Laboratory and Field Evaluations of Food Based Attractants for Monitoring German Cockroaches

This work described below was performed at Rutgers University in Changlu Wang’s lab and was published in the Journal of Economic Entomology.

In this study, the researchers were interested in identifying effective, relatively inexpensive, readily available attractants for German cockroaches. As you know, sticky traps are the workhorse of IPM and are widely used across the industry to monitor many different urban pests in a wide range of accounts. Unfortunately, sticky traps without an attractant/lure/bait only catch cockroaches when the pests happen to wander onto the trap and become stuck. Of course, trap placement can maximize the probability of cockroach encounters, but catch rates are still dependent on chance. There are commercial lures available, but the authors were looking for cost-conscious alternatives that really worked.

One of the classic cockroach attractants that you will find in the old school textbooks is the use of stale beer and bread, placed inside a mason jar as a cockroach trap. With the prospects of learning about the hijinks that ensued at the Rutgers Urban Entomology lab while testing beers on cockroaches, I eagerly dug into this paper. But to my dismay, the researchers did not test beer styles as attractants. They did test 18 different attractants – including things like fish, blueberry, sugar cookie and root beer oils, synthetic German cockroach pheromones, peanut butter, and cumin seed oil. (Learn more about some undergraduate research at Texas A&M on cockroach beer preferences here.)

Curiosity got the best of me and I followed a rabbit trail to learn the source of their oil supplier. It turns out that you can find fragrance oils for more than 140 different smells on the manufacturer’s website – things like: baby powder, birthday cake and churros.  In fact, in the description for bacon extract oil it stated that it could be used as cologne. But I digress.

Essentially, what they did at Rutgers was place 500 cockroaches into an experimental arena, introduced 4 sticky traps into each, and after 2 days compared the number of cockroaches caught on the traps containing attractants with those that didn’t. The attractants were placed cotton wicks that were placed inside a centrifuge micro tube (1.5 mL).   They also performed head-to-head tests between attractants.

Here’s what they learned: Sticky traps containing apple oil, blueberry oil, orange oil (or their combinations), fish oil, peanut butter, commercial roach lure tablets or bacon extract had significantly higher catch rates than an un-baited traps.

Now, understand that these are laboratory results (with no competing food sources) so the researchers put the most promising attractants to the test in the field inside affordable housing apartments in Jersey City and Linden, NJ.  They learned that on average, the combination of apple + blueberry oil, and the commercial roach lure tablet increased trap catch in infested apartments by 103% and bacon extract increased catch rates by 92%.

They did state that more research needs to be performed to determined accurate and reliable delivery methods for the attractants, but the bottom line is this: if you want to increase German cockroach catch rates in sticky traps – use commercially available roach lure tablets or combinations of apple + blueberry oil. Those perform best. But if you want to catch me in a sticky trap, try the bacon.

Jim Fredericks, PhD, BCE


Salehe Abbar, Changlu Wang, Laboratory and Field Evaluations of Food-Based Attractants for Monitoring German Cockroaches, Journal of Economic Entomology, Volume 114, Issue 4, August 2021, Pages 1758–1763,

Test Your Identification Skills With the Termite Teeth Challenge!

Ph.D Candidate and student researcher at the University of Georgia, Allison Johnson, is in need of some help to compare expert identifications of termite teeth to your best identification guesses. Allison works with Dr. Brian Forschler at UGA and they do some really cool work – check out more here I took the challenge and was pleasantly surprised at the end to see my results and it wasn’t half bad! If you’ve got a few short minutes, download and follow the instructions below to get started – it’s basically like an advanced matching game with termite teeth!

Brittany Campbell, PhD, BCE

Determining the Best Placement for Rodent Devices at Commercial Food Buildings

Rodent devices at food facilities are typically spaced according to the standards of an auditing body, or a company’s standard operating procedures, or because “that’s just the way we’ve always done it.” Indoors, traps are usually 20-40 feet apart and exterior stations are spaced 50 to 100 feet apart. But, have you ever thought about why we do this spacing and if it’s really the best way to determine where to put your traps or bait stations?

