Aphids
Groups of aphids are found on new plant growth. Their feeding results in leaf
curling or puckering. Aphids can also damage flowers. Thier white, cast skins and
honeydew secretions are signs of infestation. Most Aphid species are identified by
their plant hosts, for example, the Crape Myrtle Aphid and Podocarpus Aphid. Aphids
are less than 1/4 of an inch long. Females give birth to live young during most of
the year in Florida and they produce eggs when temperatures are cool. Aphids can
cause serious plant damage and are easily controlled. Thier honeydew is often a
source of food for beneficial insects.
Overview
- Latin Name:
- order Homoptera, Family Aphididae
- Appearance:
- Aphids contain sucking mouthparts called stylets. They are soft bodied;
long thin legs; two-jointed, two-clawed tarsi; and usually a pair of cornicles,
abdominal tubes through which a waxy secretion is exuded. Aphids have two compound
eyes and two ocular tubercles made up of three lenses, each of which is located
behind and above the compound eyes. Female aphids can produce winged offspring
to spread from heavily infested or dying plants.
- Habit:
- Aphids tend to feed in clusters and generally prefer newer, succulent shoots
or young leaves on plants.
- Diet:
- Many, but far from all, aphids are monophagous (i.e. feed on only 1 species
of plant). They tend to feed passively on sap of phloem vessels in plants. As
they feed, aphids often transmit plant viruses to their food plants. These
viruses can sometimes kill the plants.
- Reproduction:
- Aphids have an unusual and complex life cycles which allow them to rapidly
create massive populations in a short periods of time. Most species during winter
months leave fertilized eggs glued to stems or other parts of plants. Nymphs
hatch from these eggs become wingless females known as stem mothers. With no males
present, Stem mothers reproduce parthenogenetically (without mating) and keep
their eggs are held within their bodies until they hatch. All offspring are
females soon mature and begin to reproduce in the same manner. This pattern
continues for as long as conditions are favorable. In autumn and as temperatures
cool, a generation of aphids appears that includes both males and females. After
matting, these females lay the fertilized eggs which hatch into new stem mothers
the following spring.
- Control:
- While control can be easily established with various insecticides, Natural
enemies play an important role in controlling aphid populations. Insects like Lady
beetles, lacewings, damsel bugs, flower fly maggots, certain parasitic wasps,
birds, and fungal diseases all attack aphids and keep their populations in check.
Homeowners should avoid unnecessary use of over-the-counter insecticides which
are harmful to beneficial organisms.
- Detection:
- Unhealty or stunted plants and plants with curled or deformed leaves are
likely to have aphid infestations. Feeding aphids usually clusters on succulent
shoots, under leaves, or other suitable feeding sites on the afflicted plant.
The presence of honeydew or sooty mold is an excellent clue that aphids are
present. Examine your plants closely to detect aphids before damage is evident.
- Evolution:
- Aphids probably first appeared around 280 million years ago, in the
Carboniferous period. They probably fed on plants like Cordaitales or
Cycadophyta. The oldest known aphid fossil is one of the species Triassoaphis
cubitus from the Triassic. At that point in time, there existed relatively few
species of aphids and the number of species increased since the appearance of
angiosperms 160 million years ago that allowed for speciation to occur and give
rise to specialized aphids. Aphids have also changed apperance with Organs like
the cauda or the siphunculi that did not evolve in the species until the Cretaceous.
