When spring temperatures are below average the garden tends to be overrun with aphids. A very logical occurrence, larger insects that feed on aphids take longer to mature. As our temperatures rise in May, you may notice larger aphid populations, particularly on roses, iris, and spirea. There are over 4,000 species of aphids, some are black, others white, most are a light green, the size of the tip of a ball point pin. The foliage they feed on usually becomes curled or deformed, a secondary issue since aphids carry viruses which are released into the plant as they puncture the foliage to feed.
There are numerous beneficial insects that seek out aphids, something the gardener is always grateful for. Ladybug larvae will eat a fair share, more so than the adult ladybug. Trichogramma wasps will also parasitize aphids and this happens with great regularity. In order to know if these beneficial wasps have infected the aphids you need only look closely at an aphid colony, always located on a plants new growth. Within the population there will be some aphids that look slightly larger, like they're bloated. This is where the wasps have been working, laying an egg in the aphid, which will hatch and feed on the soft body from the inside out.
Lacewings are a flying insect, about half an inch long. The larvae are big eaters, their favorite food - aphids, so much so that they are commonly known as aphid lions. The tiny eggs of lacewings are held on a fine hair, aloft and away from each other. They are such voracious feeders that this tiny hair keeps them from eating each other, it also protects them from ants.
The adult lacewing feeds on nectar and pollen, as does the trichogramma wasp. If you are interested in attracting more beneficial insects to possibly curtail the coming aphid explosion, consider planting their favorite flowers. The mouth parts of these insects are very small, they need small flowers, close together, to gather the most pollen and nectar.
Many herbs are suitable, especially umbelliferous types. Consider dill, coriander (cilantro), fennel, caraway, lovage, angelica, tansy and mint. Sweet alysum is actually used by vegetable growers to attract parasitic wasps to the fields, planted alongside rows of lettuce.
If you've planted cool season vegetables, let a few bolt. The flowers of lettuce, broccoli, and mizuna are especially good for our little army of aphid eaters. Be observant, patient and forewarned, it might be a real aphid year but the beneficial insects will arrive with a great hunger.
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