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 charismatic 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. 

 

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