Citizen Science Project: Collecting Spiders for the Natural History Museum of Los Angeles County

In March, students in the California Naturalist Program at the Dominguez Rancho Adobe Museum began collecting spiders as part of a citizen science project for the Natural History Museum of Los Angeles County. Led by Jan Kempf, students learned about the museum's ongoing Spider Survey and also received an introduction to spider collecting techniques.

Jan Kempf examines a False Widow Spider (Steatoda grossa)

The Spider Survey is the first comprehensive survey of spiders in the Los Angeles area. According to the Natural History Museum, most scientific collections only include spiders found in natural areas. This study is particularly important because its geographical range is a highly urban area. Located within that area are the major ports of Los Angeles and Long Beach. It is through these two ports that new species of wildlife, including spiders, often make their entry into the United States.

False Widow Spider (Steatoda grossa)

The survey began in 2002. To date, approximately 500 people have participated, and more than 6,280 spiders have been submitted to the museum. Originally, collection data was restricted to Los Angeles County. The popularity of the program eventually led the Natural History Museum to expand its survey area to five southern California counties. So far, the collection represents 33 families, 104 genera, and 75 species. Among them are several new records for the Los Angeles area including:

• Two species of jumping spider -- Plexippus paykulli and Mexigonus minutus

• Three species of orb weavers -- Larinioides sclopetaria, Metazgia zilliodes, and Metazgia wittfeldae

• Two species of cobweb weavers -- Latrodectus geometricus (the brown widow) and Steatoda nobilis

• Two species of Linyphiidae

 

Collecting Spiders

We often think of spiders in relation to the webs they spin. When collecting spiders, though, it is wise to think "outside of the web" and look all around. In addition to webs, consider where spiders may be hiding among plants, underneath bark and rocks, in leaf litter, and on man-made structures.

Hand Collection

This method is excellent for collecting the most visible spiders. Simply trap them, just as you might when you see one walking through your house. Instead of taking it outside, however, or flushing it down the toilet, send it to the museum!

Beating Method

Position a sheet underneath a branch or large leaf, then lightly hit the branch with a stick. You may be surprised to see what falls onto the sheet.

Sweeping Method

Use a butterfly net to sweep through grasses and low-lying plants. Be careful not to use the net around cactus or thorny plants as they will snag the net.

Looking Through Leaf Litter

Select an area that is moist, but not wet. Gather a pile of leaf litter and put it onto a white sheet. Use your hands to move the debris around and look for the movement of spiders.

An alternate method is to scoop leaf litter into a mesh bag such as produce might come in. Shake the bag over the sheet and see what falls out. Choose a bag with large, rather than small openings.

Pit Fall Trap

Pit fall traps are good for catching spiders as they hunt. To make a trap, take a small plastic tub and bury it so that the top is flush with the ground. Pour an inch of soapy water into the tub. One member of our class suggested that a lid can be suspended approximately one inch above the tub so that larger creatures, such as lizards, would not fall in. Be sure to check your trap every day.

Whichever method of collection you select, and you may want to try several, make sure to have containers ready. Our class used clear plastic vials, which can be purchased from biological supply stores such as local Rancho Dominguez company, BioQuip, but any small jar or tub will work.

Precautions

Whenever working with wildlife, whether big or small, it is important to take sensible precautions. Although spiders are predators by nature, we are not their prey, and the majority of spiders do not pose a threat to people. However, in the Los Angeles area we do have two types of spiders which can inflict a harmful bite. They are the black widow and the brown widow. Most people are probably familiar with black widow spiders. They have a shiny, black, rounded body and a red hourglass on the underside of the abdomen. Brown widows are thought to have come from South Africa and were established in southern California in 2000. They have a similar shape to that of the black widow, but the coloration is different. The brown widow's body is primarily brown, with geometric patterning on the abdomen. Additionally, the hourglass shape is more of an orange color. Brown widows also have distinctive egg sacs. When coming across an ivory colored, spiky egg sac, be aware that a brown widow is probably tucked into a nearby crevice.

Black Widow (Latrodectus hesperus)

Brown Widow (Latrodectus geometricus)

Brown Widow Egg Sacs

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

What To Do With the Spiders You Collect

In order for museum staff to make an identification at the species level, dissection is required. Perhaps it doesn't need to be said, but be aware that the spiders will have to be killed in order for scientists to study them. The usual methods of killing spiders employed by most of us (squishing, spraying, and flushing) won't yield a specimen appropriate for study. It is important to treat the spider in a way that will keep its body intact. One method of doing this is to add a cotton ball soaked with rubbing alcohol to the container. A second method is to put the spider in the freezer for 24 hours. Once you have done this, it is time to send your specimen(s) to the museum.

According to Jan, spiders arrive at the museum in all kinds of packaging. About the only way to fail is to enclose your spider in something soft, like a plastic bag, which may result in the spider arriving in pieces. Jan recommends putting the spider into something like an ordinary pill bottle and using a padded envelope for mailing. Make sure to include a data sheet from the Natural History Museum's website with your spider so that the museum will have accurate information on where the specimen(s) were collected. Send specimen(s) to:

Spider Survey
Natural History Museum of Los Angeles County
900 Exposition Boulevard
Los Angeles CA 90007

And that's it. Now go out and discover what's living in your own yard!

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Fun Facts about Spiders:

• Based on the submissions of the most enthusiastic survey participants, the average Los Angeles yard contains 150 spiders, representing 13 families and 21 species. 

• Worldwide there are 38,998 species of spider, distributed among 3,607 genera and 101 families.

• The most common types of native spider in the Los Angeles area are the black widow (Latrodectus hesperus), ground spider (Herpyllus propinquus), funnel weaver (Hololena curta), and orb weavers.

• The most common types of non-native spider in the Los Angeles area are the house spider (Parasteatoda tepidariorum), false widow (Steatoda grossa), cellar spider (Pholcus phalangioides), ground spider (Scotophaeus blackwalli), yellow sac spider (Cheiracanthium mildei), and Oecobius navus.

• Some spider eyes fluoresce at night.

• Reproductive features are only visible after the spider's final molt. Before then, it is impossible to determine gender.

• The only family of spiders that do not contain poison glands is the family Uloboridae.

• Female spiders are larger than male spiders of the same species. An exception is that wandering spiders are similar in size.

References:

Kempf, Jan, "Spider Survey" (lecture, California Naturalist Program, Rancho Dominguez, CA, March 21, 2015). 

"Spider Survey" Natural History Museum of Los Angeles County, accessed April 17, 2015, http://www.nhm.org/site/activities-programs/citizen-science/spider-survey

Vetter, Richard S. "Brown Widow Spider," Center for Invasive Species Research, University of California Riverside, http://www.nhm.org/site/activities-programs/citizen-science/spider-survey