Moth Flies

It’s a moth! It’s a fly! It’s….a “moth fly!” So goes the confusion upon encountering one of the most common yet confounding dipterans. Moth flies belong to the family Psychodidae in the order Diptera. Most people have seen these diminutive, fuzzy creatures in the bathroom, perched on the side of the sink basin, or on a nearby wall. Where do they come from? Are they harmful?

The answer to the second question is easier than the first. Moth flies are not harmful, at least in the sense of public health. They do not bite, unlike their cousins the sand flies, also in the family Psychodidae, but members of a different subfamily. Sand flies not only bite, but are vectors of leishmaniasis, a parasitic disease occurring mostly in the tropics. Moth flies are mostly a nuisance, though they can reach high population densities around sewage treatment plants.

Adult moth flies are active mostly in the evening hours, and are attracted to lights after dark. Consequently, they may easily enter the home through an open door or window. While they can breed indoors (more on that later), they normally seek wet, decaying organic matter where the female can lay from 30-200 eggs in a loose cluster. Typical sites that attract them include clogged rain gutters, compost heaps, birdbaths, sewer drains, septic tanks, and filter beds at sewage treatment facilities.

I find it amusing that the scientific name of one of the most common species of moth flies, the “Filter Fly,” is Clogmia albipunctata. They certainly don’t cause clogged drains. In fact, they may be better at preventing clogs than a bottle of Draino or Liquid Plumber. This common household species can carry out its life cycle inside the pipes under your sink or shower, no matter how clean your bathroom is.

The eggs hatch between 32 and 48 hours after the female lays them, the larvae proceeding to feed on algae, fungi, microbes, and other organic matter in the gelatinous film of goo lining the average sink drain. I suspect that the many questions I receive about “worms” in the sink or shower refer to mature larvae of Clogmia that are seeking a place to pupate, or that are flushed from their normal feeding niche. It takes a larva from nine to fifteen days to reach the point where they are ready to graduate to the pupal stage. The pupa usually resides on the surface of the same organic film as the larva inhabits. An adult fly emerges from the pupa in an astounding 20-40 hours.

Moth fly larvae are actually considered beneficial organisms in the treatment of municipal sewage, so bear that in mind the next time you encounter one. You have to admire them just a little bit for capitalizing on the artificial habitats we have inadvertently created for them.

Sources: For way better images of adults and larvae, take a look at this remarkable life cycle series shot by my good friend Ashley Bradford. She is definitely not the squeamish sort! Also check out this fantastic fact sheet produced by the Connecticut Agricultural Experiment Station. It gives more detailed information than I have room for here, including how to prevent infestations and deal with existing ones.

Wasp Wednesday: Pachodynerus

Last week I introduced you to a social wasp called the ”Mexican Honey Wasp” in the family Vespidae, subfamily Polistinae. That species appears to be the model for a mimicry ring involving several unrelated solitary wasps, and a type of soldier fly….and those are only the ones I personally know about.

One of the best of these mimics is Pachodynerus nasidens, a mason wasp in the family Vespidae, subfamily Eumeninae. It goes by the common name “Keyhole Wasp,” but I have heard that epithet applied to other wasps as well, so will stick with the Latin here.

The markings of this wasp are essentially identical to those of the Mexican Honey Wasp, and a cursory look is not enough to distinguish the two. Oddly, Pachodynerus nasidens has at least a slightly broader range than Brachygastra mellifica, occurring in southern Arizona, Brownsville, Texas, and Plantation Key in Florida, as well as throughout Mexico, Central America, and the Antilles. Interestingly, it has been “exported” accidentally to Hawaii and Micronesia. The U.S. range strongly suggests that the Mexican Honey Wasp should turn up in the same areas (indeed it is found in Texas but is thusfar considered absent from Arizona and Florida).

Females of the solitary Pachodynerus nasidens build mud cells inside the abandoned nests of mud daubers (Sceliphron caementarium and Trypoxylon politum), or in other pre-existing cavities. It has been rumored that the females sometimes build their own free-standing mud nests, and these images would tend to substantiate that supposition. Inside, each cell is provisioned with paralyzed caterpillars that will be the food for the single larval wasp that develops there.

Enemies of this wasp are many, and include at least one species of cuckoo wasp in the genus Chrysis. Recall that cuckoo wasp females lay their eggs in the nests of other wasps. Melittobia chalybii, a tiny parasitic wasp in the family Eulophidae is also known to infest the nests of P. nasidens. Likewise, the sarcophagid satellite fly Amobia floridensis can infiltrate a nest, depositing her tiny larvae there. Acrobat ants (Crematogaster sp.) are recorded as predators, presumably breaking into nests to prey on the immature stages of the wasp. Wedge-shaped beetles in the family Ripiphoridae, genus Macrosaigon carry out their bizarre life cycle inside the nests as well.

