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The young, larval form of the
ladybug is often less recognized. They tend to resemble tiny,
six-legged alligators, blue-black in colour with orange spots.
Often, gardeners unknowingly squish or spray the larval form
of the ladybug, not knowing what a benefit they are to the garden.
Both adults and larvae feed
on many different soft-bodied insects but aphids are their main
food source. One larva will eat about 400 aphids during its development
and single adult can eat a whopping 5,000 aphids in its lifetime.
In addition, they will also eat other insects such as mealybugs
and spider mites as well as the eggs of the Colorado Potato Beetle
and European Corn Borer.
Life Cycle
Within a year, there can be
as many as 5-6 generations of ladybugs as the average time from
egg to adult only takes about 3-4 weeks. In the spring, adults
find food and then the females lay anywhere from 50-300 eggs.
The tiny eggs are yellow & oval shaped and are usually found
in clusters of 10-50, near aphid colonies. The eggs take 3-5
days to hatch and the larvae voraciously feed on aphids for 2-3
weeks before they pupate into adults.
In the fall, adults hibernate
in plant refuse and crevices. They often do this en masse where
several hundred adults will gather at the base of a tree, along
a fence row or under a rock. They especially like areas where
leaves protect them from cold winter temperatures.
Attracting Ladybugs in the Garden
Apart from aphids, ladybugs
also require a source of pollen for food and are attracted to
specific types of plants. The most popular ones have umbrella
shaped flowers such as fennel, dill, cilantro, caraway, angelica,
tansy, wild carrot & yarrow. Other plants that also attract
ladybugs include cosmos (especially the white ones), coreopsis,
and scented geraniums, dandelions.
Apart from planting attractive
plants in the garden, you can also promote ladybug populations
by cutting back on spraying insecticides. Not only are ladybugs
sensitive to most synthetic insecticides, but if the majority
of their food source is gone, they won't lay their eggs in your
garden. As difficult as it may be, allowing aphids to live on
certain plants is necessary to ensure that there is enough food
for ladybugs. In addition, resist the urge to squish bugs &
eggs in the garden, unless you're certain that they are not beneficial.
Purchasing Ladybugs
Sometimes, there just isn't
enough room in the garden to have ladybug-attracting plants or
you or your neighbour may have been over diligent with the pest
control. In certain circumstances, purchasing ladybugs can help
to control a severe problem or help a population become established.
Scientists have found that indoor-reared
ladybugs fail to find their own food when released outside so
the majority of commercially available ladybugs are collected
from the wild. Before releasing them into the garden, here are
a few tips to help ensure that they stay where you want them:
1. Only release ladybugs after
sun down or before sun-up. Ladybugs navigate by the sun and in
the evenings & early mornings, they tend to stay put.
2. Pre-water the area where
you are releasing them. Not only will the ladybugs appreciate
the drink, free-moisture on the leaves helps the ladybugs to
"stick" to plants.
3. In the warm months, it helps
to chill the ladybugs in the fridge before releasing them. Ladybugs
tend to crawl more than fly in colder temperatures and the overnight
stay in the fridge won't harm them in anyway.
4. On severely infested plants
like roses, drape a floating row cover or thin sheet over the
plant and release the ladybugs underneath. Within a day, the
ladybugs will have found the aphids and will be happily munching
away at them.
One Note: The Asian Ladybug
If you are planning to purchase
ladybugs for your garden or greenhouse, I encourage you to select
the native ladybugs species, Hippodamia convergens, rather than
the Asian ladybug, Harmonia axyridis. Although the latter is
very effective at controlling aphids and is often the species
of choice for commercial greenhouse growers, it is the main cause
for "ladybug infestations" inside houses.
While the native ladybug is
happy to hibernate outdoors, the Asian species requires warmer
temperatures and often ends up becoming a pest to homeowners
as it congregates in large numbers inside. In addition, it seems
to be establishing fairly large numbers in the wild and there
is some concern it will begin competing with the native species.
Some suppliers of predatory insects do sell both species and
it's best to choose the native one if you can. |
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