How to Raise a Caterpillar: Introduction to the Zoo

Our work on this project can be subdivided into fieldwork and lab work. Explained briefly, field work involves whacking trees with sticks and hoping caterpillars come flying off.

(Kristy demonstrating proper tree-whacking technique)

After we collect caterpillars from trees and organize them into labeled plastic cups, they get taken back to the lab for processing. During these steps, each caterpillar is assigned a number, officially identified by species, and photographed. After all that is complete and there is a record for each caterpillar, they get sent to the zoo.

(part of the lab setup at the Southwestern Research Station)

(closeup of the zoo--caterpillars are arranged according to their host plants)

The zoo is where the caterpillars live until they die (whether due to parasitoids or not) or pupate. While they are in the zoo, they must be checked on regularly. Once a day or so, each caterpillar needs to be "zoo"ed. The process is as follows:

Step One

• Pick out a caterpillar that needs to be taken care of. We typically would each take a stack of one host plant and work our way through it before moving on to the next.

(one section of the zoo in Arivaca)

Step Two

• Before opening the cup, check to see if you can identify the caterpillar and/or any parasitoids that might be present. This is important so you don't lose any specimens. If you see that the caterpillar appears to have died or pupated, their cup gets moved to a different location.

(Can you see the caterpillar in this cup of mesquite? It's yellow and fuzzy.)

Step Three

• Find your host plant. This is the caterpillar's food and is typically the plant on which the specimen was found. We keep a few big coolers of host plants in labeled zipper bags.

(Ruben looking through bags of different host species)

(Found the mesquite!)

(If we're out of something, we add it to a grocery list so it can be collected at the next opportunity.)

Step Four

• Dump (or gently pull out) the contents of the cup onto a paper plate. The white plate is a nice background surface for keeping things contained and spotting tricky caterpillars. It also gives you a chance to observe the caterpillar for any bruising or other signs of parasitoid activity.

(caterpillar, host plant, and frass)

Step Five

• Use a brush to clean out the inside of the cup. As the caterpillars eat and grow, they can produce a lot of frass (excrement), so we want to get rid of all that before we put them back.

(This fuzzy guy would not stay on the plate.)

Step Six

• Put the host plant into the newly-cleaned cup. It's a good idea to put the plant in first so you don't inadvertently crush the caterpillar with it.

(cup full of talinum)

Step Seven

• Put the caterpillar back in the cup. This can vary in difficulty depending on the caterpillar. Some of them will crawl right in while others need more cajoling.

(Success!)

Step Eight

• Close the lid carefully and securely and put the caterpillar back in the zoo. Then move on to the next cup. We collected every day, so there were almost always caterpillars who needed care.

(sunset at Arivaca)