There are around 18 species of ladybird beetles in Ontario, all of which feed on aphids and mealy bugs. However, Harmonia axyridis was considered very effective in eradicating the pest problems associated with crops such as soya. Hence it was introduced into USA and thus entered Canada. Here is an account entailing general information and observations on this beetle.
|Asian Lady Beetle showing the "W" mark on it's pronotum|
|Photographed at south shore of Lake Huron during Summer|
There are several successful cases of biological control of pest population by exotic species. One of the cases is, in which the cottony cushion scale insect – a pest on citrus trees, was the reason for major loss of the Californian citrus industry. A vedalia beetle and a parasitoid fly were then introduced from Australia to control the pest population. After a few years, the pest was completely controlled by these exotic predators. And the availability of food, in this case, the scale insect, determined the population density of the exotic predator, thus controlling its invasiveness.
|Aphids are hemiptera bugs, feeding on plant sap. |
They reproduce extremely rapidly and thus expand and
exploit the food sources available, including crops. Photographed in India.
“Adults feed on grapes in the late fall for sugars to survive during hibernation. However, they get harvested along with the grapes. When crushed with the grapes they impart a musty odor to juice or wine. The odor is because of a compound called methoxypyrazine, which is a stable compound and resistant to heat, fermentation and filtering. ” Timothy E. Martinson et al, The Buzz on Asian Lady Beetles
“Houses – particularly light colored ones – look like rock faced cliffs to lady beetles in the fall. This has been a minor problem in Central NY since the mid 90s.” Timothy E. Martinson et al, The Buzz on Asian Lady Beetles
|Five different morphs as seen during the invasion|
|Two sleepy beetles at my home|
So, after a long winter sleep, the ladybirds rise up and go on a search for mates. This happens during spring time. That’s the time when they congregate again and invade homes – actually, to seek shelter for mating. Thus be the life of these beautiful, yet invasive Ladybirds – Harmonia axyridis.
1. Timothy E Martinson, The Buzz on Asian Lady Beetles, Finger Lakes Vineyard Notes #8, August 12, 2002
2. Kevin W Ker, Questions and Answers about H. axyridis (Pallas), April Harmonia axyridis Seminar, 2002
3. Kevin W Ker, Multicolored Asian Lady Beetle – New Insect or just Overlooked in Ontario
4. Catherine R Weeden et al, Biological Control: A Guide to Natural Enemies in North America
5. Caltagirone, L. E., Doutt, R. L. The History of the Vedalia Beetle Importation to California and its Impact on the Development of Biological Control