The conventional interval spacing, described above, was established in the 1940s and 50s based on the range that rodents forage for food. Yet, there isn’t a ton of scientific evidence behind this spacing and it also fails to take any other aspect of rodent behavior or conducive conditions into account. So, a recent study investigated this conventional, standard interval trap placement to determine if there are specific building characteristics or rodent behaviors that may influence or enhance trap catches and/or bait consumption.

The researchers evaluated seven food warehouse distribution centers in New York, USA and 5 in Ontario, Canada. Passive multi-catch traps were used indoors and mouse and bait stations with rodenticide were placed outside. All facilities utilized the standard spacing of traps in the interior and then researchers noted characteristics of the building like construction and ecological conditions that would be attractive to rodents. Some examples include the dock door not having a compression seal or the bottom of the door not being rodent proof, if the device was near a product aisle, a heater source, in a drop ceiling etc., with a total of 76 characteristics used to evaluate indoor traps and 27 characteristics outdoors.

The researchers discovered that about half, (45%) of interior devices captured mice and 56% of exterior bait stations had some evidence of rodent feeding. Not surprisingly, certain structural characteristics or conditions resulted in more trap catches or higher feeding in bait stations. Characteristics that resulted in higher activity included areas with warmer temperatures, along pathways, near concrete walls, on the edges or corners of walls, near dense vegetation and in shadows. Basically, warmer areas with more cover and protection should alert someone to spend more time for inspection and be a focal point for device placement.

Moving forward, this research lends to a more assessment-based approach, where an inspection is conducted first to determine the areas that have higher rodent activity and then trap placement based on the assessment of a facility, rather than arbitrary distances. Additionally, this could result in a reduction of rodenticide waste. Almost 40% of bait blocks that were evaluated had no feeding and would have been thrown away. With a more assessment-based approach, some of the stations that were not visited could be moved in areas that will receive activity and eliminate the use of bait that isn’t necessary.

If you want more details, you can read the paper here:

Frye, M. J., Gangloff-Kaufmann, J. L., Corrigan, R. M., Hirsch, H., & Bondy, D. (2021). Assessment of factors influencing visitation to rodent management devices at food distribution centers. Journal of Stored Products Research93, 101838.

Non-Chemical Bed Bug Management

Bed bugs are one of the most labor-intensive pests that pest management professionals (PMPs) tackle. These tiny, cryptic (i.e. well hidden) creatures can get into almost anything inside of human spaces and are keenly adept at spreading by themselves or hitching a ride. Often, digging into the PMP toolbox and utilizing a combination of tools is necessary to get complete control of bed bug infestations. Aside from pesticides, there are multiple non-chemical options that can be used in conjunction with other treatment methods for bed bug control. Non-chemical essentially means anything that doesn’t require a pesticide like vacuuming, mattress encasements, steam, and heat for bed bug control.

Recent research out of Rutger’s Entomology Department evaluated the effectiveness of some non-chemical management strategies against bed bugs. They compared two different non-chemical programs in three different high-rise buildings in New Jersey, two managed by a private company and one by a public housing authority. The buildings had 7 years of bed bug infestation history with documented self-treating, treatments by housing staff and some PMP interventions. For one program, the researchers steamed furniture, vacuumed, installed mattress encasements, installed pitfall traps, asked clients to wash bedding and provided brochures for client education. In the second program, they did all of the same non-chemical options but also added silica dust applications to furniture and baseboards.

The non-chemical methods alone completely eliminated bed bugs in 36% of the apartments and reduced the total number of bed bugs by 89%. In the non-chemical program plus silica dust, bed bugs were completely eliminated in 40% of apartments and there was an overall reduction of 99% of bed bugs. The bed bug numbers declined more quickly with the addition of silica dust. In apartments with low levels of bed bugs, the researchers found it was possible to eliminate bed bugs using only the non-chemical methods. However, client communication is always key, and the researchers hit a few snags with residents. In one apartment, the resident refused to accept they still had bed bugs and removed the encasement from their bed. While significant reduction (98%) of bed bugs did happen in this apartment, complete eradication required the cooperation of the client. Sometimes the hardest aspect of pest control is not the insects, but rather finding a way to better communicate with clients to encourage cooperation.

