"Is it poisonous?"

Hardly a day goes by when I am not asked some version of this question. Maybe it is phrased “Is it dangerous?” or “Is it venomous?” This illustrates just how paranoid we have become of other life forms on this planet. Let’s clarify the definition of each of these terms, and the relative risks involved with each.

Most of the time, people use the terms “poisonous” and “venomous” interchangeably. What they usually want to know whether a given spider, scorpion, or insect is venomous. Venomous animals possess toxins that they deliver to a victim by biting or stinging. Nearly all spiders are venomous, as that is how they kill their prey. Only a handful of spiders are dangerously venomous to the average, healthy human being. Here in North America, the only spiders confirmed to be potentially dangerous are widows (genus Latrodectus), and brown spiders (genus Loxosceles). This is not to say that the bite from *any* spider cannot spark an allergic reaction in someone hypersensitive to venoms.

Western Black Widow (female)

What is generally exaggerated is the risk of being bitten by a spider. The likelihood of being envenomated by a spider is quite miniscule, especially if you take simple precautions like those suggested in this article at Spiders.us.

Some venomous insects can come as a surprise to the uninformed or uninitiated. Several caterpillar species, for example, have stinging spines or hairs that can cause excruciating pain, at least in some people. Be careful not to touch hairy or spiny caterpillars.

Flannel Moth caterpillar

Ironically, tarantulas in the genus Aphonopelma will kick tiny, barbed hairs off of their abdomen instead of biting in self-defense. The hairs become airborne and, if inhaled or otherwise contact mucous membranes, cause severe irritation or even allergic reactions. Some people who handle tarantulas, or even the molted exoskeleton, may pay for the experience with contact dermatitis.

Wheel Bug adult

Many species of ants other than fire ants are capable of stinging, as can “velvet ants,” wasps in which the female gender is wingless and may resemble a large, hairy, brightly-colored ant. Assassin bugs like the Wheel Bug, and aquatic bugs like giant water bugs (aka “toe-biters”), backswimmers, and water scorpions, have a venomous bite to immobilize prey, but they can bite in self-defense, too. I can speak from experience that it is not pleasant.

Giant Centipede

Centipedes, fast-moving, snake-like arthropods with “too many legs,” are venomous, their first pair of legs modified into fangs they use to subdue their prey or defend themselves. Scorpions, arachnids related to spiders have a venomous stinger at the end of their telson (“tail”), but only the “bark scorpion,” Centruroides sculpturatus, is dangerously venomous. It occurs only in Arizona, western New Mexico, southern Nevada and Utah, and extreme southeast California.

The term poisonous means that an organism is toxic if ingested (swallowed). A startling number of insect species actually are poisonous and it pays to learn which ones, especially if you have curious toddlers prone to putting things in their mouths. Fireflies are very poisonous, as their bodies contain lucibufagins, toxins closely related to the toxins in toads.

Blister Beetle, one of many species

Blister beetles (image above) are aptly-named, for when molested they ooze a liquid substance containing cantharidin, an irritant that can raise blisters on sensitive skin. Even worse, if eaten, they can be lethal. Ranchers must be careful that blister beetles are not accidentally baled in hay. Horses that swallow beetles along with hay can die.

Millipedes, slow-moving, worm-like arthropods with lots of legs, are vegetarians, but most can defend themselves with harsh chemical secretions. Some species, like the one shown below, ooze cyanide compounds to repel potential predators. Others produce substances that can stain, or even burn, the skin.

Flat-backed Millipede

Luckily, many venomous and poisonous insects and spiders are aposematic. That is, they are marked with bright, contrasting “warning colors” such as black and yellow, orange, or white. There are many completely harmless insects that mimic those dangerous species, but when in doubt it pays to avoid handling brightly-colored animals.

While I do want people to find fascination in insects, spiders, and other invertebrates, I also want the public to stay safe and healthy. Be careful out there.

Medical Entomology Today!

I was delighted to be a presenter at the inaugural “Medical Entomology Today!” conference held in Tucson January 6-8. Organized by the Sonoran Arthropod Studies Institute, and sponsored by Rare Disease Therapeutics, Inc., it was a modest but promising success.

The Doubletree Hotel in central Tucson was the site of the conference, occupying two rooms. The registration table out front was admirably staffed by Polimana Joshevama, a gifted and energetic young lady who volunteers frequently at SASI.

Throughout the conference, one room was devote to exhibits and vendors, while the other was reserved for presentations. Shane Burchfield, representing Hatari Invertebrates and Eco Books had perhaps the most popular table, complete with live spiders, scorpions, and centipedes.

