#Title:

option 1: Let’s go bugging: Collecting insects in tree canopies

option 2: What lives in the tree tops: it’s not just for the birds

#Targeted Level: 9th/10th grade

#Difficulty: Advanced 1

#Time Required: 1 Day

#Notes on Time Required: You will need time to locate three different species of tree, collect insects from the trees and bring them home for identification using a key. You will need time to cool down the insects for handling. It will also take time to learn to use a key, but once you get the hang of it, things will move faster.

#Prerequisites: Believe it or not, collecting and handling insects is a skill that you get better at over time. Insect identification at the species level can be difficult, reserved for experts in their fields. In some ways, insect anatomy can be more complex than our own. Identifying insect orders, however, is a much less difficult place to start, since you will be looking at wings and legs. This activity is a good place for the novice insect collector to start!

#Material Availability: (2) Requires specialty items but access to a laboratory is not required

#Material Availability Notes:

#Cost: Low

#Adult Supervision Required: No

#Safety: Be careful with biting, stinging or spraying insects! Follow the procedure for handling insects.

#Abstract:

Insects are classified like all other living organisms. All insects are in kingdom Animalia, phylum Arthropoda and class Insecta. They are further categorized by order according to features on parts of their anatomy, such as mouthparts, wings and legs. Insects occupy a variety of habitats, such as dead wood, soil, aquatic environments, bathrooms and basements. You are going to collect and examine insects captured from trees, making observations about any differences or similarities in the type and number of insects found in three different species of tree.

#Objective: To introduce the student to insect collection and classification.

#Hypothesis: There will be differences in the kind and quantity of insects that are found on three different species of tree.

#Credits: Jessica Watson

#Background:

Insects are feared and abhorred because they’re small, fast, creepy and sometimes destructive and dangerous. They can do damage to our gardens and houseplants (caterpillars, stink bugs), as well as our homes (termites, ants). They build nests on our houses (wasps) and climb the counters in our kitchens (ants). Sometimes they live in our mattresses (bedbugs) and bathrooms (moth flies, silverfish) and basements (earwigs).

In fact, insects are kind of infamous; bug eating contests are held on TV shows. Roach motels are named after them. Some of us have suffered insect stings or bites from ants and wasps. Maybe we have even accidentally eaten them; many types of beetle larvae can be found in stored grains and spices if not properly sealed. Actually, many of the assumptions about insects are wrong. For instance, insects can be quite graceful and even beneficial to us. In some cultures they are eaten for their high protein content. Insects spin the silk we use in clothing. If it weren’t for insects, we wouldn’t have honey and many foods would be missing from the produce section of the grocery store.

Whether you consider them friend or foe, insects are an important part of our environment. Like all living organisms, insects are classified according to the Linnaean system. Insects are classified in kingdom Animalia, phylum Arthropoda and class Insecta. There are approximately 30 different orders of insects.

Insects are sometimes called hexapods because they have 6 legs as adults. There are exceptions to this rule; however, so many people prefer not to use the term hexapod. This means each species is assigned a binomial Latin name, which consists of its genus and species. We humans are Homo sapiens, while your dog is Canis lupus familiaris (yes, all dogs are one species). In the insect world, Apis mellifera is a honey bee.

In this experiment we are going to classify the insects according to order only. We will take advantage of the fact that insects are cold-blooded. The technical term for cold-bloodedness is poikilothermy, which means that insects vary their temperature according to their environment. In contrast, humans are homeotherms because we are able to maintain a constant temperature (about 98.3˚F in fact!) using our metabolism. Of course, we rely on warm clothing in cold weather and many other animals, like insects and birds, either migrate or hibernate when it’s too hot or too cold. In fact, insects have some control over their temperature through behavior. For example, butterflies shiver and bask in the sun to warm up.

Dichotomous keys are charts used to identify organisms based on characteristics you can see with your eyes, even if you need help from a magnifying lens to see them. “Di” means “two” and for each step in the key, there are two choices to choose between which describe a particular

trait. To use a dichotomous key start at step one. At each step in the key, you will have to choose between two different characteristics, choice a or b. Your choice a or b will either give you the name of the insect order, or tell you to proceed to another step in the key. Continue moving from step to step as the key instructs until you have identified the insect order.

#Terms and Concepts:

Entomology Biological classification Order Species Dichotomous key Homeothermy Poikilothermy #Questions:

Can you think of one advantage to being a cold-blooded animal (poikilothermic)?

What types of insects do you think live in trees and why? Provide examples.

#Bibliography:

Recommended web browsing:

Guide to insect orders from Encyclopedia of Life- http://eol.org/collections/38915

Overview of insect orders on Bugguide- http://bugguide.net/node/view/222292

#Materials and Equipment:

White bed sheet Stick Access to 3 different species of tree with branches that can be reached Collecting vials available from a biological supply company (plastic or glass; plastic is lighter weight and less expensive); at least 15 (5 per tree) Bag to carry vials Tweezers Cardboard Sewing pins Access to a refrigerator or large cooler with ice Magnifying lens or dissection microscope (at least 10X)

Plastic and glass hand lenses as well as Sherlock Holmes magnifiers are available in a range of prices from biological supply companies ($2-$40)

#Experimental Procedure:

1) Locate three different species of tree, preferably flowering trees. Most non-flowering trees are evergreens, so choose non-evergreen trees. Although insects do frequent some non-flowering trees, they are more likely to be abundant on flowering trees.

