Thursday, July 17, 2014

Filigree Skimmer State Record for Colorado

Earlier this month, on July 3, I was fortunate enough to be in the right place at the right time to make an important observation and documentation of a male Filigree Skimmer, Pseudoleon superbus, in Colorado Springs. This represents the first confirmed state record for the species as well as a significant northern range extension.

There is a vast series of vacant lots up the hill from my home that includes a narrow, deep riparian corridor through the otherwise degraded shortgrass prairie habitat of the hills. The channel carries water dependably throughout the year, and trickles into Sand Creek, a wide, mostly dry riverbed that sometimes runs in very shallow, meandering rivulets (except during storms when the volume is much greater).

The Filigree Skimmer was frequenting the large pond shown in the habitat shot above, repeatedly perching on the rockwork between forays up and down the watercourse. At first I assumed it was probably a Common Whitetail, Plathymis lydia, but something about those wing markings looked a bit off. Noting where it was repeatedly perching, I worked my way into a position where I could get the images shown here, taken with a Canon Powershot SX50. That powerful zoom sure comes in handy at times like this.

The near pristine condition of the specimen makes me wonder if perhaps the species does breed here rather than migrate up from the species' usual range of southern and central Arizona, New Mexico, and western and central Texas. This is essentially a subtropical species found as far south as Costa Rica, though mostly in dry uplands there.

Male specimens have the wings mostly blackish, especially the hind wings. Females have much less black, arranged in an abstract, reticulated pattern. Both genders have the "pinstripes" on the eyes. The total body length varies from 38-45 millimeters, and the length of the hind wing averages 30-35 millimeters.

The preferred habitat for the Filigree Skimmer is a rocky stream or river with a slow or moderate current, usually in an open setting. The little creek where I found it certainly fits the bill. Females lay their eggs by hovering and dipping the tip of their abdomen into the water, usually in the vicinity of algal mats or piles of detritus. There is plenty of both in this location, too.

Bill Maynard, our local authority on Odonata, asked for directions to the spot where I saw the skimmer, and he visited on July 4 but had no luck. Ironically, he did observe several species of damselflies that I had not yet documented for the area. He also got a lovely image of a Gulf Fritillary butterfly, as likely to be seen this far north as the Filigree Skimmer.

My record of the Filigree Skimmer is awaiting confirmation at Odonata Central. I encourage my readers to consult that website to see what species have been recorded in their state or county, and add their own observations as they deem appropriate.

Just because you have "never seen this (insert name of insect or other arthropod here) before in (your) life," and you have "lived here for (insert number of decades or years)," does not mean that it is something rare or exotic or otherwise novel. BUT, sometimes it really is a unique find worthy of note. That is your take-home lesson for today: Be observant and don't assume anything. It helps me to have some knowledge of what should and should not be here in Colorado, but you, too, can make significant contributions to our collective scientific knowledge.

Source: Paulson, Dennis. 2009. Dragonflies and Damselflies of the West. Princeton, New Jersey: Princeton University Press. 535 pp. I highly recommend this reference, well worth the price.

Thursday, June 26, 2014

Computer Woes

I regret to inform my loyal readers here that I am having serious computer issues. I am writing this from my wife's machine, and plan to take my own computer to the repair shop ASAP. That might be Monday at the earliest, and how long they will need it I have no idea. Hoping my disk isn't bad, but it is a relatively "old" HP Premium Elite HPE I purchased back in....2010?

I've backed up all my edited images, documents, etc, but I have thousands of unedited photos that I don't have room to back up on my external hard drive. So, I will still be able to do some blogs in the future, even if I face the worst-case scenario. I just really hope that doesn't happen.

Thank you for your understanding and patience during this trying period. I will not be posting for the immediate, foreseeable future, but have no plans to terminate the blog.

Tuesday, June 24, 2014

Backswimmer or Water Boatman?

Just a short post for “True Bug Tuesday,” addressing an identification problem that many people admit having. I am not an expert on aquatic insects by any means, but differentiating backswimmers (family Notonectidae) from water boatmen (family Corixidae) is fairly straightforward.

Backswimmer swimming upside down

My own experience has shown that backswimmers are generally far more commonly seen by the casual observer than are water boatmen. Backswimmers can even turn up in the fountains, swimming pools, and other artificial water environments water boatmen rarely frequent. Now, if you bother dragging a net through the water, especially over the bottom of a pond or slow-moving stream, then you may see water boatmen at least as frequently as backswimmers, if not more so.

Turn on lights at night anywhere near water and you may bet large numbers of water boatmen showing up, flailing about on the ground. Both water boatmen and backswimmers can fly as adults, but backswimmers seem to be mostly diurnal and will rarely if ever be attracted to lights at night.

Water boatman attracted to light at night

Physically, both kinds of insects do superficially resemble each other. Both are more or less oval or bullet-shaped, and the hind legs are very long, modified for rowing through the water. That is pretty much where the similarities end, however.

Adult backswimmers, at least those of the common genus Notonecta, are much larger than the average water boatman. Backswimmers, in cross section from front to back, have distinctly triangular bodies. They are shaped more like a boat than a water boatman. The top of a backswimmer is keel-like, affording it the ability to swim very rapidly upside down. Water boatmen are more flattened top to bottom.

Water boatman

The front legs of backswimmers are short, but shaped normally, with no obvious modifications. The front legs of water boatmen have spoon-shaped tarsal segments for scooping organic matter into the mouth of the bug. While backswimmers have a four-segmented rostrum (“beak”) they use to bite prey, water boatmen have the beak fused to the head. The face of a water boatman reminds one of an imperial storm trooper from Star Wars.

