduras and stayed at The Lodge at Pico Bonito (15.6929, -86.9022) near La Ceiba.

Travel to the location was easy. We flew into San Pedro Sula, then one has two options to arrive at the lodge: fly to La Ceiba or drive 2.5 hours via car. We chose the latter since this gave us a chance to see a bit more of the country. The highway was in amazing condition compared with other roads in Central America, but we soon determined why this was the case. Heading east from the airport, we soon encountered oil palm plantations which have taken over vast areas of land and large variety of issues. We then drove past immense areas of fruit production (bananas and pineapple). Upon arriving in El Pino, we turned onto a nondescript road leading through secondary growth forests and cacao plantations. When the forest became thicker, we knew we were close since the lodge is at the edge of Pico Bonito National Park.

The Lodge at Pico Bonito includes several buildings (lodge, restaurant/bar, cabins) and an outdoor pool. The grounds and gardens between the cabins are a mix of manicured lawn, flower beds, and an old cacao plantation.

These gardens were good areas to find young individuals of a variety of species.



Digiscoped female skimmer (Orthemis sp.).

The porch of our cabin (#2) provided the location of our favorite ode observation.



Megaloprepus caerulatus - our favorite ode in the world.

Megaloprepus caerulatus - close up of wing tips.

The property is situated along a ridge between two rivers (Rio Coloradito to the west and Rio Corinto to the east). These clear, swift-flowing mountain rivers didn't provide much in the way of odonata observations, but they were quite beautiful. The only species observed next to a river was one female Band-winged Dragonlet (Erythrodiplax umbrata). Perhaps this was due to the time of year?

Rio Coloradito.


Rio Corinto.

Each afternoon we took a walk to the Butterfly House since the trail went through an old cacao plantation with a couple of open areas. The clearing between the larval house and the adult houses was a good area to look for odes and leps.

The ubiquitous dragonlet Band-winged Dragonlet (Erythrodiplax umbrata).


Pin-tailed Pondhawk (Erythemis plebeja).

Erythrodiplax fervida. She looks like
she is about to do a swan dive.



On our last full day (11/27/11), we hired one of the lodge's guides Elmer Escoto for a morning bird walk. We went to a new trail created west of the Rio Coloradito. The area on the left side of the photo below.


We crossed a small stream in the forest that had a few patches of sunlight. That's all we needed to pull out the net and find a couple more species of odes. We turned our bird guide into a Honduran dragonhunter.

Our guide Elmer Escoto caught the rubyspot for us.


Hetaerina capitalis.

There were also several Argias present. These appeared to be of the Argia oculatus complex, type B.


Finally, that afternoon (11/27/11) we witnessed the large dragonfly movement that the Lodge's naturalist James Adams had mentioned to us when we arrived. On our walk to the Butterfly House, we spied 1000s, if not 10s of 1000s, of odes flying in an easterly direction. Here's a distant photo (click on it to view large...all the small specs are dragonflies):



...and a digiscoped shot through my binoculars:


This flight continued nonstop throughout the afternoon. Anytime we looked up through the trees, the numbers continued. We're not sure how many species were involved, how many days this continued, or the reason for the movement.

List of species observed and locations during our brief visit:
1. Hetaerina capitalis = small forest stream west of Rio Coloradito
2. Megaloprepus caerulatus = cabin #2
3. Argia oculata complex, type B = small forest stream west of Rio Coloradito
4. Telebasis sp. = small forest stream west of Rio Coloradito
5. Black Pondhawk (Erythemis attala) = Butterfly House vicinity
6. Pin-tailed Pondhawk (E. plebeja) = Butterfly House vicinity
7. Great Pondhawk (E. vesiculosa) = the Lodge's gardens
8. Erythrodiplax fervida = Butterfly House vicinity
9. Band-winged Dragonlet (E. umbrata) = any open area
10. Roseate Skimmer (Orthemis ferruginea) = Butterfly House vicinity

10 November 2011

Updated Late Dates 2011

The mild November weather allowed us to check on a special species in Michigan. Great Spreadwing (Archilestes grandis) has only been found in Livonia through the years. Julie saw individuals again a month or so ago, and had noted goldfish swimming in one of the small pools of the creek. (this may not bode well for the odonata species).

