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Scientific Protocol Activity: Arthropods

Arthropod Activities

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?

Arthropods 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.

 

Study Arthropods

Why study arthropods?

  • They are important components of any food web.
  • There are many different kinds and in a single collection you can find arthropods which are decomposers, herbivores, predators, and parasites.
  • Because they have short life cycles, they respond quickly to habitat disturbance and changes in soil and vegetation.
  • They are fairly easy to collect.

What arthropods are in your schoolyard?

Using the protocol, you will record the arthropods collected in your schoolyard. From your observations you can investigate how the population compares to those found in other landscape types where CAP LTER scientists are collecting data. You can also investigate what characteristics of the schoolyard are attracting the kinds of arthropods you are finding.

What materials will you need?

  • Bulb planter/garden trowel
  • Metric measuring tape
  • Metric ruler
  • Tweezers
  • Magnifying glass
  • 16-ounce Solo cups and lids
  • Pencils
  • Data sheets
  • Ziploc bags
  • Cooler with blue ice (if you have a freezer in which to store samples, you’ll only use the cooler when you’re outside. If you don’t have a freezer or you don’t want to put your samples in it, then be sure to check the ice periodically).

 

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 LINE.
  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.

Teacher’s Guide: Arthropod Protocol & CAP LTER from Sustainability @ ASU on Vimeo.

 

Arthropods Identification Key

Use the key below to identify your arthropods

Identification Key Used to Identify Orders of Common Arthropods

(adults > 2-5mm in total body length)

  • 1a 6 legs, three body sections Go to 3
  • 1b Not exactly as above Go to 2
  • 2a 8 legs, two body segments, no tail Araneae
  • 2b 10 legs, stinging tail, pinchers on front appendages
  • 3a Wings obvious and/or hard (or leathery) covering. (ladybug) Go to 4
  • 3b Wings absent Go to 11
  • 4a Two wings (or two wings with tiny, vestigal hindwings), no horny or leathery sheath Diptera
  • 4b Four wings (or two wings covered by a horny or leathery sheath) Go to 5
  • 5a Hind-wings partly or entirely covered by horny or leathery sheath (grasshopper) Go to 6
  • 5b Both pairs of wings are entirely membranous (wasp) Go to 10
  • 6a Tube-like mouthparts (for sucking not chewing) Hemiptera (true bugs)
  • 6b Biting/chewing mouthparts Go to 7
  • 7a Body flattened; antennae long and uniformly thin Blattodea
  • 7b Body rounded or square-like rather than flattened Go to 8
  • 8a Hind legs (esp. femur) enlarged (drumstick-like) for jumping Orthoptera
  • 8b Hind femurs not enlarged Go to 9
  • 9a Leathery sheath is short, vest-like and cerci at end of abdomen Dermaptera
  • 9b Leathery sheath capable of completely covering hind wings and no cerci Coleoptera (beetles)
  • 10a Tube-like mouthparts (sucking, not chewing) Homoptera
  • 10b Biting/chewing mouthparts Hymenoptera; Go to 11
  • 11a Elbowed antennae and distinct dorsal bump on slender segment connecting thorax and abdomen Formicidae
  • 11b Antennae not elbowed or no dorsal bump other Hymenoptera

Download printable images of the arthropods identified above.

 

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.

Share and compare your data

Do you want to Enter your Ecology Explorer data? Do you want to view data from other Ecology Explorers Research?

Go to the Ecology Explorers Data Center.

To get directions for using the Ecology Explorers Data Center, click on one of the links below: