Garden Friend - I thought you might like to read my recent garden article that ran in The Denver Post about summer garden insects good and bad.
Link to The Denver Post article, click HERE. The full article is below.
How to identify common Denver garden pests - but some insects provide natural pest control
In late August, there is a vast assortment of insect action in our gardens, and it is worth a listen and a watch to see what is happening.
The cicadas are unmistakable with their daily continuous choir of crooning. There are also insects, bugs and spiders afoot, and depending on your barometer for squeamishness, it is not a bad idea to consider whether the crawler or flyer is worth a swat, the spray of death or a free pass to carry on. Walk with me in my garden clogs to see some of the live action and learn how to manage your visitors.
A metallic green bee stands out in any buzzing crowd. I first noticed its iridescent qualities in June and most of the summer. A quick lookup in the book “Garden Insects of North America” by Colorado State University Emeritus entomologist Dr. Whitney Cranshaw confirmed it is an Agapostemon spp. bee. Its common name is sweat bee, although these particular green bees are more focused on gathering pollen and nectar from many garden plants in bloom than from perspiring gardeners.
Fortunately, this good-looking bee slowed down a bit on a coreopsis flower for me to snap a photo. They are ground nesting bees and dig deep nests in areas with flat or sloping soil, and can be solitary or nest in underground communities with other Agapostemons. No swatting or spraying is needed, because this is a good bee, a welcome insect in any garden.
On first glance, I thought this next bug seemed like it might be a good bug — perhaps a predator of an insect that was chewing a plant that shouldn’t be chewed. I was hoping he liked grasshoppers. He wasn’t camera shy while resting on the side of a patio container.
A photo text to a couple of garden friends led to the correct identification. He wasn’t a good guy assassin bug, but rather a bad guy leaf-footed bug (Leptoglossus clypealis) that was probably nibbling on some nearby developing tomatoes. If you check out this fact sheet from The University of California, ipm.ucanr.edu/PMG/PESTNOTES/pn74168.html, you will see photos of this nuisance bug in all life stages. I know without a doubt I’ve seen leaf-footed bug eggs and nymphs in our garden. I’m not too worried about ongoing fruit damage, but I’ll keep an eye out for group feeding and be ready to squish them on sight.
Joining in the musical insect summer chorus are impressive, broad-winged, bright green katydids (Microcentrum rhombifolium). Males use their forewings as instruments to make low, raspy trilling and clicking sounds nightly to attract a mate or stake out its territory.
The traditional katy-did-katy-didn’t hum is more common to East Coast katydids. When found in Colorado gardens, usually on foliage that blends so well with the katydid, a second look is needed to confirm these two-inch, tall-bodied distinguished insects. Their camouflage helps them hide from predator birds, bats, other insects and rodents.
If you find one, just admire it and consider katydids another insect of nature’s fine creation that just wants to chew on plant leaves (without causing too much damage) and live for a while. Read more about Colorado katydids at webdoc.agsci.colostate.edu/bspm/Hexapoda%20(Insects)/Broadwinged%20Katydid.pdf.
Without a doubt, the fast-moving quarter-inch spotted cucumber beetle pest caused distress to my summer yellow squash plants and me a couple of years ago. They just appeared one day in mid-summer and decided not to leave, multiplying faster than adult Japanese beetles on grapevine leaves. I had difficulty controlling them with organic sprays.
Following that, my hair pulling led to pulling the plants entirely because they were feeding everywhere on the plant leaves, petals, fruit and pollen. Spotted cucumber beetles can feed on several different crops including cucumber, muskmelon, watermelon, pumpkins, squash and gourds.
It is important to clean up garden plant debris every fall so there aren’t places for pest insects to overwinter. Also, rotate crops and use floating row covers to keep pests out early in the season. However, remove the cloth when flowers are in bloom to allow them to be pollinated.
There are cucumber beetle and other cucurbit-resistant varieties to plant, so do your homework when purchasing seeds — pest resistance should be listed in the description or on the package.
Every gardener eventually learns that ladybugs, also called lady beetles, are wonderful insect friends to have and protect in the garden. Their black spots vary in number depending on variety and their wing covers vary from bright orange to red. More than 80 species of lady beetles are found in Colorado, of which 70 are native. A single lady beetle can consume thousands of pest aphids, scale insects, mites and pest eggs in its brief lifetime. With their chewing mouth parts, both the adult and larva (or grub) life stages are beneficial as predator insects.
For lady beetles to find your garden, there needs to be pests for them to consume, so naturally there can be a lag time from when pest outbreaks occur to when they show up and start devouring the pests. The best advice is to live with the brief period of aphid outbreaks until they show up. Use a heavy spray of water on the aphids until the beetles arrive.
Learn to identify lady beetle life stages too. In their larva or grub stage they can eat scores of aphids in an hour. Larvae resemble miniature black-red or black-orange alligators. They look rather mean, but they are do-gooders for pest control so keep them around all summer. Lady beetles also feed on pollen and nectar, especially before their winter hibernation, so grow plants with small flowers like dill, yarrow and butterfly weed for them to easily access. Learn more at extension.colostate.edu/topic-areas/insects/lady-beetles-5-594/.
As with most pest and disease concerns in gardens, the first step is to identify the problem and thoroughly work out the best solution. Many issues can be resolved without any intervention. Sprays, even organic ones, often have unintended consequences and can harm beneficial insects and pollinators along with the pests.
There is generally a natural balance between pest and beneficial insects. Unfortunately, pest insects that normally do not live in Colorado, but somehow make their way here, thrive without natural predator insects to keep them in check, often resulting in serious plant damage and losses. The emerald ash borer and Japanese beetles are prime examples — but that’s a topic for another article.
Betty Cahill speaks and writes about gardening in the Rocky Mountain Region.
