Bookworms, insects and the teeth of time

Today the term bookworm has come primarily to mean a person with their nose always in a book. So I was a little surprised to learn something new about the more literal form of the word.

According to the Oxford English Dictionary the word bookworm has two meanings: (1) A person who enjoys or is devoted to reading (a "candle waster" as one 1601 writer complained); or (2)  Any of various insects that damage books; specifically a maggot that is said to burrow through paper and boards.

Surprisingly, there seems to be little agreement by non-entomologists on what kind of insects bore through books and consume the pages of history.  The larvae of wood boring beetles (anobiids) are mentioned (I've never seen this myself), as are moths, mites and booklice. Rarely does one hear about termites, though here in the U.S. our Reticulitermes flavipes has been known to partake in a good book when given the opportunity.  Indeed paper could and does make a very good bait for termites in the soil.

According to historian Stephen Greenblatt, bookworms as eaters of books have been the great fear of librarians and writers since before the Christian era. The

Illustration from Robert Hooke's 1665
book Micrographia shows a silverfish,
orabatid mite and pseudoscorpion.
Micrographia is available online for free.

silverfish is one.  In 1665 the British scientist Robert Hooke, working with one of the earliest and finest compound microscopes of his time penned the following description of a silverfish:

It is a small white Silver-shining Worm or Moth, which I found much conversant among Books and Papers, and is suppos'd to be that which corrodes and eats holes through the leaves and covers; it appears to the naked eye, a small glittering Pearl-colour'd Moth, which upon the removing of Books and Papers in the Summer, is often observ'd very nimbly to scud, and pack away to some lurking cranney, where it may the better protect itself from any appearing dangers.

If Hooke's charming anatomical description does not adhere to today's more precise terms, it still describes the silverfish reasonably well [some spellings corrected]:

Its head appears big and blunt, and its body tapers from it towards the tail, smaller and smaller, being shap'd almost like a Carrot....It had two long horns before, which were straight, and tapering towards the top, curiously ring'd or knobb'd, and bristled...the hinder part of the creature was terminated with three tails, in every particular resembling the two longer horns that grew out of the head

Later, he refers to silverfish (and other paper chewers) as representing the "teeth of Time", appropriate considering how much of history has been literally swallowed up by the silverfish and its ilk.

Silverfish are among the most primitive of the hexapods. Belonging to the insect order Thysanura, springtails and their cousins the firebrats are probably less known to most PMPs than, say cockroaches or ants.  Yet they are among the most common structural pests, especially in older structures. Unlike true insects, they do not go through metamorphosis and never seem to stop molting, even after reaching the adult stage. Instead, the nymphs look like miniature versions of the adults. Silverfish are roamers, and will travel throughout a structure to find food.  Once found though, they tend to stay close to their food source.

So on what do silverfish feed?  They seem to especially like paper that has been treated or coated with edible substances like starch, dextrin, casein, gum, and glue. Many of these materials are added to paper to influence its ability to absorb water or ink.  Glues used in books are also often natural in origin, and apparently tasty to silverfish.  But silverfish also digest cellulose, as shown experimentally by their preference for onion skin and cellophane (almost pure cellulose).  The well-known (to PMPs) entomologist Arnold Mallis showed that newsprint and cardboard and brown wrapping paper is almost never eaten by silverfish. They will feed on plant textiles like linens, cotton and lisle, however silk or wool is rarely eaten.

The Mallis Handbook notes that silverfish can be one of the more difficult pests to control, and elimination from a structure is not likely, short of fumigation.  This is largely because silverfish are able to hide throughout a structure in all its nooks and "cranneys"--as Hooke described them. It is certainly difficult, if not impossible, to treat all the hiding places of silverfish in a house. Desiccants applied to cracks and crevices where silverfish hide can be effective.  According to Frank Meek in the Mallis Handbook, silverfish are difficult to control using baits, though there may be limited value in applying some of the fine granular baits labeled for silverfish control.  Reducing humidity, vacuuming, sealing up valuable items, removing known food sources, and use of sticky traps are also listed as non-chemical controls for silverfish.

I have to admit that I have little practical experience with silverfish, except perhaps the few in my own office where they seem to relish small amounts of spilled cricket bait around my tarantula cage (crickets feed the tarantula). But now that I think of it, perhaps I had better spend more time considering how to discourage these critters before they devour some of my favorite books.