On November 6, we waited until the frost thawed and then headed to THE location. Within a minute I found a male Eastern Forktail (Ischnura verticalis) which marks a new late date.


Julie noted that she now saw a bluegill in the same pool that had goldfish previously, and the location where the A. grandis were easiest to find in past years. (uh oh) I walked further down the creek towards I-275 between the newer buildings. In the first sunlit, sheltered location I flushed a coupled pair of Great Spreadwings! Soon after I saw a solo male and either the same or another coupled pair. This marks the new late date for Michigan by 1 day.


These may be the last species the two of us see in Michigan this season, barring Autumn Meadowhawks (Sympetrum vicinum).

06 November 2011

Last Odes of the 2011 Season in southeastern MI

While walking around campus at my workplace in Farmington Hills, Oakland County, MI, during lunch hour on October 24, 2011, I found 3 of the last dragonfly species of the season.

3+ Familiar Bluet (Enallagma civile)
1 Common Green Darner (Anax junius)
4+ Autumn Meadowhawks (Sympetrum vicinum)

Over the following days I kept an eye out for these since the late dates for specimens was approaching.

On October 31, I was able to find a female Eastern Forktail (Ischnura verticalis) for what I believe is a new late date for a MI voucher. The previous late date in the MOS database was an individual I had on 10/07/07.
This image is of a female I found in Monroe County earlier in October:


On November 2, I found one female and one male Familiar Bluet (E. civile)! This, too, is what I believe to be the latest date for a MI voucher. The previous late date in the MOS database was an individual I had on 10/19/10. Here is the male:


Today is one of the truly nice days remaining for this year. We'll head out to look for the last possibilities of flying damsels around here.

19 October 2011

Aeshna ID: Canada versus Green-striped

In our quest for Canada Darner (Aeshna canadensis) in Wayne County, we have come up with a number of locations and specimens of the similar Green-striped Darner (A. verticalis). While there is a historical and possible photo record for Canada (CADA) for the county, we've had no luck finding this species over the last ten years. We've only found one Green-striped (GSDA), in 2003, prior to this year, when we found many.

Most field guides present differentiating these two species as fairly straightforward. We've found ID more problematic, although we are hampered by a lack of live CADA material to work with. This post will go over these two species, and (necessarily) feature the variability of GSDA that would complicate field ID.

Here are the characteristics typically cited to separate the two species.

Field characteristics

Color of thoracic stripes: Usually blue in CADA, green in GSDA. However, male CADA often have stripes that are greenish ventrally or sometimes all green. Meanwhile, the rear stripe in male GSDA is sometimes blue-green dorsally.

Dot on thorax: CADA usually have a yellow dot between the two thoracic stripes. This feature is also sometimes present on GSDA. We have found it present at least half the time in our area.

Male Green-striped Darner. Rear thoracic stripe partly blue,
spot between stripes present. Livingston Co., MI

Male Green-striped Darner with very bluish stripes and thoracic
spot absent. Wayne Co., MI

CADA females come in a green-striped form, and some female GSDA are blue (rarely). Cold individuals of either species can be dull and confusing. Many guides agree that green females are probably impossible to tell apart without close examination in the hand.

Female Green-striped Darner with bluish and green abdominal spots;
thoracic spot absent. Wayne Co., MI

Female Green-striped Darner with bluish abdominal spots;
thoracic spot present. Note that both females are missing cerci,
which presents another problem (see below). Wayne Co., MI

Shape of thoracic stripes: Front stripe is supposed to be deeply notched in CADA, not so deeply notched in GSDA. The dorsal "flag" (the part of the front stripe that runs along the base of the wing) of CADA narrows, often becomes wider in GSDA, as is evident in the photos above.

This Aeshna has a "flag"that narrows, which could indicate
Canada, but the thoracic stripes are greenish, as in
Green-striped. We were unable to collect this one to verify
identity. Livingston Co., MI

Males, spot on abdominal segment 1: Usually only slightly pinched in CADA, deeply notched or bifurcated in GSDA. I've added this feature per Reuven's comment below. Here is a composite of GSDAs showing variability, with a red arrow in the first photo pointing out s1.


Certainly variable, but often distinctly "bi-lobed." I hestitate to link to online photos since I don't know if they are always correctly identified, but here are some shots that I believe are of genuine CADA showing s1.