Brittany Campbell, PhD, BCE


Abbar, S., Wang, C., & Cooper, R. (2020). Evaluation of a non-chemical compared to a non-chemical plus silica gel approach to bed bug management. Insects11(7), 443.

How Humidity Levels Impact the Most Common Pest No One Knows They Have

Psocids are a group of insects containing about 5,500 species that are commonly referred to as barklice and booklice. Despite the fact that psocids do not bite, research performed in the last 20 years has shown that parasitic lice, like head and body lice, actually share a common ancestor with booklice and therefore should be lumped into the same order called Psocodea.

Psocids are important pests in stored grains, where they can result in contamination, damage, and possible rejection of commodities. They can also be a concern in warehouses, museums and even homes. Book lice are actually one of the most ubiquitous pests that no one knows is present in their homes.  A few years ago, a research team at North Carolina State University investigated which arthropods were most commonly found in homes in North Carolina.  Out of the nearly 200 homes inspected, nearly every single one had booklice present.

Since these pests are so small, they are often overlooked. But in recent years, commercial control in grain storage has become more difficult since some populations have developed resistance to certain pesticides, including some fumigants like methyl bromide and phosphine. It is known that psocid infestations often occur in locations where moisture is an issue. New research at Oklahoma State University sought to determine what humidity levels are required to kill psocids. 

This research was performed by Abena Ocran and her colleagues and was published in the Journal of Economic Entomology in April 2021. The researchers exposed all life stages (eggs, nymphs and adults) of four different psocid species to 43, 50, or 75% relative humidity at a constant temperature of 30 degrees Celsius (86 degree F) for different time periods. 

Here’s what they learned:

  • All of the psocids kept at 75% RH increased in population size after 14 days.
  • Lower humidity levels were lethal to psocids
  • Eggs were a little bit more tolerant than nymphs and adults, but all life stages of all four species were killed after 16 days at 50% RH.

One of the most common recommendations that PMPs make to clients with psocid infestations is to lower humidity levels, so this research lends credence to that common recommendation and provides more data to help set customer expectations. That is, your customer should expect to see control 16 days after lowering the humidity below 50%. Additionally, this information can also be used in grain storage facilities to help supplement pest control efforts through IPM approaches. By understanding and communicating information such as this, PMPs can deliver data driven recommendations for clients that will help manage expectations and control one of the most common pests in homes.

Jim Fredericks, PhD, BCE


Bertone MA, Leong M, Bayless KM, Malow TLF, Dunn RR, Trautwein MD. 2016. Arthropods of the great indoors: characterizing diversity inside urban and suburban homes. PeerJ 4:e1582

Abena F Ocran, George P Opit, Bruce H Noden, Frank H Arthur, Bradford M Kard, Effects of Dehumidification on the Survivorship of Four Psocid Species, Journal of Economic Entomology, 2021;, toab066,

Susceptibility of Midge and Mosquito Vectors to SARS-CoV-2

Severe acute respiratory syndrome coronavirus 2, also known as SARS-CoV-2, is the notorious coronavirus responsible for the COVID-19 pandemic. As is the case with any disease, understanding how SARS-CoV-2 spreads through a population is one of the most important steps in slowing transmission. Early on, scientists determined that the primary mode of infection for SARS-CoV-2 is through exposure to respiratory droplets carrying infectious virus (CDC 2021). This means the most likely route of infection would be through direct, indirect, or close contact (<6 feet) of an infected person through infected secretions.

In 2020, scientists published findings that SARS-CoV-2 viral RNA (genetic material of the virus) was identified in the blood and serum of infected patients, suggesting that the virus could also be present in the bloodstream (Chen et al. 2020, Hogan et al. 2020, Young et al. 2020). This led researchers to question if blood-sucking arthropods like biting flies could also serve as a mode of biological transmission for SARS-CoV-2. Initial experiments testing this hypothesis confirmed that the virus did not replicate in three common mosquito species (Aedes aegypti, Ae. albopictus, and Culex quinquefasciatus) after the virus was injected directly into the mosquitoes (Huang et al. 2020). Additional research by Xai et al. (2020) showed that the virus did not replicate in cells collected from Aedes mosquitoes, and SARS-CoV-2 was never recovered from field-caught Culex or Aedes mosquitoes from Wuhan. These results were promising, but only a few species were tested, and researchers injected the mosquitoes with the virus rather than allowing them to ingest an infected bloodmeal. 