Water boatman. Note scoop-like front "feet"

Most water boatmen are brown on top, marked with fine, transverse black lines, giving them a slightly corrugated appearance. Backswimmers, by contrast, are usually boldly marked with patches of black, yellowish-brown, red, or white.

Top of backswimmer, © Lynette Schimming

Backswimmers frequent open water where they actively pursue mosquito larvae and other small aquatic insects. Water boatmen normally cruise the bottom, stirring up muck and microscopic organisms that they feed on. Consequently, water boatmen are often difficult to see when you are looking into the water. They are camouflaged, and/or they hide under leaf litter and other bottom debris.

Backswimmer, © Margarethe Brummermann

Look for backswimmers surfacing to take in air with those hydrophobic hairs around their rear end. The hairs also go down the middle of the underside of the abdomen, helping to trap air for their underwater lifestyle.

Source: Lehmkuhl, Dennis M. 1979. How to Know the Aquatic Insects. Dubuque, Iowa: Wm. C. Brown Company Publishers. 168 pp.

Saturday, June 21, 2014

Termite Swarms

It is, was, or will be termite swarming time across much of North America. Contrary to popular “knowledge,” we do have termites here in Colorado, at least below 7,000 feet elevation. Our most abundant species is the Arid-land Subterranean Termite, Reticulitermes tibialis. Back on the morning of May 24, I happened upon a colony that was liberating its “alates,” winged reproductive termites that will mate with members of other colonies and begin their own new colonies.

Subterranean termites actually nest in the soil, consuming wood and other sources of cellulose that are buried in the soil or in contact with the soil. Turning back a board out in the shortgrass prairie here in Colorado Springs is likely to uncover foraging termites that quickly seek shelter back in their underground tunnels.

A typical termite colony consists of a “king” and “queen,” a male and female pair that founded the colony and bond for life. That life can be a decade or more for the queen. Her sole mission is to lay eggs, and she is a bit of a bloated creature, her abdominal segments distended. Still, she can move around rather freely, in contrast to the huge, immobile queens of some tropical termite species that exist trapped in a “royal cell” defended by soldier termites.

Soldier termite

Subterranean termite colonies have soldiers, too, with large, rectangular heads and oversized jaws they can use to dispatch ants, the chief predators of termites. Most of the colony is made up of a “worker” caste that does the foraging, underground tunnel- and above-ground tube-construction, tends the queen and newly-minted immature termites. All the young termites in the colony are workers, but have the potential to become soldiers or reproductives. In situations where a queen dies, or becomes separated from part of the colony, some workers can metamorphose into supplementary reproductives capable of laying eggs themselves within their parent colony.

Once each year, a mature colony launches a swarm of winged male and female termites that goes in search of mates in hopes of starting new colonies. Arid-land Subterranean Termites typically swarm from January to March at elevations below 4,000 feet, and in June or July above that elevation. The alates I witnessed were issuing from imperceptible cracks in the soil, like toothpaste oozing from the tube. Check out the video below:

Termite swarms are like a buffet to insectivores, and it was only a matter of minutes before tiny ants set upon the lethargic alates, carting them off by the bushel to feed their own ant larvae in some subterranean nest. Birds, amphibians, lizards, spiders, and countless predatory insects feast on the living confetti.

Ant carrying off alate termite

Those female individuals that do survive are mostly wind-blown across the landscape, hoping to land in the vicinity of an unrelated colony that is also swarming. The female sheds her wings and emits a pheromone (chemical scent) that attracts males. Once a suitable mate appears, they mate and begin searching for a nesting site. The pair creates a small chamber underground or beneath a stone or other object, and she begins laying eggs.

Alate termite with hind wings stuck together

How do you tell winged termites from winged ants? Winged termites have two pairs of wings of equal length, whereas ants have the front wings much larger than the hind wings. Ants have long, elbowed antennae, while termites have shorter antennae with segments of equal length. Ants have the body clearly divided into three sections: head, thorax, and abdomen. Winged termites have those divisions much less obvious. The thorax and abdomen seem to merge seamlessly in termites.

Pair of winged ants, Crematogaster sp.

Subterranean termites are not large insects. Even the alates of the Arid-land species measure only 10 millimeters from nose to wingtip. Soldiers are a mere 3.5-4.5 millimeters. This species occurs throughout the intermountain west of the U.S., eastward to Missouri, Arkansas, and Texas, south to Mexico. Other species of Reticulitermes range in other parts of North America.

A termite swarm outdoors, away from your own home, is a spectacle to behold. An indoor swarm….not so much. Still, to suddenly witness an enormous population of normally unseen animals erupting from the landscape is simply stunning. It helps to know that, in nature, termites are valuable decomposers that turn and aerate the soil while breaking down cellulose into nutrients now available to other living organisms.

Notes: Fairly recently (2007), termites became reclassified. Once they were members of their own order, the Isoptera. Today they are recognized essentially as “social cockroaches,” lumped with roaches in the order Blattodea.

Termites, unlike carpenter ants that merely chew cavities in wood to make nesting space, actually do eat wood. They can do this thanks to a gut fauna of microbes that efficiently break down cellulose. The bacteria, archaea, and protozoans exist only inside of termites, and are acquired by young termites when they consume fresh fecal material of adult termites, or are fed regurgitated, partially-digested food by worker termites.

Sources: Cranshaw, Whitney and Boris Kondratieff. 1995. Bagging Big Bugs. Golden, Colorado: Fulcrum Publishing. 324 pp.
Helfer, Jacques R. 1972. How to Know the Grasshoppers, Cockroaches, and Their Allies (2nd edition). Dubuque, Iowa: Wm. C. Brown Company Publishers. 359 pp.
Noll, Kenneth. “NSF Termite Project,” Noll Lab.
”Termites Are Cockroaches After All,” Natural History Museum (London) News.