The conference kicked off Thursday evening with keynote speaker Dr. Rick Vetter of UC Riverside. His talk, entitled “The Myth of the Brown Recluse: Mythidentifications, Mythconceptions and Mythdiagnoses” was highly informative and entertaining, and free of lisps after pronunciation of the title. Rick has a great sense of humor, but he is also dedicated to achieving accuracy in the assessments of mysterious skin lesions all too often attributed to “spider bites.” Rick has documented fifty (yes, 50!) causes of necrotic wounds other than bites of recluse spiders. Some of those maladies can be far worse than a spider bite if treated incorrectly.

Friday’s morning paper sessions and afternoon workshops covered subjects as diverse as methicillin-resistant Staphylococcus aureus (MRSA) infections and their treatment through maggot therapy, to the physical and mental health effects of bed bug infestations.

Saturday morning’s papers addressed United States kissing bug species (Triatoma, pictured above) and their potential for the transmission of Chagas disease, plus an introduction to why insect stings cause pain; the development of scorpion antivenom for the stings of Centruroides sculpturatus (shown below) was another topic. The stings of this species can pose a lethal threat to infant children, but treatment with antivenom can result in a child patient being discharged from the hospital in mere hours.

Yours truly gave the final paper, “Social Media and Self-Diagnosis: How the Internet Has Changed Medical Entomology for Better and Worse.” It was an honor to present at this conference, which attracted attendees from Chicago, South Carolina, Tennessee, and New Mexico as well as Arizona.

Another great thing that came of the conference was that I got to meet Barbara Roth, wife of the late Vincent Roth, a beloved arachnologist and good friend of my mentor Jim Anderson and his wife. Barbara and I delighted in talking about our mutual friends and look forward to getting together again in the neighborhood of Portal, Arizona where she still lives and works.

Plans are already in the works for the next installment of Medical Entomology Today!, this time with the offering of continuing education credits for members of the medical community, and perhaps pest control operators as well. Please visit SASI to find proceedings of this conference as well as pending announcement of future meetings.

DustMites.org

One of the reasons my blog posts were sparse for a few weeks in May was because I was working up articles for the educational website DustMites.org. Yes, I was financially compensated for my research and writing services. Yes, the website is tied to another website for a manufacturer of dust mite mattress covers and related products. I am not promoting the products here. What I do hope is that my blog followers will point out any inaccuracies in the text, and/or give me a nudge if they hear of any new research or information pertinent to updating DustMites.org.

This project, likely to be an ongoing exercise, was quite challenging. Our collective knowledge of dust mites and their allergens is in relative infancy. One of the two most abundant and important species was only named and described in 1961. We still don’t fully understand the properties of some of the allergens, or how they act on our immune system.

There is also conflicting opinion as to the best way to alleviate asthma symptoms that are aggravated chiefly by dust mite allergens. According to one person who contacted me, rhinitis (upper respiratory system inflammation) symptoms are substantially relieved by dust mite covers on mattresses and box springs, but asthma (lower respiratory system inflammation) symptoms often persist.

A personal note: This kind of work, helping people through the dissemination of scientific information, is what I most enjoy doing. I welcome more projects like this in the future, be they related to entomology or natural history in general. Thanks for your patience during those times I am thus engaged and not as prolific in my blogging.

What bit me?!

I am often asked the seemingly simple question of “What bit me?” by folks who assume that the mere description of a skin lesion will be more than enough to determine the culprit. Aside from the fact that I face liability issues in addressing such inquiries, and can’t afford to keep an attorney on retainer, the truth is that a wide variety of agents other than insects and spiders can cause injuries that resemble “bites.”

The victim is by no means the only person who can misdiagnose the cause of a wound. Medical professionals are often guilty of doing so themselves. Beyond the obvious possibility of other causes is the victim’s own unique immune response to environmental and chemical stimuli. The virulence of insect or spider venom is, in fact, often less important than how our personal body chemistry reacts to it.

Minor itches, rashes, and swelling can be caused by something as relatively innocuous as an ingrown hair. Seriously, ingrown hairs are one of the leading causes of injuries diagnosed as “bites.” There is an excellent online article by Dr. Richard Vetter, a toxicologist at the University of California, Riverside, that documents the amazing array of agents that can cause the necrotic lesions so often attributed to the bites of brown recluse spiders.

Meanwhile, seemingly innocent creatures can pack a real wallop if handled carelessly. Among these creatures are stinging caterpillars and the non-descript blister beetles.

Still, the answer to “What bit me?” is often “nothing at all.” Please consult your physician or pediatrician to properly treat the symptoms of any wound that occurs in the absence of your own observation of the infliction of the injury. Get well soon!