As Greenblatt noted, the ancients realized the battle against bookworms would be never-ending, and the best solution was to read the books (or parchments) regularly, and plan on replacing them when they inevitably decay. Of course your customers may not be happy with that, so its up to you to solve the puzzle of the bookworm 350 years after Robert Hooke first trained his microscope on the "silver-shining worms".

Acknowledgement to Stephen Greenblatt and his book: The Swerve: How the World Became Modern, for the inspiration for this post.

Wild for insect photography

Alex Wild face-to-face shot of a bed bug.  This image and
many more are available at www.alexanderwild.com 

Last week renowned insect photographer Alex Wild gave a webinar (web delivered speech) on insect photography for Entomological Society of America members.  Many of you in pest control land have likely seen some of Alex's ubiquitous pictures in industry brochures and magazines.  He especially seems to get lots of use out of the many pictures he's taken of insects on bright white backgrounds.

If you have any interest in insect or macrophotography you will probably get a lot out of this hour-long video. If you're thinking you don't have a good enough camera to get into insect photography, the talk focuses on five principles that will help anyone with any digital camera, including a cell phone.  The principles include:

• Keep it simple
• Consider the light
• The Center's not the Center
• Tell a Story with your lens position
• Patience is a virtue

And lastly, something I really appreciate, he talks about dealing with insects as uncooperative subjects.  I've often envied my horticulture and weed specialist colleagues whose subjects don't run when the camera emerges. Alex shares a few tips that will help you tame those frisky insects prior to taking the shot.

All in all, a worthwhile way to spend an hour.

Just a plug for Alexander Wild Photography, by the way. Alex does sell his images for commercial use, so if you are looking for a particular insect picture for an ad or web page, go to http://www.alexanderwild.com

Talking about pesticide risk

How many times have you been asked some variation of the question, "How toxic is that pesticide?" Maybe it's been in the form of a statement from a new customer: "I'm expecting," or "I'm chemically sensitive."  Or perhaps you've heard, "Will your spray hurt my puppy?"

How we answer that question says a lot about our credibility and our professionalism.  So it might just pay to think about some of the better ways to talk about pesticide risk. I'm not an expert in risk communication, but I've had the opportunity to talk with lots of people about pesticides.  And I find that most people are a lot more accepting of pesticides as tools if they are approached properly and with an olive branch rather than a stick.

Of course, if people made decisions about risk based on logic and reasoning, we could answer questions about pesticide risk with facts and figures.  But experts in the field of risk perception tell us that when it comes to assessing risk none of us are very rational. Hence we fret over the threat of catching Ebola in America (1: 13.3 million), but don't worry daily about being in a car accident (1: 9,100 chance this year).  For this reason, I know we won't convince everyone to hire a pest control company tomorrow, but I believe with the right approach, we can offer consumers a little peace of mind about their pest control service.

Here are a few suggestions for talking with potential customers about pesticide risk:

• Show your customer you care. Let them know you are concerned about their safety and make every effort to keep indoor pesticide use to a minimum through the use of IPM (assuming this is true!). Assure your customer that you use only those pesticides that are necessary to do the job you're being asked to do. 
• Avoid use of the word “safe”. There is no guarantee of absolute safety for any pesticide, or drug--or any activity we do, for that matter. Instead use the concept of risk. We can guarantee a level of risk, if we can never guarantee absolute safety (a one in a million risk is not absolutely “safe”). Although the EPA does not “approve” pesticides, it will not register a pesticide unless it's persuaded that there is no unreasonable risk of adverse effects associated with its label uses. 
• Pet peeve: Avoid comparing the toxicity of pesticides to food items like table salt. While it's true that table salt has toxicity, and some insecticide LD50 values show less toxicity than table salt, most people don’t buy it. After all, we produce salt to be ingested. Insecticides are produced to kill stuff. Its apples and oranges--not a fair comparison. When comparing toxicity, compare your products to another pesticide or consumer product that the customer already uses. For example, many pets are treated by vets for fleas with the same active ingredients used in household pest control. If they have already accepted the risk in applying a product to their pets, then it’s not unreasonable to propose use of the same product outdoors or in protected crevices of the home with even less exposure. 
• Let your customer know that you are concerned about the risk of working with pesticides, because your exposure risk is so much higher than theirs. This sort of explanation is especially helpful because we base many personal decisions on the experiences of friends and acquaintances. Your confidence in your ability to work safely with pesticides is a powerful witness to those you meet.

