Joshua Tree National Park

Over the weekend I took a class on the insects and other arthropods of the Morongo Basin. Much of the class was held at Joshua Tree National Park, but we also visited the Morongo Preserve and the Coachella Valley Preserve.

Along the trail to Barker Dam we came across fresh bighorn sheep scat and tracks, but where are the sheep?

There they are, way up on the rocks high above the dam. We ended up seeing two ewes and a ram .

These acorns are the fruit of the scrub oak trees we saw along the trail.

If the acorns are the fruit then what is this?

This is a gall. Small insects, usually small wasps lay an egg on the tree, and inject chemicals as well that cause the plant to create a gall. The gall provides a house for the larval insect and some food as the larva develops.

This is a gall on a creosote shrub. Many plants make galls in response to insects laying eggs on their stems or leaves.


These dark lines along the stems often appear on more mature creosote shrubs. They are made by a type of scale insect. Native Americans would scrape the sticky secretion and use it as a glue.

This beautiful wasp (Scolia dubia) was getting nectar from the flowers.
This is a Mormon metal mark butterfly on a California buckwheat which is the food plant for its larva .

Dragonflies often land on shiny car parts. Why? Maybe they see the silver shiny surfaces as looking like water.