If you don’t know what species the tree is, that’s okay. Just make certain that the three trees are different. You can do this by comparing leaf shape, number and arrangement of leaves on each branch. If the tree is flowering, compare flower color, number of petals per flower and arrangement of flowers. If the tree is fruiting, compare fruit. Botanists also use features of the bark to identify tree species, but that can be tricky.

Hint: You will have better luck finding insects if you look for feeding damage on the tree’s leaves. Feeding damage includes skeletonization or holes in the leaves, which indicate the tree is tasty to insects. Trees with no feeding damage may not be good host plants.

2) Start with one of your three chosen trees. Choose three branches to beat from this tree. Lay the white sheet directly underneath the first branch and tap with a stick. Make sure you hit the branch itself and not the leaves. If you hit too hard you may break the branch, and if you hit too lightly the insects won’t fall off the branch. You can also work your way down the branch towards the tip.

3) As you sample each branch, record the number of insects on each sheet, using table 1 provided. If there are no insects, mark 0 on the table. If there are insects, count the total number of insects on the sheet. If there are too many insects to count, estimate the total number by counting a section and multiplying by the total number of sections. Record the number in the data table.

The beating sheet is positioned directly under the branch you are going to sample.

3) If there are insects on the sheet after beating, capture them using your collecting vials. If there are too many insects to collect, choose 5 insects at random from the sheet. Don’t collect too many insects. It will take some time to learn to use the key, so taking only a few insects from each tree is sufficient.

Some insects, like treehoppers, may move so fast you won’t be able to collect them. Some insects, like caterpillars, may be easily picked up and transferred to the vial. To collect other insects, you can cover the insect on the sheet with the open end of your collecting vial, reach your hand under the sheet while holding the vial in place, and gently push the insect inside the vial. Finally, slide the cap under the vial, keeping it in position so the insect doesn’t escape.

In the above example, only one weevil was found on the sheet after beating.

4) Repeat steps 2 and 3 with all 3 branches for each of the three trees.

5) Bring the insects back to your station to examine. This may be your home or a lab. Place the insects in a refrigerator for several hours to slow them down. This won’t kill them and you will be able to release them after examining if you handle them carefully.

6) After you have cooled down the insects, take them out one by one, so that they remain cool for handling. First, try to get used to using your magnifying lens for observing parts of the insect. Set the insect on the cardboard. With one hand, hold the magnifying lens and with your free hand move the insect with tweezers as needed. You may want to place pins around (not on or in!!) the insect to hold it in place.

7) Once you have figured out how to magnify the insect, turn to the dichotomous keys provided by the American Museum of Natural History: http://www.amnh.org/learn/biodiversity_counts/ident_help/Text_Keys/text_keys_index.htm  

To  identify  insects,  you  will  use  either  Key  A  or  B,  for  arthropods  with  6  legs.      Please  note  that  larval  forms  of  insects,  like  flies,  beetles  and  caterpillars,  may  have  more  or  less  than  6  legs.      

Key  A  is  for  insects  with  well-­‐developed  wings,  while  Key  B  is  for  insects  with  tiny  or  missing  wings.    Some  orders  appear  on  both  keys.    Below  is  a  list  of  orders  from  each  key.    The  orders  you  will  most  likely  find  on  trees  are  highlighted  in  bold  text,  while  the  orders  you  probably  won’t  find  have  N/A  next  to  them.  

Quantity of Insects Tree 1 Tree 2 Tree 3 Branch 1 Branch 2 Branch 3

Total Table 1. Total quantity of insects.

Insect Orders Tree 1 Tree 2 Tree 3 Key A

Diptera (larval) Ephemoptera N/A Lepidoptera (larval) Trichoptera N/A Homoptera Neuroptera N/A Psocoptera Odonota N/A Isoptera Mecoptera N/A Hymenoptera N/A Plecoptera N/A Ephemeroptera N/A Heteroptera Coleoptera Blattaria Mantodea Orthoptera

Key B Phasmida Collembola N/A

Thysanura N/A Homoptera Isoptera Psocoptera Thysanoptera Hymenoptera (Ants & wingless wasps)

Siphonaptera N/A Dermaptera Coleoptera Total # Insect Orders Collected

Table 2. Insect orders collected by tree

#Discussion:

Using your completed data tables, make some conclusions about the trees you collected insects from. Were there any differences among the three trees in number and type of insects collected. Why or why not? Use observations about the tree or the insects to inform your conclusions. #Make it Your Own:

Choose a tree that you have previously collected insects on. Collect insects from this tree once a week or once a month by following the procedure here and accurately recording data about quantity and number of insect orders for each collecting trip. After you have collected from the same tree on 5 different weeks or months, use your data tables to compare your collections. On what days did you find the most number of insects? On what dates did you find the most insect orders? Why do you think you got the results you did?

#Answers to Questions:

1) One advantage to being cold-blooded is that since you don’t use your metabolism to stay warm, you don’t need to consume as much energy. Some insects spend an entire stage of their life, such as larval or adult, without eating. Humans, on the other hand, have to continually eat throughout life.

2) The types of insects that live in trees are not very good fliers, so they tend to walk rather than fly. They probably like to munch on leaves, pollen, petals or nuts, suck sap or eat other insects that munch on leaves. Some of them may have adaptations unique to living on plants, such as twig or bark mimicry.