If you see an insect that looks like a small alligator on one of your plants, might you need to go in to remove it, squeeze it out, or spray it? You're probably seeing beetle larvae, one of the gardener's best friends.
The ladybug is a "natural enemy" of aphids, scale insects, spider mites and other harmful insects. "Natural enemy" means that you don't need to spray to get rid of these pests, because the ladybugs will take care of the problem for you. In fact, spraying may do more harm than good because it will likely kill the natural enemy known as the "beneficial insect," allowing harmful insects to reproduce more quickly.
We all know what an adult ladybug looks like, but even experienced gardeners may not be familiar with what a ladybug looks like in its most expensive and mysterious form. This is important information because one insect can eat up to 5,000 insects during its lifetime. The larvae are elongated and pointed, with six legs. They are black, dark brown or dark gray with orange or yellow spots.
The larval stage of the beetle feeds primarily on aphids and is most common on plants with aphids. Most rooted plants can tolerate aphids. If you feel the need to reduce the number of aphids on your plants, you can kill them by shaking the plant or spraying it with a strong stream of water. Since ants protect aphids from natural enemies, keeping them away from plants helps the beneficial insects do their work.
Insects are also called in Europe "beetles" or "beetles." Like other insects, beetles go through complete metamorphosis through the egg, larva, pupa, and adult stages. Adult beetles lay hundreds of eggs in about two months. The eggs are elongated and often yellow or orange. They are placed on the underside of leaves in groups of 10 to 30 in colonies of aphids and other herbivorous pests. The larvae hatch within a few days and begin feeding once the eggs hatch. The larvae grow rapidly and shed their skin several times. When it reaches a maximum size of ⅓ inch, it attaches a leaf to its tail, forms a hard shell, and enters a resting stage called a cocoon. The pupation stage lasts one to two weeks and then the adult beetle is ready to eat more aphids.
Beetles are most active from spring to fall and will not fly if the temperature is below 55 degrees. Playback stops when the length of the day becomes shorter. Development from egg to adult takes approximately six weeks during the growing season. The beetles typically overwinter as adults in protected areas such as buildings, ground covers, or tree trunks. Its version of hibernation is called lag. They can have five generations a year.
Besides unsuspecting gardeners, ladybugs' main predators are birds. Insects are also preyed upon by frogs, bees, spiders and dragonflies. Although adult beetles are considered red with black spots, they can come in many colors, including black, yellow, and gray. It may contain square or irregularly shaped stains, or it may contain no stains and be scratched.
Insect provided the first very successful use of biological or "natural" control through the importation of beneficial insects. In the late 19th century, the vidalia beetle ( Rhodolia cardinalis ) was introduced to the United States to control cotton scale, which was extremely destructive to citrus trees. The insect was very effective. Insects were also brought to the Galapagos Islands to reduce cotton scales, where they were also useful.
To repel enemies, ladybugs can release a smelly chemical from their "knees." Predators avoid eating insects after learning that the bright orange, red and black color combination can cause an unpleasant taste. Even non-venomous insects imitate the colors of poisonous insects to protect themselves from predators.
Purchasing ladybugs and releasing them into your home garden may not be an effective pest control method. In many cases, the insects are flying or are not healthy enough to survive due to the way they are captured. However, it is easy to attract ladybugs to the garden with a combination of pollinator-friendly plants, limited use of pesticides, and feeding them some aphids. In the absence of insects, a strong stream of water is often the most effective way to reduce pest numbers.
Attention winemakers: There are nearly 5,000 species of beetles, including about 175 species that live in California. The Asian beetle, a species found in California, feeds on late-season grapes and can contaminate wine if its odor accumulates with the fruit.
In many places, ladybugs are considered a sign of good luck. In England, finding an insect means that there will be a good harvest.
Pransky has been a professional gardener since 2012 and has gardened in San Diego for more than 30 years.
Get free gardening tips from UCCE Master Gardeners or the San Diego County hotline at (858) 822-6910 or by email at help@mastergardenersd.org .