Balaraman et al. (2021) set out to address some of the holes left in previous research by testing if more species of biting flies were susceptible to the SARS-CoV-2 virus after ingesting an infected blood meal. The research team expanded on the list of biting insects investigated to include two previously untested flies, a biting midge (Culicoides sonorensis) and another species of Culex mosquito (Cx. Tarsalis), along with the previously tested Culex species Cx. quinquefasciatus.

To get a better idea of susceptibility of these insects to the virus, the research team measured the infection potential of these biting insects in two different ways. First, cultured cells from all three species were exposed to SARS-CoV-2 to determine if the cells from any species were vulnerable to infection or damage. Results from these experiments were negative for all insects, meaning they showed no signs of cellular infection or damage.

The next step was to test if any of the three species would be susceptible to infection after ingesting an infected bloodmeal. Researchers fed the insects on blood spiked with SARS-CoV-2 and held them for 10 days. After the waiting period, all blood-fed insects were tested for the presence of SARS-CoV-2 viral RNA and positive samples were set aside for further evaluation. It is important to note here that viral RNA is not the same as infectious virus. This means that simply confirming the presence of viral RNA would not also guarantee that infectious virus particles were present. To determine if any of the samples with viral RNA also contained infectious virus, another set of experiments were conducted that measured cellular damage to confirm viral infection. Those results were all negative meaning that none of the samples tested positive for infectious virus. 

It may seem like a no-brainer that the mosquito, an insect crowned the world’s deadliest organism because of the diseases it is known to spread, should also be able to biologically transmit the SARS-CoV-2 virus. But the disease transmission process can be extremely complicated. The overarching conclusion we can draw from these studies is that the biting insects studied so far most likely do not play a role in biological transmission of SARS-CoV-2. While we cannot rule out the possibility of arthropod-borne transmission of SARS-CoV-2 all together, there is no evidence so far to suggest this route of transmission is possible.

Research is currently ongoing to measure the potential for some insects (mostly cockroaches and flies) to mechanically spread the SARS-CoV-2 virus after contacting a contaminated surface or material. While this route of viral spread may be more plausible, the likelihood that a person contracts COVID-19 after contacting a contaminated surface is low CDC (2021).

Mike Bentley, PhD, BCE


Centers for Disease Control and Prevention. (2020). Science Brief: SARS-CoV-2 and Potential Airborne Transmission.

Centers for Disease Control and Prevention. (2021). Science Brief: SARS-CoV-2 and Surface (Fomite) Transmission for Indoor Community Environments.

Chen, W., Y.  Lan, X.  Yuan, X.  Deng, Y.  Li, X.  Cai, L.  Li, R.  He, Y.  Tan, X.  Deng, . et al.  2020. Detectable 2019-nCoV viral RNA in blood is a strong indicator for the further clinical severity. Emerg. Microbes Infect. 9: 469–473.

Huang, Y. J. S., D.L.  Vanlandingham, A.N.  Bilyeu, H.M.  Sharp, S.M.  Hettenbach, and S.  Higgs. . 2020. SARS-CoV-2 failure to infect or replicate in mosquitoes: an extreme challenge. Sci. Rep. 10: 1–4. 

Hogan, C. A., B. A.  Stevens, M. K.  Sahoo, C.  Huang, N.  Garamani, S.  Gombar, F.  Yamamoto, K.  Murugesan, J.  Kurzer, J.  Zehnder, . et al.  2020. High frequency of SARS-CoV-2 RNAemia and association with severe disease. Clin. Infect. Dis. 1–5. 

World Health Organization. (2021). Malaria.