For potential customers who believe they are sensitive to chemicals, especially pesticides, you may need a slightly different approach. Ironically, these folks often need to be talked out of using pesticides. What I mean is that even chemically sensitive clients think they need an "organic" pesticide or repellent, to get rid of their pests. Even though they are chemical averse, they are still of the idea that there is a chemical (albeit natural) out there to control their pest problem.

Often these callers haven't considered the possibility that there might be a non-chemical solution to their pest problem. This is where knowing your pests comes in. You might be able to offer some environmental modifications, pest proofing or biological control options that can moderate or lessen the pest problem sufficiently.  Or you might be able to confine treatments to outdoor areas.  Or they might consider baits (termites, ants, some other crawling insects) as non-volatile, hypoallergenic alternatives to sprays, dusts or aerosols.

This month it might be worth a little time talking with your staff about how to better talk about pesticide risks. Your sincerity, along with that olive branch, can go a long way toward making that customer with pesticide concerns a customer for life.

Flag waving for Americans

I never get tired of reminding PMPs that professionalism starts with good identification skills. One insect that is just rare enough to puzzle most pest control technicians is the ensign wasp.  It is also one of the odder insects found in homes and businesses.

The ensign wasp, Evania appendigaster may be one of the
oddest  looking insects in pest control. Its name comes from
the flag-shaped abdomen that it waves while searching
for its cockroach prey.

The ensign wasp is a quick and nervous little insect.  Black and 5-7 mm long, it is usually found one at a time. Though it might look intimidating with its quick actions and an abdomen bobbing up and down, it does not sting or bite.  It is, in fact, a beneficial parasite that helps control at least three household cockroaches, the American cockroach being the most common.

Ensign wasps are cockroach egg parasites. They are experts at locating cockroach egg cases (oothecae).  According to one account, when the female ensign wasp encounters a cockroach egg case, she first taps it with her antennae, presumably to confirm that it is an acceptable host for her egg.  Then she lies down beside it (I have never heard of an insect voluntarily lying on its side before!) and braces her legs against the ootheca.  After much labor she inserts her slender ovipositor into the tough ootheca and lays a single egg.  After hatching, the wasp larva matures while feeding on the dozen or more cockroach eggs inside each ootheca.  No cockroaches will hatch from an egg case that has been parasitized by an ensign wasp.

The name ensign wasp comes from the unique, stalked abdomen.  Shaped like a sailor's signal flag, the wasp frequently waves her abdomen up and down while stalking her prey as if to say, "Here I am!  Look out cockroaches!"

The oothecae of  American cockroaches are glued in out of
the way locations in walls, attics and other places. A single
egg inserted by an ensign wasp inside the ootheca will prevent
hatching.  Bugwood photo by Gary Alpert, Harvard Univ.

So what does it mean finding an ensign wasp in an account?  It means cockroaches are around. Not just any cockroaches, but one of the larger species of cockroaches (American, Smoky brown, or Oriental cockroaches).  I see one or two of these wasps in my office building every year.  I know they come from the rarely seen population of American cockroaches lurking in the walls and ceilings of our office building--something found in nearly every commercial building.  I like to think that we don't see a lot of cockroaches because we have these little wasps keeping watch.

Nevertheless if you or your customer are seeing these wasps on a regular basis, it might mean there are more cockroaches around than you suspect. Check the crawl space, attic and utility areas.  Make sure that p-traps in the floor drains are being filled with water on a regular basis.  Consider setting out sticky traps and baiting suspected harborage areas such as garages, attics, pantries or utility rooms.

If you are looking for more information to provide your customers about cockroach control, check out the Extension fact sheet Cockroaches and Their Control.

Concrete mites

Mites are among the tiniest arthropod pests to challenge the pest management professional. Tiny relatives of ticks (Class Acarina), mites play many roles in their microscopic world.  Some are predators of insects, insect eggs or other mites. Others are plant feeders, weakening plants and spreading disease.  Some mites feed exclusively on decaying plant material.  And still others are parasites, hitching rides on spiders or beetles, feeding on birds and mammals and even humans.

