Sand Digger (Hunting) Wasp Friday October 26, 2012
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Sand Digger (Hunting) Wasp

One day I was out walking on my lunch hour, and as usual, I had my camera with me. Casing out the ground as I walked, I noticed something crawling around in the dirt, climbing in and out of small holes. At first, because of the coloring, I thought I had found a spider wasp. This thread-waisted wasp, however, turned out to be what is sometimes called a “Sand Lover” wasp. Instead of hunting spiders to feed to her young, she hunts and paralyzes caterpillars.

Sand Digger Wasp
Digger Wasp (Sand Wasp / Sand Lover) – Ammophila sabulosa

Sand Lover

Ammophia originates from the Greek words ammos – sand, and phillia – lover. This Sand Lover is as gentle as a solitary wasp can be; she rarely stings and lacks the potent venom of social wasps such as yellow jackets or paper wasps. The Sand Lover is better known as “Digger Wasp” because of the way she excavates to make her underground nest.

Sand Digger wasp near nest
Sand Digger Wasp near the entrance of her burrow.

After mating, female Sand Wasps work alone to construct their entire nest and do all of the foraging needed to feed their young. Sand Lovers dig tunnels in soil or sand, up to 24 inches deep, forming underground chambers to lay their eggs and provision the larvae with food.

Digger Wasp
Sand Lover Wasp batting her eyes (well, not really….)

Wasps on the Hunt

Unlike Mud Dauber females who hunt for spiders, Sand Digger wasps prey upon caterpillars, sometimes twice their size! After creating a burrow, the female Digger wasp searches for a pebble large enough to cover the entrance to her nest. She then sets out on a hunt for caterpillars. The mother wasp is able to locate her host by the smell of its frass (insect pooh); she first immobilizes the caterpillar with venom injected into its nerve center, then drags the still-living creature into her underground nest before laying an egg on it.

Digger Wasp with caterpillar
Drawing of a Sand Digger Wasp and Caterpillar
Provisioning the Nest

After she lays an egg, the Digger wasp fills the mouth of the hole with dirt or sand, tamped firm with a pebble and then camouflages the entrance with twigs. The female Digger wasp will make several burrows in her short (two month) life span, the challenge she faces is ensuring her larvae, which are at various stages of growth, have enough food before they reach adulthood.

Digger wasp entering her nest
Sand Digger Wasp entering her burrow

When a larva hatches, it begins to feed upon the caterpillar, avoiding any vital organs so as to preserve the life of the paralyzed caterpillar; this way, the meat will be fresh until the young sand wasp is big enough to leave the burrow.

The Great Golden Digger Wasp
Great Golden Digger Wasp (Sphex ichneumoneus)
Photo by Gary McDonald
(Notice the fur, unlike the smooth body of the Sand Digger)

Digger Wasps are Beneficial Insects

So how can Sand Digger Wasps be beneficial? Although adults feed on nectar from flowers, the female Sand Digger can clear your garden of caterpillars. Her sister, The Great Golden Digger Wasp, hunts crickets, grasshoppers, and katydids to feed to her young. In order to attract these beneficial predators, plant wild flowers, daisy, and umbelliferae – plants with flowers in umbels such as parsley; carrot; anise; caraway; celery; and dill. On the flip side, if you don´t want digger wasps, mud daubers, or even bees, plant less flowers but know that you´ll have a lot more grubs, caterpillars, crickets, and spiders.

Digger Wasp near entrance to nest
Sand Digger Wasp searching for her pebble.

When it comes to pest management, the only time one really needs to be careful of this gentle Sand Lover is if she has decided to excavate burrows in your yard. You may want to watch your step during the summer months, especially if you see holes in the ground about the size of a penny or nickel —-there just might be a mother nearby hunting for caterpillars.

Article, Artwork, and Photos (unless otherwise indicated) by Donna Walker

Note:Special thanks to Gary McDonald for his continuous permission to use his photos for these educational blogs, including the beautiful photo of “The Great Golden Digger Wasp.”

Sand Digger Wasp:

Scientific Name: Ammophila Sabulosa
Family: Sphecidae
Order: Hymenoptera
Class: Insecta

Digger / Sand Lover Wasp References:

Farb, Peter and the Editors of Time-Life Books, The Insects, Life Nature Library (Second Edition), Time-Life Books Inc., Alexandria, Virginia, 1977.
organicgardeninfo.com/beneficial-insects

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