Xia, H., E.  Atoni, L.  Zhao, N.  Ren, D.  Huang, R.  Pei, Z.  Chen, J.  Xiong, R.  Nyaruaba, S.  Xiao, . et al.  2020. SARS-CoV-2 does not replicate in Aedes mosquito cells nor present in field-caught mosquitoes from Wuhan. Virol. Sin. 35: 355–358. 

Young, B. E., S. W. X.  Ong, S.  Kalimuddin, J. G.  Low, S. Y.  Tan, J.  Loh, O. T.  Ng, K.  Marimuthu, L. W.  Ang, T. M.  Mak, . et al.; Singapore 2019 Novel Coronavirus Outbreak Research Team. 2020. Epidemiologic features and clinical course of patients infected with SARS-CoV-2 in Singapore. JAMA  323: 1488–1494.

Finding Ways to Reduce the Risk of Non-Target Rodenticide Exposure in Roof Rat Control

Earlier this month, a research paper was published in the journal Pest Management Science titled “Use of Rodenticide Bait Stations by Commensal Rodents at the Urban-Wildland Interface: Insights for Management to Reduce Non-Target Exposure”. This research was partially funded by a Pest Management Foundation grant made to Dr. Niamh Quinn’s research program at University of California Agriculture and Natural Resources, South Coast Research and Extension Center in Irvine California. The Pest Management Foundation is an independent non-profit charity that provides scholarships for outstanding urban entomology students and funds structural pest control research at universities across the United States. All of the Foundation’s work is made possible by donations from pest control companies and individuals interested in advancing the science of structural pest control.

In recent years, anti-pesticide groups have placed pressure on pest management professionals regarding non-target exposures of wildlife to anticoagulant rodenticides – especially in California mountain lions, birds of prey in New England, and most recently in bobcat populations on Kiawah Island, South Carolina. The knee jerk reaction by many of these activist groups has been to ban the use of these products based on residue data that may show sub-lethal amounts of anticoagulants in non-targets. In California, a measure was successfully passed in December 2020 to ban most SGAR uses across the state, even by licensed professionals. Unfortunately, outright bans like these don’t take into consideration the important beneficial role that rodenticides play in managing these important public health pests and that instead of banning the products altogether, it’s important to first understand how non-targets are becoming exposed, then try to limit those exposures through common sense risk mitigation.

Although it is not known exactly how these non-target exposures are occurring, it is thought that native rodents like deer mice, wood rats, kangaroo rats and ground squirrels are likely entering stations and consuming rodenticide bait, then raptors, coyotes, pumas or other non-target predators are eating the non-target, non-pest, native rodents.

To better understand which native rodents are entering bait stations, Dr. Quinn and her colleagues, positioned two bait stations in more than 90 backyards in southern California.  One station was placed at ground level and one was positioned 3-5 feet off the ground.  Non-toxic commercial bait was placed inside each station, then digital cameras were focused on the two bait stations and every animal that interacted or entered the bait station was photographed.  More than half a million photos were captured during the study and here’s what was learned: 

  • Roof rats were present at more than 80% of the sites. House mice and Norway rats were observed much less commonly.
  • Native rodents (deer mice, wood rats, kangaroo rats and ground squirrels) were relatively rare, visiting or entering bait stations at only 13% of the sites. 
  • Native rodents were five times less likely to enter the stations that were positioned off the ground.
  • Roof rats, on the other hand, were equally likely to find, enter and interact with bait stations when positioned off the ground.

The authors made four specific pest management recommendations based on this research:

  1. PMPs should monitor bait consumption closely during the first few weeks to ensure that adequate bait is available to control populations.  High populations of rats can deplete baits quickly.
  2. On average it took roof rats 7-8 days to enter a station.  SGAR baits typically take 3-5 days to work, so control effects may not be seen for as long as two weeks after application.  This should be communicated to clients so that expectations can be managed.
  3. In areas where predator species like coyotes are common (that is, homes closer to natural areas and parks) care should be taken to clean up any rat carcasses that are found in the open.
  4. When roof rats are the target pest, positioning bait stations 3-5 feet off the ground can limit non target entry into the stations. 

