I can use a sextant, make a cheese soufflé, and photograph snowflakes through a homemade microscope, but I can’t outsmart an aphid.
Aphids are clever pests, hiding under zucchini leaves to avoid getting sprayed with my homemade concoctions. They are globetrotters, too, migrating worldwide by riding on the wind and stowing away on plants traveling to far-flung ports.
Did I tell you that aphids are camouflage experts? They appear in rainbow colors including lime green, pink, black, brown, red and almost colorless.
Aphids, also known as plant lice, are among the most destructive insect pests in temperate regions.
Do you find aphids in the desert? Hardly.
These small sap-sucking insects have soft bodies that cannot survive in a hot, dry environment. But that doesn’t mean their numbers are suffering, for about 250 species in the Aphidedae family are serious garden, agriculture and forestry pests.
Recently, complaints from local gardeners raising crops in low tunnels, hoophouses and greenhouses tell me it’s time to increase our understanding of this tiny pest.
Cucumbers, tomatoes and zucchini love the warm and cozy environment within these protected enclosures. Alas, so do aphids.
Aphids have deplorable table manners, feeding themselves through sucking mouthparts called stylets. It’s a passive feeding process, whereby they simply step up to the feeding trough like a bear does when fishing for salmon at Brooks Falls. They puncture the phloem vessels in plants and simply ingest the sap, which is under high pressure. What goes in, must come out, and in the case of aphids, the incoming liquid is released in the form of honeydew, a sweet, sticky substance that is deposited on leaves and flowers — anything in firing range.
For the most part, aphids are crawling insects, but when a host plant begins to suffer or conditions become crowded, some aphid species produce winged offspring that can fly to other food sources.
Speaking of food sources, many aphid species are monophagous, that is, they feed on only one plant species. Others can feed on hundreds of plant species across many families (not good news). That explains why Heather Johnson was alarmed when her daughter stepped into the hoophouse the other day, covered with aphids.
“I had to immediately de-bug my daughter,” Heather explained. “She’d been playing in the alder bushes, which I knew were thick with aphids. And the scary thing is, it only takes one.”
Yes, aphids have amazing means of reproduction, ranging from simple to complex. Some species have both sexual and asexual reproduction, creation of eggs or live nymphs (as in giving birth to live young). Here’s how live birth works: Overwintering eggs hatch in the spring in females. Through a special process called meiosis, the eggs are genetically identical to their mother. This process occurs throughout the summer, producing multiple generations that live about 30 days. Thus, one female hatched in the spring (remember, it only takes one) may produce thousands of descendants.
I won’t go into details of the other cycles, except to say that when the cooler temps of autumn arrive, aphids can undergo another sex change so there are males and females which produce eggs that can overwinter in a greenhouse.
The tidbit about overwintering is important for those who wish to keep food production going as long as possible into the winter or don’t bother to conduct a thorough, end-of-the-season cleaning of the hoophouse or greenhouse. Either way, you risk supporting an aphid infestation the following spring and summer.
While it all sounds like bad news, you can’t help but appreciate a creature whose survival depends on its ability to be so adaptable. I mean, think of the people you know who refuse to adapt to changing conditions and make themselves, and everyone around them, miserable.
So here’s another reason to be aphid aware: As aphids feed, they often transmit potentially damaging plant viruses.
Think about it. You have potatoes growing in a raised bed near the greenhouse window or door. On sunny days you open the greenhouse window to increase the airflow for the tomato plants growing inside. An aphid, hanging out on a potato, decides to move on since the feeding trough on the potatoes is getting a bit crowded. So it grows a set of wings and, sensing nice warm air coming from the open window, buzzes its way across the sill and lands on a juicy tomato leaf.
“I’ll fix that,” you say, by putting screens on all openings to the greenhouse. But then you block the bees and other pollinators from accessing your greenhouse plants. No pollinators, no veggies — and one of the main reasons for self-pollinating varieties of zucchini and cucumbers.
Marion Owen can be reached at 486-5079 or firstname.lastname@example.org. Archived copies of weekly garden columns and an RSS feed can be found at www.kodiakdailymirror.com. “Kodiak Growers” are now on Facebook.
How to outsmart an aphid
Plants showing aphid damage can have a variety of symptoms, such as stunted growth, mottled or curled leaves, browning, wilting and death.
And just as there is a variety of symptoms, there is a variety of cures. Fortunately, many plant extracts and other liquid solutions are just as effective and much more eco-friendly than chemical counterparts.
• Neem products, soap sprays and homemade potato (or tomato) leaf sprays are effective in the war against aphids.
• Aphids are drawn to new growth and succulent growth, so pay attention to new shoots and avoid feeding your plants too much nitrogen, which produces overly succulent (juicy) leaves.
• Respect an aphid’s natural enemies, such as hover fly larvae.
• Keep the fans running in the greenhouse.
• Check your indoor plants every day.
It’s only by understanding your enemies that you can outsmart them. And like anything else in life, it’s a journey.