Skip to content

4

This week we were grubbing around in the compost heap when we found this. We were quite excited.

green june beetle grub

It's about the size of my thumb. I can tell it is a beetle larva from the fact it has a hard head capsule (dark brown) and six distinct legs right behind its head. Those small brown circles on its sides are the opening of the airways it uses to breathe. Those are called trachea.

green june beetle grub

I knew what kind of beetle it was when it flipped onto its back and began crawling along upside down. My son said this was “Freaky!” (I think that is tween-speak for “Really cool!”) You can see the legs better. It also has bristly brown hairs. It quickly crawled off, upside down.

green june beetle grub

This interesting critter is a green June beetle grub, Cotinus mutabilis. They are a type of scarab beetle. The larvae (grubs) feed on compost and help with decomposition. They are up to two inches long when mature. Next Spring it will pupate in the soil and emerge as an adult.

The adults have beautiful metallic green wings with brownish-gold at the margins. They congregate in large numbers to feed on various types of soft fruit, which gives them their other common name, figeater beetle. Their normal food in Arizona is prickly pear or saguaro cactus fruit. They also visit our desert willow flowers for nectar.

I only have a photo of a preserved specimen. Don't worry, all of our preserved bugs died of natural causes.

green june beetle

The adults are even shinier when they are alive. Isn't it interesting such a "freaky" larva can turn into such a spectacular adult? Talk about the ugly duckling...

By the way, if this grub hadn't scooted away so quickly, it would probably have been bird food. Grackles love them.

4

The bug of the week is a tiny beauty with an attitude. When I first spotted this bug I thought she might be an ant.

bethylidae wasp

But then I looked again. This insect was just not acting like an ant.  She was climbing around on a plant like she was searching for prey, more like a wasp.

bethylidae wasp bethylidae wasp

She doesn’t look quite like an ant either. Her antennae are not elbowed like an ant’s would be. Bug Guide has some pictures of bethylid wasps that look fairly similar to this one, although I couldn’t find an exact match.

Edit: I guess first impressions were best. Seems this is a Pseudomyrmex ant. Check this photograph of Pseudomyrmex pallidus. Thanks to Cameron for straightening me out.

Bethylid wasps are parasites* of caterpillars and beetles larvae. Even the small ones like this have a potent sting. They use their stingers to immobilize the host larva, and then lay their eggs on it. The wasp larvae that hatch from the eggs use the caterpillar or beetle grub for food. Because the hosts are often pests of crops, these bethylid wasps are considered to be beneficial insects. Just leave them alone if you are lucky enough to see one.

*A parasite uses one host that is bigger than itself for food. A predator catches and eats many smaller prey items for food.

1

We were doing a bit of yard work when we came across this leaf-footed bug. These insects get their name from the leaf-like flanges on their hind legs.

leaf-footed bug

Note the light-colored zig-zag marking across the middle of its back.

Leaf-footed bugs have sucking mouthparts and sometimes feed of fruit such as cactus fruit, oranges or peaches. Although we do have citrus, I think this one is a visitor from our neighbors’ yard. Our neighbors have a pomegranate bush. Pomegranates are one of the leaf-footed bugs' favorite foods.

Like many of their relatives, these true bugs can give off an odor when handled.