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Friday, January 27, 2012

Unusual Bird Sighting: Common Yellowthroat

Sam Easterson has caught a relatively unusual occurrence on camera. On New Year's day Sam's camera trap discovered a Common Yellowthroat (Geothlypis trichas) skulking behind one of our sheds (I should add that this is the same shed the opossums have a den underneath). It is relatively unusual only because of the season, this is only the third time a Common Yellowthroat has been sighted here in winter!

New Year's day sighting of female Common Yellowthroat

According to Kimball Garrett, our Ornithology Collections Manager, the Common Yellowthroat is a widespread North American wood-warbler, breeding in marshes and wet meadows and scrublands over most of the continent. In Exposition Park, Kimball usually observes yellowthroats in the Rose Garden, where the dense beds of roses provide good places to hide. Of course we hope that as the vegetation in the North Campus becomes established we'll begin to find them here too.

Same bird caught on camera 14 days later

All told Kimball has spotted the Common Yellowthroat 66 times in Exposition Park since he began surveying the area in 1984. Sixty-two of those sightings occurred during the bird's fall migration, between 27 August and 2 December. Kimball has also recorded two additional sightings during the bird's spring migration in April. Prior to this year's winter sighting, Kimball has observed the yellowthroat twice in mid-winter  on 27 January 2010 and 6 January 2011. This is why it was a bit of a surprise when Sam's camera trap recorded the visit of a female Common Yellowthroat earlier this month. According to Kimball, "modern technology is clearly better than an old human field ornithologist in keeping track of more secretive birds!" Regardless of the mode of sighting this record is good news. It suggests that the plantings in the North Campus will provide an important habitat that is lacking in the urban core. We are planting dense low vegetation that is the domain of wrens, Geothlypis warblers, various sparrows and other bird species that are rarely seen in your common urban park that is dominated by trees and lawns.

Thanks Kimball for your detailed bird records and natural history information of the Common Yellowthroat!

Friday, January 20, 2012

Aphid Eating Flower Fly Found in North Campus

There are over 150,000 species of flies in the world! Most visitors who come to the Museum can name only a few of these flies (house fly, horse fly, or mosquito for examples) and many hold the belief that we would be better off without flies in our world. On Wednesday, January 18, we found a fly that I am sure will help you realize that all flies can't be cast as "bad" characters I introduce the humble aphid eating flower fly, Eupeodes volucris.

Female Eupeodes volucris
Photo taken by Jerry Friedman

Why do people like these flies and not others? This isn't an easy question to answer, but I'll have a go... First of all, these flies eat aphids and as any gardener will tell you, aphids are a serious garden pest. Secondly, they belong to a family of flies known as flower flies so called for their proclivity to visit flowers and suck down nectar. Thereby they play a role in pollination. Finally, if you look closely at these small flies you'll see why a lot of geeky people, like myself, think they are quite beautiful. Not only are they brightly colored and highly patterned, when their eyes catch the sunlight just right they have an iridescent sheen! Although I might add that E. volucris isn't as flashy as its close relative, the aptly named stripe-eyed flower fly, Eristalinus taeniops, also a native to the Los Angeles area.

Stripe-eyed flower fly
Photo courtesy of What's That Bug website

How does a fly eat an aphid? It is actually the larval stage of the fly, or maggot that chows down on aphids. Much like immature ladybugs they trawl through a sea of aphids on a plant and chomp any that get in their way!  Though they don't have quite the same look as a ladybug! 

Flower fly maggots eating oleander aphids
Photo courtesy of What's That Bug website

To find out more our local flower flies, swing by the Museum gift shop to get a copy of our latest entomological publication, Flower Flies of Los Angeles County.

Flower Flies of Los Angeles County

Thanks to Brian Brown and Jim Hogue for supplying fly information and identifying the fly specimen.

Thursday, January 5, 2012

Walking Sticks Mysteriously Appear in Museum

Last Friday two Indian walking sticks, Carausius morosus, mysteriously showed up inside the Museum! They didn't escape from the Insect Zoo (we've never kept this species of walking stick before), and we haven't been able to find out exactly how they got here. What we do know is that the insects were discovered after a visitor felt one "fall" on his arm, and then promptly reported it to a staff person.

One of the Indian walking sticks found in the Museum!

Indian walking sticks, a.k.a. laboratory walking sticks, are one of the most common walking sticks around. They are often kept as pets and classroom teaching tools, and their eggs can even be purchased on eBay for fish food! Surprisingly these insects have recently established themselves in our area through inadvertent or purposeful introductions. How does one inadvertently introduce stick insects into the environment?

Indian walking sticks can reproduce parthenogenetically, that is without sexual reproduction. Therefore females can produce eggs regardless of the presence of males. The eggs are very small, about 3mm in length, and look a lot like tiny stones. Female sticks lay their eggs by dropping them directly to the ground, where they accumulate in the leaf litter. When they are in captivity, fecal material, partially chewed leaves, and eggs accumulate very quickly at the bottom of walking stick enclosures. To keep the insects clean and safe it is important for owners to clean this material out on a regular basis. For the untrained stick keeper, it is very easy to inadvertently discard eggs. Often this will be directly into the trash, or maybe even into the backyard compost pile. Paired with purposeful introductions, "I can't keep this pet anymore, I'm sure it will be better outside," is it any wonder that these insects have established themselves in numerous areas around Los Angeles?

Indian walking stick eggs
(photo courtesy of Dr. Arakelian)

According to Dr. Gevorak Arakelian, Senior Biologist in the L.A. County Department of Agricultural Commissioner, Indian walking sticks have recently been downgraded from a B rating to a C rating. This means that they aren't viewed as serious pests that need to be eradicated. However, for gardeners and the nursery industry these insects can still be troublesome. They eat a wide variety of landscape plants including rose, bramble, camelia, hibiscus, geranium, oak, and English ivy (the list goes on). Next time you find mysterious chew marks on your rose bush, take a closer look and see if you can find a walking stick hiding nearby.

For more information check out Dr. Arakelian's Indian walking stick fact sheet.