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Bug of the Week: Reactions to Genista Caterpillars

April 1, 2020 / Roberta / 0 Comments

A few weeks ago a friend and I visited the Desert Botanical Garden. As we passed by a Texas Mountain laurel plant, I noticed a caterpillar.

Okay, maybe I knew where to look.

A couple of other people came by, and saw that my friend and I were peering into the bush. I was struck by how different their reactions were.

A young boy spotted one and exclaimed, “Look, a caterpillar!” Soon he had found one after another, excited at each one, pointing them out to us.

A man –probably his father– came up and said, “A pest.”

They walked on.

Obviously, each of us has a unique perspective. For example, I knew the insects were called genista caterpillars, Uresiphita reversalis, and when they finished development they would turn into a moth. I’ve seen genista caterpillars every year in the spring on Texas mountain laurel plants for over a decade. The caterpillars feed while the plant is flowering, then disappear–pupate and overwinter as a pupa — until the following year (see a photograph of an adult and a pupa). Generally the plant recovers after the caterpillars pupate, so no need to do anything about them.

Also, Texas mountain laurel leaves and bright red seeds are full of some noxious chemicals (toxic alkaloids). It is actually pretty amazing that the caterpillars can eat the leaves and survive. Genista caterpillars use the plant’s chemicals to defend themselves, like monarch caterpillars use the toxins in milkweeds to defend themselves. They are specialized to those plants.

Even though everything seems to be changing (the garden is now closed), there’s always hope that we can expect to see genista caterpillars again next year.

Have you ever seen a genista caterpillar?

Bug of the Week: Lady Bugs Need Plants

March 25, 2020 / Roberta / 0 Comments

it is another case of “if you plant it, they will come.”

Right now the common desert shrubs called brittlebush (Encelia farinosa) are in full flower.

Many pollinators use the flowers as a source of nectar and pollen, including honey bees, butterflies, and flower flies.

In addition to the dainty little flower fly on the right, this flower has another visitor, an easily recognizable one. It is a lady bug, or more accurately lady beetle, of course.

Many of the flowers had lady beetles sitting on them. Why?

It is well known that lady beetles can supplement their diets with flower pollen, but these plants also offer something else.

Aphids!

Lady beetles are mostly aphid specialists. The larvae eat many aphids per day. The aphids feed on the brittlebush, which in turn feed the lady beetles.

The plants actually support two kinds of lady beetle. In the above photograph is the seven-spotted lady beetle, Coccinella septempunctata. Common in Europe, it was introduced to North America in the last century. As the name suggests, it has seven black spots on its forewings.

The species we encountered first is the convergent lady beetle,Â Hippodamia convergens.Â Native to North America, you can tell these beetles by the two “converging” white lines on the back of the thorax.

The number of spots on the wings of convergent lady beetles varies a lot and sometimes the spots are tiny/nonexistent like on the beetle in the photograph above.

Now you are an expert, can you figure out what species of lady beetle is featured in the header of this blog?

Â Where did the lady beetles come from?

Lady beetles migrate.

Aphids are cool season insects, so here in the low desert they arrive in late winter and early spring. By summer the aphids are gone and so are the lady beetles. The beetles fly into the mountains where they may complete another generation and/or form large aggregations to overwinter. When temperatures begin to warm, they fly back to low lying regions to start the cycle again.

The bottom line is that without the brittlebush and without the aphids, we wouldn’t see lady beetles.

Are there flowers in bloom where you live?

Preschool STEM Story Time: Reptiles

March 19, 2020 / Roberta / 0 Comments

In another in our series of STEM story times, let’s explore reptile-themed books, learning centers, and activities.

The Books:

To start story time, I began by reading an older picture book from my bookshelf, Lizard in the Sun by Joanne Rider and illustrated by Michael Rothman.

Although this book works well when read one-on-one, it was a bit long for a group of preschoolers. They began to distract each other.

After talking about what reptiles are and visiting the activity stations, we finished with their choice from a pile I provided, Get to Know Gila Monsters (Get To Know Reptiles) by Flora Brett.

STEM Activity Station 1. Lizard in the Sun (Under a lamp)

Explore the concept of “cold-blooded” or ectothermic (having a internal temperature determined by-and-large by the external environment.)

Gather:

Two lizard shapes cut from black construction paper
Small desk lamp

Place one lizard shape directly under the lamp and one at least three feet away, preferably in a shaded or dark area. Have the children compare the temperature of each.

(Older children could record the temperature difference with a thermometer.)

Optional:Â Added graphic of temperature vs. lizard activity on page 3 from Sonoran Desert Museum’s Leaping Lizard’s handout.

STEM Activity Station 2. Box of Reptiles (Sorting activity)

Gather:

- - Toy or model reptiles:Â snakes, alligators, lizards, turtles
  - Box or bin
  - A few toy or model animals that are not reptiles:Â mammals, birds, insects, fish, or frogs

Mix the animals in the box or bin. Prepare a sign that reads:Â Some animals were put into the box of reptiles by mistake. Can you find the ones that aren’t reptiles and take them out?

STEM Activity Station 3:Â Senses Learning Station

Gather:

Images of snakes with prominent heat sensing pits (sense heat)
Images of snakes tongues and Jacobson’s organs (smell)
Point out the eyes (sight)
Hearing- although reptiles don’t often have obvious ears, they can hear

Place this station near the lizard in the sun station so can compare how we detect heat with how a snake detects heat.

(I included this station because we had previously learned about human senses).

STEM Activity Station 4:Â Make a macaroni snake craft (fine motor skills)

Gather:

Chenille stems (pipecleaners)
White glue
Pasta shells
Penne (red lentil for color)
Marker
Red craft foam cut into tongue shape (Y)

Make a loop in one end of the chenille stem to form the head. Feed the penne onto the chenille stem to cover the body. Bend the end back to hold the penne on. Add eyes to a pasta shell and slip over the head loop. Glue into place (do this after the body so it doesn’t get dislodged). Glue on the tongue. Allow glue to set before playing with the snakes.

See our previous snake craft using paper beads and a more detailed pasta version at The Pinterest Parent.