A Charismatic Cockroach in California

Figure 1: Mix of adult female and male three-lined roaches (Luridiblatta trivittata)

Scampering through leaf litter and grassy landscapes, upon first appearance these flashy little insects might not look like cockroaches, but in fact, they are. They are the smallest cockroaches we have in California, with adults averaging between 5-7mm in length. They are commonly known as the three-lined roach, or if you want to be more scientific, Luridiblatta trivittata; but either way, these charismatic cockroaches are not originally from California, they are native to North Africa and the Eastern Mediterranean.

Figure 2: Female Luridiblatta trivittata carrying an egg case called an ootheca

The three-lined roach first made its debut in California around 2004 in Marin County, but was not positively identified until the Essig Museum’s very own Cheryl Barr, aquatic beetle expert and former Collection Manager, submitted a specimen from her backyard in 2009 to the California Department of Food and Agriculture. Since then, Luridiblatta trivittata has slowly expanded its range to include the Bay Area, San Luis Obispo to the South, to the foothills of El Dorado County in the East, and to Mendocino County to the North.

Though the three-lined roach lives in some of the most densely populated parts of California, these are not the kinds of roaches that want to live in your kitchen. These critters prefer to live outdoors in partially irrigated or dry landscapes and can be found in matted thatch, compost bins, and leaf litter. Occasionally in summer and fall, adults will wander indoors through poorly sealed doors and windows.

We don’t fully understand Luridiblatta trivittata’s biology and ecology, but recent field observations reveal they only have one generation per year. Juveniles hatch around mid-April, and develop through spring and early summer, eventually maturing into adults during July and August. Once mature, females lay egg cases (called oothecae) that will overwinter until next spring. Interestingly, juveniles cannot hatch from their ootheca without precipitation in spring. On the other hand, too much water throughout the overwintering cycle will kill juveniles before they can hatch. It seems our Mediterranean climate, with long dry summers and short wet winters is the Goldilocks of ideal habitats.

Fun three-lined roach facts:

  1. Knowing your Latin roots in biology can be very helpful in understanding scientific names. Luridiblatta for example, can be broken down into ‘luridus’ meaning something has a wan or yellow coloring, and ‘blatta’, which is Lain for a light-shunning insect (incidentally, all cockroaches are in the group Blattodea). The species name trivittata refers to this particular species. ‘tri’ means to have three, and ‘vitta’ means stripe or line. Therefore, we can conclude that the scientific name is referencing a light-colored cockroach with three lines.
    Figure 3: Females with an ootheca at different stages of development
  2. Oothecae of this species start out mint green in color. As an ootheca develops, it turns olive green and then dark brown before they are eventually deposited into the landscape.
    Figure 4:  Left-Female, Right- Male
  3. Males and Females are relatively easy to tell apart. Males have long forewings that extend down the length of the body. Females have short forewings that leave the abdomen completely visible.

References:

  1. California Plant Pest & Disease Report Vol. 25. 2009. CDFA
  2. Proposal for New Common Name Luridiblatta trivittata, Entomological Society of America
  3. Cockroach pest note, 2019
  4. Andrew Sutherland. Luridiblatta trivittata post on Linkedin, 2020

– Photos & text by Casey Hubble, please contact cwhubble@berkeley.edu for photo usage

Oak moths return to Cal campus

Oak moths return to Cal campus

Eggs, caterpillars, pupa, and adult of Phryganidia californica.

The California oakworm or oak moth (Phryganidia californica), returned to the UC Berkeley campus for the second year in a row.

In June 2019 the Essig Museum received a call from a reporter at the Daily Cal asking about moths flying around oak trees on campus. Normally people do not notice the moths, but they certainly notice the onslaught of caterpillars eating the leaves of coast live oaks (Quercus agrifolia), and occasionally other oak species. By August many trees on campus were stripped bare. But by the end of October they recovered. In May-June 2020 we are witnessing the return of the oak moth.

The same tree at Sproul Hall: defoliated (August 15, 2019), recovered (October 3, 2019)

Oak moths typically have two generations per year – one in the spring and one in the fall. As of June 2020 we are seeing the spring caterpillars emerge as adult moths and laying eggs. These eggs will turn into caterpillars that will continue to defoliate trees in August and September. The caterpillars seem to focus on individual trees, rather than attacking all trees equally. This probably has to do with where the females lay their eggs, but the defensive chemistry of the oak trees may play some role.

This chemistry may also play a role in protecting the caterpillars and moths from birds and other predators. Many non-toxic moths and caterpillars hide during the day and feed at night. But oak moths and their caterpillars are very active during the day and do not seem to attract flocks of birds. Their main predators seem to be parasitoid wasps.

Feeding damage by Phryganidia caterpillars.