Insects are hard enough to identify because of their small size. But most insects are huge compared to mites. Larger mites may reach 1-2 mm in length; most are much smaller.  Scabies mite, one of the only mite parasites to exclusively feed on humans, are among the smallest of mites (0.18-0.45 mm-long) and visible only through magnification. Most mites are less than 1 mm-long, though velvet mites (the largest of the mites) can reach lengths of 4 mm, as long as a termite worker.

Clover mites are distinguished by their long front legs. Photo
by Rayanne Lehman.

For size reasons, I'll admit that I groan a little inwardly when I receive a mite specimen to identify. Mounting mites on glass slides is not one of my strong skills, and takes extra time.  So I was pleasantly surprised this week when a promised mite sample arrived and it was actually on the big size, at least for a mite.

I was initially ready to identify my client's mite as a clover mite, one of the common springtime mite pests in Texas. The clover mite, Bryobia praetiosa, is a reddish brown mite with very long pair of front legs, about 2X the length of the other legs. Though mostly harmless, the clover mite is an occasional nuisance pest indoors when it migrates from its normal feeding sites in grass and weeds outdoors through windows and under doors.  But there was something about these mites that didn't quite fit the clover mite profile.  

Balaustium (or concrete) mite. Photograph
by Lyle J. Buss, University of Florida

The one-millimeter-long, bright red mites were being found all over decorative stone and concrete in a Tyler, Texas backyard.  The homeowner thought he was being bitten, perhaps by mutant chiggers from you-know-where. But although chigger mites are also bright red, they are tiny (.3 mm) and barely visible to the naked eye. These were not chiggers.

An online search led me to one of my favorite online resources, Bugguide.net. There I discovered a mite genus I had never heard of before.  Concrete mites, Balaustium species, were a dead ringer for the specimens I had under the microscope.  So called, because certain species in this genus are commonly found wandering on concrete sidewalks, foundations and walls, and stonework, Balaustium mites are apparently common throughout the U.S.; but I had never heard of them before.

The University of Florida Entomology Circular Series (also an excellent source of detailed information about urban insects, especially plant-feeding pests) had a 1995 publication by W. C. Welbourn on Balaustium mites in Florida. According to the circular, at least one species of Balaustium is "commonly found in urban areas where they appear in large numbers on sidewalks and walls for a brief period during the spring and early summer. It is during this time that they sometimes enter homes and buildings and become pests."  

One of, if not the only, food source of these urban mites appears to be pollen. Balaustium mites have been found clustered in large numbers on anthers of flowers.  And based on the numbers of times I've had to wash my car and BBQ grill of oak pollen in the past month, I'm imaging that these mites have been having a good time of it lately.  This would also explain why the mites can be found on nearly any outdoor surface, including sidewalks and roofs--because pollen is everywhere.

Some species of Balaustium are predators on other insects, others feed on plants.  I was surprised, however, to read that there may be some association between our otherwise peaceful, pollen feeding, house-invading concrete mites and bites on people.  An entomologist named Irwin Newell in 1963 reported four cases of human "biting" involving Balaustium, three of which were associated with structures. The evidence for the bites was very strong, including a sample submitted by entomologist who was bitten on the arm while working in an entomology museum (how dare they!). 

The curious thing about the story is that while Dr. Newell stumbled across several cases in a relatively short period of time, prompting him to predict this mite was a growing problem, it's been crickets (silence) since then.  None of the major texts or reference books I scanned have even a mention of this family of mites, in spite of being common in the landscape. Even Ed Riley, Texas A&M University's crack assistant museum curator, was not familiar with these mites--though he admits, like me, to not paying too close attention to red mites he sees outdoors.  

Newell admits in his paper that he had no idea what species of Balaustium he was dealing with in his biting cases. And I don't believe anyone know what species are common in Texas. But I will be more interested and paying closer attention the next time I see my brick mailbox covered with red mites. 

[Request: I have little doubt that some of you get questions from customers about little red mites crawling on the sides of homes and sidewalks this time of year.  I would be interested to know if you or anyone you meet believes they have experienced bites from these little critters.]