Minnesota, s1 nearly entire.
Montana, s1 notched.
Ontario, s1 notched.
Presumed Montana, s1 deeply notched. This photo, by the way, is worth viewing original size, as there is the head of a hymenopteran latched on to one of the darner's legs!

While apparently variable in both species, this could be reliable, especially in combination with other features.

Face: Black band across the labrum in CADA, brownish edge in GSDA.

Canada Darner, black labrum.

Green-striped Darner, brownish labrum.
This seems like it also might be reliable, but we have not looked at enough CADA to be sure. One thing we've noticed about this feature, at least in GSDA, is the variability of facial markings. Many have random botches and spots. We wonder how prevalent this is in CADA, and if it muddies the diagnosis of labrum color. This photo of a putative CADA, also shows a weird blotchy face. Here are just a few GSDA faces.


In-hand characteristics

We have had more success examining these two species in the hand under very close magnification, but the keys and characteristics can be puzzling without experience or comparative material. Here are some of our experiences.

Males

In males, the shape of the cerci are similar in both species. However, as most keys note, the top margin of the superior claspers of male CADA have tiny teeth; these are absent in GSDA. These usually cannot be seen in the field or a photograph, but are said to detectable by running a finger across the cerci. I'm not sure this would be a slam-dunk even for Helen Keller. These teeth are very tiny.

Arrow pointing to teeth on top margin of CADA male cerci.
Crawford Co., MI

What we have found to be most obvious (once you know what you are looking at) are the "anteromedial process of each anterior hamule," or an aspect of the naughty bits. They are, in much more simple language, pointed in toward the rear in CADA and pointed at each other in GSDA. First, let's look at the diagram from DONA*. The red arrows show these bits, and the orientation is such that the top of the diagram is the direction of the heads of the dragonflies:

And to put this in some context, here is what it looks like. We used a Dino-Lite Digital Microscope to take these photos.

Male CADA, arrow pointing to rightmost anteromedial process. Note that in CADA, these
two paired structures look like open gates, pointing to the head of the insect.
Male GSDA, arrow pointing to rightmost anteromedial process. Note that in GSDA, these
two paired structures look like closed gates, with the tips pointing to each other.

These things are very tiny and hard to see! But if you can get the right look, they are diagnostic.

By the way, although it is not pictured or mentioned consistently in all keys, both species have a little tubercle or bump on the top of abdominal segment 10. It's visible in the photo above of the male CADA cerci.

Females

Most authors acknowledge that green-colored females of these two species can't be separated in the field, or with photos. DONA's key points us to the structure of the ridge of the genital valves, and provides us with this diagram:

These two look pretty similar. The shape of the cerci is different -- but they are often broken off. We haven't caught any candidates that still had their cerci. Those being absent, we weren't sure, even with the little arrows, precisely what structure we were supposed to be examining (in the hand, they have a lot of little ridges and flanges going on in those parts). Another diagram is helpful:

This shows that the genital valves in question are the things that the little hair-like styli come from. Once we saw that, we knew what we had to look at. The key notes that in CADA, the basal third of these valves has a weakly developed ridge, which is well developed in GSDA. We must admit, looking at a single specimen we were still uncertain. It looked kind of like either one of them. For what it's worth, here is a GSDA, with the contrast tweaked to show the ridge.


This winter, I'll try to pull out some specimens at the University of Michigan Museum of Zoology Insect Division and take a look at further material. Even better, maybe I can convince Mark O'Brien to take some digital photos. Even better than that, maybe next year the Urban Dragon Hunters can find some Canada Darners of our own.

*Needham, J.G., M.J. Westfall, Jr. and M.L. May. 2000. Dragonflies of North America, revised edition. Gainesville: Scientific Publishers. The granddaddy of Odonata keys.

04 October 2011

Circus of the Spineless

Way back in the Jurassic period of the Internet, Julie was one of the founders of the blog carnival Circus of the Spineless, a monthly compendium of blog posts on invertebrates. It's high time we start participating once again in CoTS. This month, CoTS #66 is hosted by another long-running blog, Wanderin' Weeta. It includes our post on Striped saddlebag and the value of vouchers, and a bunch of other invert posts, including two more on Odonata. Go take a look, and consider submitting a post to a future issue.

