Friday, June 26, 2009
A Bug Eat Bug World
Aphids, small members of the insect order homoptera, eat (or drink, I guess) plant sap. They can be quite the garden pest, but they're fascinating -- they come in many shades of red, orange and yellow, as well as the less exciting green, black and white. Aphids don't chew; rather, they pierce plant flesh and sip as though through a straw. They have cornicles -- tubes which come out of their abdomen -- which emit a defensive waxy substance. (Aphids also produce honeydew -- sticky-sweet drops of left-over sap which can leave little dots all over cars parked under infested trees.) They are pear-shaped and slow-moving... which is OK. Most aphids don't go very far in their lives, staying right on the stem where they began life! These aphids are flightless, but when a plant gets too crowded, some flying aphids will be born. These pioneers leave to start colonies on new plants.
For part of the year, female aphids give birth to live young. Beginning in the spring and early summer, only female babies are born, which grow through the warm parts of the year. Later in the summer and fall, males are finally born and mate with the females. This late-season generation lays eggs, which will hatch in the spring. Live aphids do not survive the winter.
That aphids reproduce quickly is bad news for gardeners, but good news for carnivorous insects. Among many others, ladybugs eat aphids, and so do lacewings. And lest you be worried that you don't see that many lacewings around, know that each one can eat 200 aphids a week!
Another interesting aphid interrelationship involves ant farming. Some ants will protect colonies of aphids on their host plants, and live off of the carbohydrate-rich honeydew that is produced. These ands will actually stroke the aphids' antennae, causing the honeydew to be secreted. This mutualistic relationship is a win-win -- the ants get their food and the aphids get protected. The plant is the only loser.
Speaking of carnivorous insects, (which I was, a while ago) my yard is lucky enough to be host to many varieties of odonata (my favorite!!!) despite the lack of pond or other water. Perhaps they come due to the high mosquito population. Anyhow, I rarely get to photograph them because they have the pesky tendency to move. Fast. But I caught this beautiful bright green pondhawk (I think) resting last night.