Hanna Kahl working in the field.

 “They feed mostly at night and hide during the day,” according to the UC Statewide Integrated Pest Management Program. They hide in the bark crevices, mulch, and “protected compact plant parts such as dried, curled leaves, and under trunk wraps.” 

“Earwigs feed on dead and living insects and insect eggs and on succulent plant parts, UC IPM says. "Earwig nymphs and adults will climb trees and feed on flower buds, leaves, and fruit of trees during the spring flush months (March through May). Nymphs tend to feed on plant material more than adults...Earwigs can be very problematic on young trees with trunk wraps or cardboard guards, in which they reside. They climb the trees and feed on the new leaves. Large numbers of earwigs can defoliate trees.”

Enter ecological pest management specialist Hanna Kahl, who recently received her doctorate in entomology from UC Davis, studying with UC Davis distinguished professor Jay Rosenheim. She'll present her exit seminar on “Herbivory of Citrus Fruit by European Earwigs in California” at 4:10 p.m, Wednesday, Sept. 29 in Room 122 of Briggs Hall. This in-person will be the first of the UC Davis Department of Entomology and Nematology's fall seminars. Many of the others will be virtual. 

“Growers and pest control advisors in California suspect that European earwigs (Forficula auricularia) damage young citrus fruit,” Kahl writes in her abstract. “However, very little is known about herbivory by earwigs on citrus fruit. Our work details characteristics of herbivory by earwigs on citrus fruit and the use of sticky and pesticide barriers to manage earwigs and other citrus pests.” 

Kahl, awarded her doctorate in August, focused her research on understanding the role of European earwigs in California citrus; developing a whole systems approach to manage earwigs and other citrus pests; and feeding preferences of fort-tailed bush katydids and citrus thrips on California citrus. 

Kahl is now an ecological pest management specialist at Community Alliance with Family Farmers, Davis. She leads projects and extension efforts on sustainable pest management tactics. 

She received an ongoing grant in 2019 from the Citrus Research Board on “Characterizing Earwig Damage to Citrus Fruits, and Damage Prevention using Trunk Barrier Treatment.” She also received a National Science Foundation Graduate Research Fellowship, awarded in 2017, and a 2018-19 Keller Pathways Fellowship (for entrepreneurship) from the University of California.

Active in both the Entomological Society of America and the Ecological Society of America, she won first place in the Student 15-Minute Paper Competition at the 2016 meeting of the International Congress of Entomology; and second place in the Student 10-Minute Paper Competition at the 2019 meeting of the Entomological Society of America (ESA). She served on the Eastern Branch team that won second place in the ESA's 2016 Linnaean Games, now called the Entomology Games. She co-organized  a seminar, “Agroecology with Communities: Cross-Disciplinary Collaborations Between Ecology, Agriculture and Social Science,” for the Ecological Society of America at its 2019 meeting. 

Kahl received her bachelor's degree in biology from Whitman College, Walla Walla; her master's degree in entomology from the University of Maryland, College Park. At Whitman College, she researched the effects of reservoirs as habitat barriers on song sharing of the birds, dickcissels. At the University of Maryland,  she focused her research topics on effects of red clover as a living mulch cover crop on arthropod herbivores, natural enemies, pollination and yield in cucumber; (2) consumptive and non-consumptive effects of wolf spiders on cucumber beetles and (3) effects of red clover living mulch on greenhouse gas emissions.  She studied abroad in a six-month School for International Training program in Jaipur, Rajasthan, India in 2010. Her research topic: Village dairy production in Haryana and Orissa.

Her current activities include being the chapter leader for Women in Data (WID), Sacramento. 

Kahl's exit seminar will be recorded for later viewing, according to seminar coordinator Shahid Siddique (ssiddique@ucdavis.edu), a nematologist and assistant professor, UC Davis Department of Entomology and Nematology. The seminars take place every Wednesday at 4:10 p.m. Many are virtual.

One point about insect wedding photography is that you don't need an invitation to attend. You just have to keep your distance and not disturb the bridal couple.  No sudden movements. No stressful impatience. And no camera flash, please.

It helps, though, if you grow the host plant so a bride and a groom will show up. In this case, we grew passionflower vine (Passiflora), the host plant of the Gulf Fritillaries (Agraulis vanillae).

One morning we saw a butterfly eclose from her chrysalis. Wedding Day! Within minutes, a male suitor arrived.

They became a couple.

Then unexpected guests arrived...a hungry caterpillar munching on the leaves and a second prospective suitor (PS) (rejected) and a third PS (rejected) and a fourth PS (rejected).

PS, leave them alone!

When the "ceremony" ended, the couple simply left. One sipped nectar from the nearby Mexican sunflower, Tithonia rotundifola. The other flew over the fence.

Soon we'll have more eggs, more caterpillars, more chrysalids, and more adults. 

Life is like that when you're growing Passiflora and hoping for a Wedding Day.

Where are the monarch butterflies? They're MIA on the four species of milkweed in our Vacaville pollinator garden  

But milkweed attracts other insects, including honey bees, carpenter bees, bumble bees, assassin bugs, syrphid flies, leafcutter bees, Anthophora (genus) bees, wasps, praying mantids, and butterflies, including Gulf Fritillaries, Agraulis vanillae, and gray hairstreaks, Strymon melinus. And yes, arthropods such as crab spiders and orbweavers visit, too.

On Sept. 19, we witnessed a gray hairstreak laying eggs on the buds of a tropical milkweed, Asclepias curassavica, which we planted in a container with another milkweed, butterflyweed, A. tuberosa. (Yes, we give the monarchs a choice; we also offer them showy milkweed, A. speciosa, and narrowleaf milkweed, A. fascicularis, and we cut back the A. curassavica before the fall migration, as noted entomologists recommend.)

Butterfly guru Art Shapiro, UC Davis distinguished professor of evolution and ecology, says this about the gray hairstreak on his website, Art Shapiro's Butterfly Site:

"This is one of the most polyphagous butterflies known, recorded on host plants in many families. Its most frequent hosts in our area are mallows, including the weedy species of Malva; legumes, including Spanish Lotus (Lotus purshianus), Bird's-Foot Trefoil (Lotus corniculatus), White Clover (Trifolium repens) in lawns, Alfalfa (Medicago sativa) and many others;and Turkey Mullein (Eremocarpus or Croton setigerus, Euphorbiaceae)." 

So, we mentioned the gray hairstreak laying eggs on the buds of the milkweed. "Is this a host plant, too?"  

"Apparently on the flower buds! Never before recorded--in fact, I have no records on Asclepiadaceae/Apocynaceae at all," Shapiro said. "They lay on Callistemon (bottlebrush) too..."

Meanwhile, update: no monarchs, no eggs. We're still waiting.

But "yes" on the gray hairstreak, Strymon melinus, and "yes" on her eggs. 

Find the praying mantis.

That's not too difficult, considering this Stagmomantis limbata is gravid (pregnant) and about ready to deposit her ootheca (egg case or "ooth") on a nearby twig or branch.

Sandwiched herself between African blue basil and Salvia “hot lips"--where the bees are--she found easy pickings.

According to Bugguide.net:  "Females most often fairly plain green (often yellowish abdomen), but sometimes gray, or light brown, with dark spot in middle of tegmina. Tegmina do not completely cover wide abdomen. Hind wings checkered or striped yellow. Blue upper lip more pronounced in females, brighter in green forms and darker in brown forms."  

A day after this image was taken, the mantis vanished. 

Ooh, there's an ooth out there somewhere.