Once finished feeding on a tree, the caterpillars lower themselves by silk threads that can blow them to another tree to continue feeding, or two the ground where they will wander in search of a place to pupate. In nature these caterpillars would find a crack in the tree bark or side of a rock to anchor their pupal case (which looks more like a butterfly chrysalis). On campus these caterpillars can form masses on the sides of buildings, and sometimes crawl  into utility access tubes.

Masses of caterpillars at Campbell Hall in August 2019.

As if the oak trees are not suffering enough, this year is looking like a big year for tussock moths as well. Females of the western tussock moth are flightless and crawl a short distance from their cocoon to lay large masses of eggs. Caterpillars have distinctive tufts of white or cream hairs that can sometimes irritate skin. 

Tussock moth caterpillar and cocoons on coast live oak. 

 

PCOC at UCB

The Pest Control Operators of California infested the Essig Museum on 19 February 2020. They were in town for the Termite Academy, hosted by our own Dr. Vernard Lewis at the Richmond Field Station. The two-day event included lectures, discussions, and events that covered the history of pest control research at UC Berkeley (including a tour of the Villa Termiti), regulation updates, and a lavish dinner at the Faculty Club. Many were surprised to know that the Essig Museum holds the most comprehensive collection of Cimicidae (bed bug family) thanks to the research of Dr. Robert Usinger. We also reassembled the damaged-wood display that was on exhibit at the San Francisco Internation Airport (SFO) last year.

Special thanks to Chris Reardon & Sarah Conrad (PCOC), Andrew Sutherland (UC ANR), and Vernard Lewis (UCB) for making this happen. Photo credits: PCOC (except Villa Termiti by UC ANR)

Ascend with Bay Area Insects

Ride, walk, or jog along the Greenway in Emeryville and you will be greeted by a swarm of Bay Area “bugs”. Commissioned by the city of Emeryville, Joey Rose created two murals, titled “Ascend”, depicting some of the Bay Area’s most important inhabitants – the insects. Part of Emeryville’s park system, this green space cuts through the heart of Emeryville connecting Oakland to Berkeley. “The Greenway hopes to connect people with nature and serves as an “escape” in a historically industrial city,” says Rose. “My murals reflect this ideal. The intended audience is anyone who may happen to see them. It’s important for people of any age or demographic to feel connected to nature and see the importance of preservation.”

For inspiration, Joey visited the Essig Museum to photograph and sketch his subjects. I asked him why insects for this project. “Insects are an often ignored part of the ecosystem. Unfortunately, there is a stigma against insects. They are usually portrayed as being disgusting or scary. I wanted to show the true beauty of insects. This is a sight-specific mural, so I wanted to highlight local and native Bay Area insects. I hope people will be reminded of my painting when they see these insects around the Bay and vice-versa.”

The murals were unveiled on May 10, 2018 at 5768 Peladeau Street in Emeryville to an enthusiastic crowd. “The two figures in the murals are literally being carried by these insects,” says Rose. “I think that is really the core of what I want people to come away with. It’s not so important that they can identify each and every insect. What’s important is to get people thinking about how essential every creature is to not only our ecosystem, but to us (humans) as fellow members of that ecosystem. Even the little guys are important!”

by Peter Oboyski

Fall is for pumpkin spiders

You have probably noticed a lot of these critters around town lately; they seem to be just about everywhere this time of year. These eye-catching little beasts go by many names, including “Cross Orb-Weaver,” “European Garden Spider,” and “Pumpkin Spider,” among others,1,2 but their proper scientific name is Araneus diadematus. (Note: common names like “Garden Spider” or “Pumpkin Spider” may refer to a number of different spider species, which is understandable given that there are an estimated 47,000 (or more)3 spider species on earth! Since we have not come up with 47,000 unique common names for all of these species, it is best to use scientific names to avoid confusion.)

Araneus diadematus are tan, brownish or orange, with yellow, white and black markings and a distinctive “T” or cross pattern on the back of their spade-shaped abdomen. Adults can range from about 6-20 mm in body length, not including the legs.4 Females are much larger than males and have been known to cannibalize hopeful suitors who approach them to mate.5 You are most likely to find these spiders on their characteristic “orb webs”: those beautifully geometric, Charlotte’s Web-style constructions of spiral-shaped silk supported by spokes radiating from a central hub. This web shape is typical of the spider family Araneidae (“orb weavers”).

Although A. diadematus can be found in the Bay Area throughout the year, their numbers and visibility peak in the fall because this is when they reach maturity. They are not native to this region, they originated in Europe, but their range now extends across the U.S. and into many parts of Canada.1 A. diadematus can occur at remarkably high densities in both natural areas (like woods and parks) and urban environments. Whether they truly qualify as “invasive” (which, by definition, would require having a negative impact on the environment) is debatable, but one thing is for sure: they are enormously successful here.