There is another species of Pachodynerus found here in Arizona: P. guadulpensis. Older references list it as P. praecox. It ranges into from Mexico into southern California, Arizona, and Texas. Note the extra yellow stripe across the *front* of the abdomen that distinguishes this species from P. nasidens. The specimen imaged above was discovered in the butterfly garden at the Tucson Botanical Gardens in the middle of Tucson.

I’m hoping to learn more about these wasps, and complete my findings on the mimicry ring, sometime in the not-too-distant future. Meanwhile, please share your own observations here, and in your own blogs.

Wasps to the Rescue

Lest you think that wasps are no more than a novelty of nature, or at best natural pest control agents, take a look at this article in the New York Times. Many thanks to my friend Art Evans for sharing the story of the “Wasp Hound” on Facebook.

I have another personal friend who is (or was) engaged in similar research whereby certain insects could be reliably employed to detect explosives, and/or search for human survivors amid piles of rubble too inaccessible or unstable for firefighters and EMTs to negotiate. There is real potential here and it would literally pay to continue refining the capabilities of “bugs” to aid in the war against terrorism.

The only question I have after reading the above article is “So what species of wasp are you using?!” Details, details…

Wasp Wednesday: Brachygastra mellifica

I recently had the honor of reviewing an article about wasps destined for a national magazine. One of the few inaccuracies I found was the assertion that while bees make honey, wasps do not. Putting aside the fact that only social species in the family Apidae make and store honey (the vast majority of bees are solitary and do not manufacture honey), it is also incorrect to say that no wasps produce this sweet substance. Case in point: Brachygastra mellifica, a tropical social wasp that sneaks over the border into Texas and possibly Arizona.

Known as the “Mexican Honey Wasp,” this species is a member of the family Vespidae and the subfamily Polistinae. They are small insects, only 7-9 millimeters in length. The specimen imaged here is one I spotted at a trailer park resort in Mission, Texas, adjacent to Bentsen-Rio Grande Valley State Park. It was one of several different hymenopterans lapping up honeydew from an aphid-infested shrub.

While the wasps themselves may be diminutive, their paper nests are not. A large nest can be a foot in diameter and composed of up to 50,000 individual cells. The paper combs and envelope are contiguous, the cells being very shallow. Honey is stored in uncapped cells, unlike in honeybee colonies where the storage cells are capped with wax. Nests, usually constructed in low trees, can be occupied for years in the tropical and subtropical climate favored by the wasps.

Brachygastra mellifica is considered to be a mostly docile species, but one would still be wise not to antagonize a nest. Dr. Joan Strassmann, Harry C. and Olga K. Wiess Professor in the Department of Ecology and Evolutionary Biology at Rice University, warns that they “….can explode, attacking en masse.” Considering that an average nest can house between 3,000 and 18,000+ worker wasps, it pays to exercise caution.

Still, the prospect of getting stung multiple times has not deterred people from exploiting these wasps since ancient times. Several references exist that document the harvesting of honey from nests of Brachygastra species (there is more than one) by indigenous peoples in Brazil and Mexico. More recently, rural peoples may transplant small nests into their yards and gardens, allowing the colonies to expand, then routing the resident wasps with smoke and destroying the combs for the honey. The wasps will re-build and start the cycle anew. You eat the honey at your own risk. Nectar collected by the wasps from plants like Jimsonweed (Datura) can translate into toxic honey.

Humans are not the only animals that covet the wasps’ cache of honey. Woodpeckers are known to break into the nests for the sweet stores of honey, and small mammals probably pilfer honey as well.

I want to thank Matthias Buck at the Royal Alberta Museum in Edmonton for identifying my images as being the species Brachygastra mellifica. There is a solitary species of vespid wasp that looks virtually identical to B. mellifica. Mexican Honey Wasps are easily distinguished by their petiolate abdomen (read “wasp waist”), but the petiole is short and nearly vertical, making it difficult to detect in live, moving specimens. Tune in next week when I’ll introduce that solitary imposter!

Sources: A great, in-depth article on the Mexican Honey Wasp can be found at the Texas Entomology website. Additional links can be obtained at the BugGuide species page.

Wasp Wednesday: More on Isodontia

Last week I showed a short video introducing you to a puzzling phenomenon in suburban areas of eastern North America. A quick review: Some homeowners in the U.S. and Canada, upon sliding open their windows, have been startled to discover the tracks filled with dry grass, dead insects, and live “worms.” Even the odd wasp has flown out. What is going on here?

