The wasp that cleaned out the caterpillars

Before you go thinking that honeybees mentioned in the last post are the reason you have so little caterpillar damage in your Front Range vegetable garden, remember European Paper Wasp. This wasp moved into Colorado in 2000 and has rapidly colonized Front Range landscapes. It is found on the West Slope but not generally in the mountains.

European paper wasps rear their young on live insects. They have become one of the most important natural controls of many kinds of Colorado garden insects. Most commonly they feed on caterpillars, including the larvae of hornworms and cabbageworms in the Colorado vegetable garden. On trees and shrubs tent caterpillars and sawfly larvae are commonly taken prey.

The European paper wasp is a black insect marked with yellow that is commonly mistaken for western yellowjacket. European paper wasp is slim in comparison to the somewhat blunter, more compact body form of yellowjackets. The long hind legs of paper wasps also tend to trail below when the insects are in flight unlike yellowjackets. They do not produce the nuisance problems for outdoor dining that are typical of western yellowjacket.

Check the Colorado State University Extension website for additional information and more photos of European paper wasp.

[European paper wasp photo credit: Whitney Cranshaw, Colorado State University, Bugwood.org]

Bees do more than pollinate

The buzz of bees in flight causes some caterpillars to slow or cease feeding on plants.

German researchers Tautz and Rostas report in December’s Current Biology a 60 to 70 percent reduction in pepper leaves consumed by beet armyworm caterpillars in tented enclosures with honeybees than in tented enclosures without bees after two weeks.

Several caterpillars have evolved freeze-motion or drop-off-plant avoidance behaviors in response to predatory wasps. Sensory hairs on the caterpillars pick up vibrations from flying wasps and trigger the response. These behaviors are often combined with defensive coloration that blends caterpillars into the background color of the plant.

So bees can be beneficial to plants by slowing feeding even though honeybees are not predators of caterpillars. Note that pepper flowers (like those of tomatoes and eggplant) self-pollinate with wind movement, not from visits by bees or other insects.

This may be another reason to plant bee-attracting flowers in your Colorado edible garden in addition to wanting bees for pollinating squash, cucumbers, melons and pumpkins.

[Honeybee photo credit: David Cappaert, Michigan State University, Bugwood.org]

[Beet armyworm photo credit: Frank Peairs, Colorado State University, Bugwood.org]