Jim Fredericks, PhD, BCE

To read the full research paper visit:

To learn more about the other research projects taking place in Dr. Quinn’s lab visit

To learn more about the kinds of research that the Pest Management Foundation funds, or to make a donation, visit .

Dung Beetles as Vertebrate Samplers

A biodiversity survey is an important tool that scientists use to gain a baseline understanding of organisms in an ecosystem. These surveys record the abundance (how many) and/or diversity (variety of animals) of species in the environment so scientists can monitor any change over time. The data collected from these surveys are the cornerstone to conservation research because collecting this data tells us which habitats and animals are being negatively affected and require protection efforts.

One challenge with biodiversity surveys is that the traditional sampling methods used to collect data are largely dependent on visual counts that are inherently biased. For example, a survey wanting to track the number of birds in a habitat may be limited by the researcher’s ability to visually spot and correctly identify that particular species. This is especially challenging when the target organism is rare or difficult to spot.

To address this challenge, scientists developed a new technique for large-scale biodiversity monitoring known as environmental DNA surveillance (Figure 1). Environmental DNA (or eDNA) is genetic material collected directly from environmental samples such as soil or water. Using this technique, scientists can identify the DNA of several organisms that have contacted the sample, offering a less-biased surveillance tool that is ideal for counting elusive or rare organisms. While this technique has its obvious advantages over traditional methods, one drawback is that water tends to be better than soil at preserving DNA which means aquatic environments are easier to survey than terrestrial habitats.

Figure 1. The overall workflow for environmental DNA (eDNA) studies with examples of organisms that have been identified from environmental samples. Image Credit:

Previous studies have investigated the use of blood-feeding invertebrates such as flies, leaches, and mosquitoes as alternative sources of eDNA, referred to as invertebrate-derived DNA (iDNA), to survey land-based animals (Beng et al. 2016, Robson et al. 2016, Nguyen et al. 2020). However, these organisms are often difficult to collect, limiting their use in large-scale surveillance programs.

Dung beetles are a widely distributed group of detritivores that feed on the fecal matter of terrestrial animals. Earlier experiments showed that certain cells found in mammal dung and ingested by dung beetles could be used as a source of identifiable DNA (Gómez & Kolokotronis 2016, Kerley et al. 2018). Since dung beetles are easy to collect in large numbers and are widely distributed, and a method for iDNA detection was already identified, this gave dung beetles an advantage over other invertebrates for their potential use in iDNA surveillance.

To further investigate the use of dung beetles as iDNA samplers, Drinkwater et al. (2021) set out to address two questions. How long could mammal DNA remain viable for identification in the gut of one dung beetle species (Catharsius renaudpauliani), and would it be possible to identify the DNA of multiple mammal species from the gut contents of several dung beetles? To address the first question, researchers fed 60 C. renaudpauliani on cow dung, then analyzed the gut contents of selected individuals at set time intervals ranging from 0 to 56 hours. They found that sufficient DNA could be recovered up to 4 hours after feeding, but the amount of DNA recovered dropped to zero at 9 hours post feeding. This meant that mammal DNA could be preserved long enough in wild dung beetles to be identified. And, the animal DNA that was identified from these dung beetles would have been from dung consumed within a short period of time before the beetles were caught. To address the second question, Drinkwater et al. (2021) trapped dung beetles in the field and evaluated their gut contents for mammalian DNA. They were able to confirm DNA of six different mammalian taxa, with three being identified down to species.

Collectively, these findings showed that dung beetles could serve as an easy to collect and widely distributed source of iDNA. This study takes us one step closer to better understanding a new source of invertebrate DNA in the quest for improved sampling methods. It’s the steppingstones of scientific discovery like those published by Drinkwater et al. (2021) that pave the way to developing more advanced surveillance tools that could one day change the world.      

In case you missed it, this publication was also briefly highlighted on this episode of the NPMA BugBytes podcast.

By: Michael Bentley, PhD, BCE


Beng, K. C., K. W. Tomlinson, X. H. Shen, Y. Surget-Groba, A. C. Hughes, R. T. Corlett, And J. W. F. Slik. 2016. The utility of DNA metabarcoding for studying the response of arthropod diversity and composition to land-use change in the tropics. Sci. Rep. 6: 1–13.