17 September 2011

Green-striped Darners

We saw our first Green-striped Darner (Aeshna verticalis) in October of 2003 at the hawkwatch (formerly SMRR, now the Detroit River Hawkwatch) at Lake Erie Metropark.

Years have gone by without seeing others and now, in the past week, we have found multiple individuals at two more locations in Wayne County.

On August 28th, we visited Crosswinds Marsh in an attempt to confirm Canada Darner (A. canadensis). At one point in the NW area of phase I, a mosaic darner flew across the trail and perched in a small tree. This turned out to be a female Green-striped Darner (A. verticalis). This shot shows the obtuse angle of the anterior lateral thoracic stripe:


This shot shows the dorsal patterning:


This shot shows the frons and the face:



Several days later on September 3rd we visited Maybury State Park. In the northwest area of the park, we found several darners working an open area. We captured a pair of Green-striped Darners (A. verticalis).

Side view of the male:


Dorsal view patterning:


Another good feature for confirming ID of A. verticalis is the lack of "teeth" on the dorsal surface of the cerci. I'm not sure one could see "teeth", or bumps, in this photo even if it was a Canada (A. canadensis), but in the hand and under a microscope the "teeth" were absent:


The female lateral view:


It has been fun gaining more experience with the Green-striped Darners (A. verticalis), but we still need to find that elusive Canada Darner (A. canadensis) in Wayne County. In the coming days, we'll add more information about how to differentiate A. verticalis from A. canadensis.

13 September 2011

An insect in the hand is worth more than a book cover

At the risk of sounding like (even more of a) stick-in-the-mud regarding the value of vouchers, here is a great example of not always being able to trust photographic identifications of insects:

This is a real book, thankfully out of print, which has a fly illustrating the cover. It was highlighted on the Scientific American blog of Alex Wild in a post on misidentified insects in the media.  Alex has his own excellent blog, Myrmecos, where he has shown that even National Geographic isn't immune to these mistakes (nor The Learning Channel, a Discovery company). Surely they should know better. And so should the "experts" at pest eradication companies around the country, but look at the array of things that are not fire ants displayed on their web sites.

Unfortunately, mislabeled photos online often come back to haunt us, as the misidentifications may be passed on and perpetuated. I'm not going to beat a dead horse here. I'll just say be careful when using photos to ID insects, don't just label something online if you aren't sure (ask for help!), and correct your mistakes in a timely manner.

[stands down from soapbox]

10 September 2011

Flag-tailed Spinyleg confirmed for Lenawee County

We had heard that Flag-tailed Spinylegs (Dromogomphus spoliatus) were observed at Indian Crossing Trails Park in Tecumseh in the mid-August. This is only the third location they've been observed in Michigan so we had to confirm the record. The first record was from Oakwoods Metropark in Wayne County and earlier this August a photograph was obtained of an individual at Pte. Mouillee SGA in Monroe County.

We arrived to the park late in the morning on August 27, 2011 and almost immediately flushed a spinyleg from the rip rap bordering the millpond next to the community center. We obtained several photographs at a distance, but they were very skittish.
Some through binoculars:


and others with Julie's macro lens:


Now the challenge was to net one. We worked the edge of the dam repeatedly, trying to get in a position to approach the individuals without casting a shadow and having room for a swing of the net. After 45 minutes or so, I was able to trap one on a flat piece of concrete with Julie helping to herd it. This male (D. spoliatus) confirms the record for Lenawee county and was one of ~10 individuals present:


...and this photo shows its spiny legs and the flag tail:


While chasing the target species, we found several other great dragonflies. A couple Black-shouldered Spinyleg (Dromogomphus spinosus), such as this male:


A few Royal River Cruisers (Macromia taeniolata), with this male possibly representing the first record for Lenawee County:


Many Smoky Rubyspots (Hetaerina titia), which seem to be everywhere this year:


A few Eastern Amberwings (Perithemis tenera), such as this female:


We also had heard that a Dragonhunter (Hagenius brevistylus) or two had been observed recently, but no luck this day. We had observed a male a few years ago, but couldn't obtain any photos. Indian Crossing Trails Park is a must for a return visit in the future.