Aphids may look soft but they are not without their own defences. They will put up a fight before being eaten.


make a cocoon at the exit to the ants’ nest and fly away after metamorphosis. Honeydew, which we abhor when it


gets all over our possessions and hands, is also highly prized by a certain conif- erous forest bee, which collects honey- dew to make forest honey. Suck and flow


We think of aphids as sucking insects


and they do act as suckers on occasion, but mostly they simply stick their needle- like mouth parts into the phloem of a plant and let the sap flow – well, actu- ally, it veritably gushes into their mouth parts and through their digestive tract, coming out the other end as honey dew. The sucking part happens when they


tap into the xylem sap of the plant. The xylem cells transport water and minerals upward on the plant. This sap contains only 10 per cent as much carbohydrate and amino acids as the phloem sap, which transports recently manufactured sugars to parts of the plant, including the roots that need them. So why do the aphids go to all this trouble? Some think it


is to balance their moisture


content, but others believe that it has something to do with their ability to reproduce. Still others say it reduces the osmotic pressures caused by the phloem sap gushing into their stomachs. Among the 4,400 species in 10 fami-


lies of aphids, there is an aphid for every plant. Sometimes aphids specialize with just one plant on their menu; some- times


they alternate between plants,


often starting off on trees and shrubs in springtime and moving on to herba- ceous plants as they grow. Sometimes, as with the green peach aphid, they are not fussy at all and will latch onto just about any plant. Aphids come in sizes ranging from


one millimetre long to 10 millimetres long, and in colours that include green, brown, black, pink, grey, red and trans- parent.


Aphid defences Aphids may look soft but they are not


without their own defences. They will put up a fight before being eaten, kick- ing their attackers with their hind feet. Some have spiny backs that make them unpleasant to eat and others have thick skins that make them tough. They can also send out pheromone


alarm signals to warn nearby colonies that there is an enemy at hand. Unfor- tunately for the aphid, some ladybugs have figured this out and use the signal to their own advantage. Aphids have two little venting organs


called cornicles in their third segment that they use in their defence to emit a waxy substance to clog attacker mouth parts. The wooly aphid covers itself in this substance as a long term strategy. For a long time, people thought that the cornicles were where the honey- dew came from, but we now know that honeydew is just plain aphid poop. Some aphids create leaf galls as a defence. They hide inside these waxy


S


ome plants, such as petunias, are just


sharp end of a garden hose. Here are some additional


tools


urge aphids to leave (or die!). Garlic spray


3 cloves garlic, minced 1 tsp. cayenne pepper 1 quart water 1 tblsp. liquid dish soap


Steep garlic, water and cayenne for


24 hours. Strain and add the dish detergent. Spray both sides of the


www.localgardener.net to help you


Homemade aphid fighting recipes too delicate to handle the


Tomato leaf spray


1 to 2 cups tomato leaves, chopped 4 cups water


Steep the chopped tomato leaves in 2 cups of water overnight. Strain and add the remaining 2 cups of water to the liquid. Empty all into a sprayer and spray both side of the leaves (be sure to get the underside where the aphids like to congregate) and stems.


Ant having a feast of honeydew. Home and Gardener Living • 19


houses and venture out, sending out burly soldier aphids produced by the females to sacrifice themselves in protec- tion of the clan. Finally, although aphids are generally


wingless, they will produce a genera- tion of “alates”, aphids with wings,


if


the food runs out. Vulnerabilities, enemies and your defences


Aphids are vulnerable to late frosts,


excessive heat, and pounding rain (and your garden hose). The rain or hose knocks them off their perch and stops them from flying. Their enemies include ladybugs,


hoverfly larvae, parasitic wasps, certain caterpillars, aphid midge larvae, crab spiders, lace wings, certain types of fungus on certain types of aphids – and, of course, hose-wielding humans. They are sensitive to neem oil and


lantana products and to garlic mixtures as well as insecticidal soaps. Some gardeners swear by diatomaceous earth as a cure and a prevention (you can safely mix it with water and spray the leaves, top and bottom). Spraying trees and shrubs with


dormant oil in spring suffocates over- wintering eggs. Banding trees with Tanglefoot and insulation will help keep aphid-herding ants away. Washing trees in early spring and summer can also help dislodge first the eggs and then the nymphs and adults before they move on to your plants. h


leaves and stems. Recipe keeps for one week in the refrigerator.


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