Drinkwater, R., Clare, E. L., Chung, A. Y. C., Rossiter S. J., Slade, E. M. 2021. Dung beetles as vertebrate samplers – a test of high throughput analysis of dung beetle iDNA. BioRxiv 2021.02.10.430568.

Robson, H. L. A., T. H. Noble, R. J. Saunders, S. K. A. Robson, D. W. Burrows, And D. R. Jerry. 2016. Fine-tuning for the tropics: application of eDNA technology for invasive fish detection in tropical freshwater ecosystems. Mol. Ecol. Resour. 16: 922– 478 932.

Nguyen, B. N., E. W. Shen, J. Seemann, A. M. S. Correa, J. L. O’donnell, A. H. Altieri, N. Knowlton, K. A. Crandall, S. P. Egan, W. O. Mcmillan, And M. Leray. 2020. Environmental DNA survey captures patterns of fish and invertebrate diversity across a tropical seascape. Sci. Rep. 10: 1–14.

Take a Quiz to see if you Fear Spiders Like Some Entomologists!

Award ceremonies are typically not extremely exciting events. This is not to say that I don’t love them and enjoy fraternizing with my fellow industry folks in jubilant celebration. These events are entirely necessary for industries or organizations to recognize their most distinguished, brightest, or exemplary people. However, the Ig Nobel Prize awards held at Harvard annually falls into an entirely different bucket of award ceremonies that is both fascinatingly weird and delightful, and how I came about to learn that there are entomologists, like myself, that fear spiders. Dr. Richard Vetter won the Entomology prize for his paper “Arachnophobic Entomologists: Why Two Legs Makes All the Difference”.

Forty-one entomologists were selected to complete a “Fear of Spiders Questionnaire (FSQ)”, which is a standardized test used in psychology (Szymanski and O’Donahue 1995); and also rate their fear and disgust of spiders; and answer other questions regarding negative spider experiences and reasons of spider fear. The average score for these entomologists was a 28.2, so they were just somewhat adverse to spiders.

However, it gets interesting when you dive into the entomologists that scored high on the spider fear scale and would be considered arachnophobic. In regards to the statement “Spiders are one of my worst fears”, five entomologists gave the highest “totally agree” score.

A forensic entomologist who routinely handles maggots, gave spiders a maximum disgust score and replied “I would rather pick up a handful of maggots than have to get close enough to a spider to kill it.”

Nineteen of the 41 entomologists stated they had negative incidents with spiders. These happened both in youth and in adulthood. Respondents listed exposure to spiders crawling on them, bites or presumed bites, seeing large orb weavers in webs or running into them, having nightmares about them, and being tormented by family members or peers. Three entomologists specifically mentioned exposure to black widow spiders as one of their negative experiences.

One of the reasons entomologists described spiders negatively was because of their many legs – all spiders have 8 legs. I would laugh, if I were not a spider fearing entomologist, because we entomologists routinely handle 6 legged creatures. It seems those two extra legs, as the author’s title states “makes all the difference”. Also the real, or mostly perceived, notion of spiders running fast, showing up unexpectedly, having dangerous bites or just being ugly were all reported as why they evoke such negative emotions.  

If you are a pest management professional or entomologist that fears spiders – you are not alone! Arachnophobia usually develops in childhood. Most people don’t know the exact moment they became fearful but they have always been afraid of spiders. Entomologists who fear spiders have similar fears as the general public and not surprisingly, developed these fears way before considering entomology a career. So, I’ll continue to slay bed bugs all day but squeal like a child when I run into a spider web in a cold, dark crawl space.

Curious to see how you score on the Fear of Spider Questionnaire? Check this link to take the quiz. * We are bug doctors, not psychologists, so we can’t help you with any of your spider fear. We can only commiserate with you.

Brittany Campbell, PhD, BCE

Vetter, R. S. (2013). Arachnophobic entomologists: when two more legs makes a big difference. American Entomologist59(3), 168-175.