Certain solitary wasps called “grass-carriers,” genus Isodontia, seem to have found window tracks make ideal nesting sites. Each female wasp makes her own nest, usually a series of cells along the length of the tunnel (though one species forms a communal brood chamber much like a bird nest).

After selecting a site, she goes in search of tree crickets or small katydids which she paralyzes with her sting and carts back to the nest. Once a cell is filled with victims, she lays an egg, and makes a partition of dry grass. Then she begins the provisioning process again, until the tunnel is filled with cells. She finishes the nest by plugging the entrance with dry grass, such that it looks as if someone has shoved a tiny broom into the hole, handle-first. Her job complete, she leaves permanently.

The larva that hatches from each egg grows by consuming the fresh prey insects. These are the “worms” that people find in the window tracks. After finishing its meals, the larva then enters the pupal stage, and an adult wasp emerges later (the following summer in northern climates).

Grass-carriers are not pests, and not aggressive towards people or pets. You will not get stung unless you physically grab a female. Males have no stinger at all.

My initial theory was that the wasps much prefer using natural cavities in dead wood, but few such natural resources exist in suburban settings. My revised theory is that the wasps may find window tracks to be a superior nesting site. Perhaps the space is “roomier” than conventional natural cavities. Maybe the parasitic flies and wasps that plague Isodontia have not yet caught on to the new nesting strategy, therefore giving Isodontia an advantage that yields more success in terms of offspring reared to maturity.

Please tolerate these wasps if you can, they are fascinating to watch. Otherwise, simply flushing the wasp and cleaning the track should discourage her from trying again.

Meanwhile, look for the adult wasps on wildflowers, especially sweetclover, sumac, and grape. They will also frequent aphid colonies, lapping up the “honeydew” secreted by the sap-sucking pests. Notice that these wasps usually have the wings splayed at rest, in contrast to other sphecid wasps that habitually fold their wings flat over their abdomen while sipping nectar.

The species shown in the images accompanying this article is Isodontia mexicana, very common over most of the eastern U.S. There are also five other species occurring in North America.

The "Bully Bee" Gets a Makeover

I like my Facebook friends. They share important bits of news with me, like a recent story about the European wool-carder bee, Anthidium manicatum. I saw this species for the first time last summer while I was in western Massachusetts. Males of this species, like the one pictured below, are indeed impressive creatures, but apparently now worthy of their killer reputation.

The complete story can be found here. Apparently the story was inspired by another story that went “viral” on the internet due to sensationalized and erroneous accounts of the wool-carder bee. My compliments go to the Reporter reporter for doing a most excellent job in researching the facts, interviewing the proper experts and communicating the right information in an understandable language. I was surprised myself to learn that the accidental introduction of A. manicatum dates back to 1963, in New York state.

We do have native species of Anthidium here in the North America, but they are not seen that often, especially in urban areas. The female A. manicatum shown below was, like the male, seen in a butterfly garden on the campus of the University of Massachusetts in Amherst last summer. She is scraping off the hairy fibers from this leaf to line one of the cells in her nest.

Please feel free to write me with links interesting news stories related to insects, spiders, and other arthropods. You can reach me at BugEric24ATyahooDOTcom. We need to reward good reporting and expose the kind of bad reporting that spreads misinformation. Thanks.

Wasp Wednesday: Audition Video

I had the privilege of auditioning for a pool of new talent with the BBC Natural History Unit back in December of 2008. They wanted a demo DVD, so I had to enlist some help. I decided I would use grass-carrier wasps of the genus Isodontia, family Sphecidae, as my subject. The result is shown below.

A huge amount of thanks goes to Kirk Sellinger of Kalypsis Productions. Kirk helped me out on a moment's notice, charged reasonable rates, and shared a few tricks of the production trade. When he isn't working with minor clients like me, Kirk joins National Geographic tours documenting both the natural history and the guests, making DVDs available to the guests at the end of the expedition.

Nothing became of this particular audition for the BBC, but they were most gracious. I would very much like to make a living interpreting insect and spider natural history through all types of media, regardless of whether I am in front of the camera or not. Watching myself in this video I might actually prefer to be behind the scenes. I welcome inquiries from those who produce nature documentaries, or referrals to production companies and others in that business.

I have appeared on television before, locally (at the "Bug Fest" at the Arkansas Museum of Discovery in Little Rock, July, 2000) nationally (a guest on Donahue in February, 1989 for a discussion on children of divorce), and syndicated (Make Peace With Nature in the 1990s). I have also performed stand-up comedy for a live audience at the end of a comedy workshop.

Since I will be out of my current part-time job come May of this year, I figure I better get started on my next move. Creative enterprises really are "my thing," and I look forward to collaborating with like minds. Oh, and I’ll be back next week with a bit more on Isodontia. Thanks.