So what are they doing on those lovely spiral webs? Mostly lying in wait for prey, which consists of insects like flies, beetles and aphids.6 The spiral on the web is made of sticky silk, and when unwitting insects blunder into this structure, they get stuck. The insects struggle, creating vibrations through the web. The spiders, although they have poor eyesight, are incredibly sensitive to vibrations, and by resting in the center of the web – where the “spokes” converge – the spiders can detect exactly where to find the prey based on which silk strands are vibrating.7 The spider then uses a combination of biting and silk-wrapping to immobilize the hapless prey before settling down to eat. Since this whole process damages the web, A. diadematus builds a fresh web each day, eating the old one to recycle the silk.

Some people may find A. diadematus creepy or frightening, and these spiders do look formidable when they are fully grown (not to mention that we usually see a lot of them around Halloween!). However, there is no reason to fear these autumnal creepy crawlies: they are completely harmless. Although they do possess venom – as do almost all spiders – the venom’s function is to paralyze insects, not to hurt large vertebrates like us. And while a bite from one of these guys might be painful and cause a small localized reaction8 (much like a bee sting), the chances of being bitten are so slim that it is a non-issue. These spiders are not the least bit aggressive; they like to keep to their webs and mind their own business, and would only bite as a last resort (i.e. if they were about to be squished). So next time you walk through a huge web that a resident A. diadematus thoughtfully constructed right in front of your door, do not panic – the spider is running for the hills as we speak. If you are lucky, your little 8-legged buddy might stumble into your hands and let you take a closer look!

by Susan Kennedy

See also common Bay Area spiders.

References

  1. “Cross Spider.” Washington NatureMapping Program, naturemappingfoundation.org/natmap/facts/cross_spider_712.html.
  2. Bowline, Mariah. “Pumpkin Spider – Araneus diadematus.” BugGuide, Iowa State University Department of Entomology, 2005, bugguide.net/node/view/33907/bgpage.
  3. “World Spider Catalog (2017).” World Spider Catalog. Natural History Museum Bern, wsc.nmbe.ch, version 18.5, accessed on 12 September 2017. doi: 10.24436/2
  4. Araneus diadematus (Cross Orbweaver).” Spiders.us, 2017, spiders.us/species/araneus-diadematus/.
  5. Elgar, M. A. and D. R. Nash. 1988. Sexual cannibalism in the garden spider. Animal Behaviour 36(5): 1511-1517.
  6. Ludy, C. 2007. Prey selection of orb-web spiders (Araneidae) on field margins. Agriculture, Ecosystems & Environment 119(3): 368-372.
  7. Landolfa, M. A. and F. G. Barth. 1996. Vibrations in the orb web of the spider Nephila clavipes: Cues for discrimination and orientation. Journal of Comparative Physiology A: Sensory Neural and Behavioral Physiology 179(4): 493-508.
  8. McKeown, N., R. S. Vetter, and R. G. Hendrickson. 2014. Verified spider bites in Oregon (USA) with the intent to assess hobo spider venom toxicity. Toxicon 84: 51-55.

 

“Bugged” – California Alumni Magazine, Fall 2017

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The Essig Museum of Entomology was featured in the fall 2017 issue of the California Alumni Magazine. The issue explores the many different uses of the word “bug”, as best explained by UC Berkeley School of Information professor, Geoffrey Nunberg, in Krissy Eliot’s article An Entomological Etymology. The feature article on the Essig Museum, by Pat Joseph, explores the past, present, and future importance of The Bug Collection. The magazine also includes For Love of Roaches: confessions of an entomophile by Kaitlyn Kraybill-Voth, a UC Berkeley graduate who spent over three years working as a collections assistant in the Essig Museum.

As if the words and photos are not enough, video journalist Marika Petrey created four short videos that are available below: Introducing Bugged, How to Mount a Moth, How to Kill the Specimen, and Why Entomology? These videos provide a sneak peak into the daily activities of the Essig Museum. Enjoy!

 

 

Butterfly workshop – May 20/21, 2017

The Jepson Herbarium & Essig Museum
Co-Present: 

Butterflies: Biology, Behavior & Identification

May 20-21, 2017
 

Led by the Essig Museum of Entomology’s Dr. Peter Oboyski, this workshop is open to anyone who is curious about butterflies: perfect for naturalists, gardeners, and enthusiasts alike, in this course we will explore the diversity of butterflies, their life cycles and host plants, behaviors, and identification, with a special focus on California and the Bay Area. We will also discuss how to promote butterflies in your own neighborhood by providing resources for both larvae and adults. This workshop includes a tour of the Essig Museum, a field trip to nearby native butterfly habitats, and a visit from some guest speakers!

Visit the Jepson Workshops website for registration information

Enrollment is still open for this course! For more information or to register, contact Allyson Ayalon, Public Programs Coordinator at the Jepson Herbarium. Phone: 510-643-7008. Email: alayalon@berkeley.edu.