What are arthropods?

Are arthropods crawling around your schoolyard?

Arthropods are insects and arachnids, like beetles, flies, ants, spiders, scorpions and ticks.  They are important components of our desert and urban food webs.

What do arthropods tell us about our urban ecosystem?

By comparing arthropod populations among different land use types, we may see how different human activities (farming, industry, building residential communities, watering lawns) affect biological diversity.

How are CAP LTER scientists studying arthropods?

First, scientists ask questions such as:

• How has urbanization affected the number and diversity of arthropod species?
• Are there areas within urban Phoenix that attract more arthropods?

Arthropod habitats

Next, to answer these and other questions, CAP LTER scientists are investigating ground arthropod populations (number and diversity) in several different habitats:

• desert remnant (inside the city)
• desert outside city boundaries
• industrial
• xeric (dry) residential yards
• mesic (heavily irrigated) residential yards
• xeric/mesic combination residential yards
• agricultural fields

Your research adds another habitat type: schoolyards (and/or a wider variety of backyards). Because not all schoolyards are the same, your schoolyard map will be REALLY important when you begin to analyze your data. The vegetation survey also will be important.

Arthropods protocols

1. Use pitfall traps to collect arthropods once a month. The pit traps consist of two 16-ounce Solo cups, one inside the other, buried in the ground so that the top of the cup is ever so slightly below the surface of the soil. (If the top of the cup is above the ground, the bugs will walk around your trap instead of into it.)
2. Use a bulb planter/garden trowel to dig 10 holes in a line, 5 meters apart. If the area in your schoolyard is not long enough for this kind of arrangement, use a grid pattern, but be sure to keep 5 meters between the traps and be sure to indicate the arrangement on your data sheet. Don’t worry if the trap line goes from lawn to shrubs or near trees. Assign a number to each trap. Lets say that you’re collecting 10 samples from the northeast area and 10 others from the west end of the schoolyard at Jone’s Middle School. You could name the first 10 traps Jone’s NE1 – Jone’s NE10 and the second 10 Jone’s W1 – Jone’s W10.
3. Complete a habitat description for each of your trap lines. Record your findings on the site description data sheet. You will need to do this before entering data into the CAP LTER database.You only need to do this once per trap tine.
4. Place the pit traps (Solo cups) in the ground. Remember to use two cups, one inside the other.
5. Leave the traps alone for 72 hours. Why so long? Imagine how long it takes a bug to crawl 5 meters. If you want to get a good idea of arthropod diversity, you need to give the critters time to fall in.
6. After 72 hours, empty the traps into resealable plastic bags. Use a different bag for each trap (all arthropods collected in one trap are called a “sample”) and include a label indicating the collected sample’ s corresponding trap site number.
7. To empty the pit trap, take the inside cup out of the second cup, leaving the second cup in the ground (to preserve the hole you dug). Empty the contents of this cup into the Ziploc bag then replace it in the ground cup. Cover it with a plastic lid or fill it with rocks, until you start the next collection cycle.
8. Once the sample is bagged and sealed, place it in a freezer or ice chest. This will kill any organisms that may have survived the fall into the cup. Leave the samples in the freezer to preserve the arthropods until you have finished identifying them. (As you’re identifying the samples, you may decide to pin and display a collection of some of the larger arthropods.)
9. Take the collected arthropods to your indoor workspace for identification.
10. Download the data sheet and identification key and use them to record your observations.

Share arthropods data

Record your data using the sheet outlines below

Data Sheet: Need a data sheet to record your data? Choose a link below to get a printable data sheet.

• Site and habitat description
• Arthropods Data Sheet

• Teacher directions
• Student directions