Szymanksi, J. and O’Donohue, W. (1995). Fear of spiders Questionnaire. Journal of Therapy and Experimental Psychiatry, 26(1), 31-34.

Undertakers and Corpse Disposal In The Termite Colony

In North America, termites cause more than $5 million in damage each year. Eastern Subterranean termites are the most widely distributed and most common encountered termite pest in North America. With colonies that can grow to the size of 5 million individuals and assuming a death rate similar to comparable termite species, it is estimated that as many as 70,000 termites could die in colonies each day. Corpse removal, a duty performed by worker termites called “undertakers” is extremely important for colony health. The longer a termite corpse remains, the greater the chances for disease spread. So, undertaker behavior (removal and disposal of dead termites), performed by worker termites,  is extremely important for colony health.

Eastern Subterranean termites have developed two distinct behaviors to deal with dead nestmates: cannibalism and burying the dead. Cannibalism or eating the dead, provides an important service to the colony by recycling nutrients back in the colony. Wood, which is the primary food for Eastern subterranean termites is notoriously lacking in nitrogen. By eating the dead, nitrogen-rich material from the corpses  is recycled back into the colony.  Additionally, gut symbionts, necessary for digesting cellulose may also be recycled. Burying behavior, on the other hand, ensures that the threat of entomopathogens and subsequent disease is eliminated from the colony, which is especially important for eusocial insects living inside the closed system. 

When a termite dies is begins to emit certain chemicals as it decomposes, including airborne volatile compounds such as 3-octanol and 3-octanone are released.  This tells the workers that they are dead and they need to be taken care of.  These chemicals do not persist for long and dissipate over time. Fatty acids are also produced, which are persistent. These chemicals build up in the corpse over time. The relative amounts of these chemicals in a termite corpse can provide information to undertakers to help determine what to do with the dead termite. New corpses were eaten if they were less than 64 hours old (higher levels of 3-octanol, 3-octanone) lower levels of specific fatty acids.

As a part of a series of laboratory experiments Jizhe Shi and his colleagues at the University of Kentucky learned the following information. Based on the levels of these chemicals encountered by undertaker termites (lower levels of 3-octanol and 3-octanone, and higher concentrations of fatty acids) older corpses were dealt with in two ways: either burying or walling off. All “old” worker corpses were buried or covered up with sand particles, feces, or other materials soon after discovery.

Interestingly, soldier termites were buried 50% and walled off about 50% of the time. When walled off, the entire tunnel to the chamber in which the dead soldier termites were present was blocked off.  This behavior seems to be adapted for situations in which the colony is breeched by invading ants/termites and large numbers of dead soldiers remain. Workers instinctively block off that entire area because it’s perceived as unsafe, and the dead termites present there serve as  reminder of danger if the area is opened up in the future.

It is notable that workers produce greater amounts of 3-octanol and 3-octanone upon death and were dealt with more quickly than soldiers. The authors of the study hypothesized that this was because of the greater proportion of workers present in the colony compared to other castes.  Due to sheer the numbers present, workers need to be cleaned up first. 

So, what does this mean for termite control? At first glance, the practical implications for our industry might not seem obvious – because they aren’t. This research does tell us that termites are not using visual cues like we might to determine the age of a corpse.  Remember when the gang from the Goonies found One-Eyed-Willie on his ship while being chased by the Fratellis?  They knew One-Eyed Willie was dead by looking at him, not sniffing him. Termites would have used chemical cues instead to know that he needed to be buried and not eaten.

This is the kind of research that might be categorized in the “cool to know” category, but it could actually impact on-the-ground pest control in the future.  By having a better understanding of how termites deal with their dead, the cues they use, and the behaviors those cues elicit, one could imagine how this knowledge could be used to enhance termite exposure to biological or chemical control products in the future.

This research was recently published in the Annals of the Entomological Society of America based on work performed by Jizhe Shi and his colleagues at the University of Kentucky working in Joe Zhou’s lab. Find out more about this research here: Managing Corpses from Different Castes in the Eastern Subterranean Termite

Jim Fredericks, PhD, BCE