A large number of ladybugs appear in Harbin, is it the disadvantage of not burning wheat straw?

As the weather turns cold, many insects have become less active, but these days in Harbin, it has been unusual. An insect suddenly gathered in large numbers and appeared densely, causing local residents a headache.

A netizen made a video collection. From the video, it can be seen that a large number of these insects stay on the outer wall and glass of the house. As for the entire windshield is "exploded" insect corpses.

Since the burning of straw has been banned in many places in recent years, burning straw has a relatively good effect, that is, it will burn the eggs of some pests to achieve the effect of controlling pests.

Therefore, some people suspect that the reason why so many insects appear in Harbin this time is the ban on burning straw, which eventually led to the flood of these insects.

So what exactly are these insects, and why do they suddenly appear in abundance in the fall?

This kind of insect is actually not a rare bug. They are lady beetles axyridis, a kind of lady beetle that is relatively common in northern China. Because of its beautiful appearance, northerners like to call it "Sister Hua".

What is equally as popular as them is their gathering behavior in October every year. If we look at the relevant news now, you will find that there are reports of this kind of ladybug gathering and disturbing people almost at this time of year.

Except for the occasional disturbance, ladybirds are not pests, they are real beneficial insects, the kind that eat pests, and eat themselves abroad.

Africa and the Americas originally did not have this lady beetle, but more than 100 years ago, the lady beetle was introduced to these areas as a beneficial insect for biological control. Today, the rapid population growth has caused headaches in these areas, and they are also It was successfully included in the invasive species database by the International Union for Conservation of Nature (IUCN).

In fact, the reason why ladybugs appear collectively is very simple, that is, they are looking for a place to overwinter, and burning straw will hardly affect their population.

Why is autumn "flooding"?

Most insects are ectotherms, and their body temperature changes with the environment, so they also have a hibernation-like state called diapause, in which insects lower their metabolism to survive the winter.

However, because there are many forms in the life cycle of insects, the wintering forms of different insects are different. Most insects choose to spend the winter in the form of eggs, the second most are larvae, and there are only a few insects. It will choose to spend the winter in adult form, and the lady beetle is one of them.

Eggs have strong resistance and are the best choice for wintering. Larvae can burrow into the ground and various warmer crevices. Adults basically exist for reproduction, so they are rarely equipped with some wintering skills.

However, letting the adults overwinter also has the advantage that they can take over a niche market and reproduce more quickly in the spring and summer when food is plentiful.

Nature rolls very hard, so even if it is more difficult and unreasonable for adults to survive the winter, there will still be many insects to choose this way.

In fact, the growth and reproduction cycle of lady beetles can basically avoid the time period when we burn straws.

In North China, the lady beetle begins to reproduce from the burrow in March. It can produce six generations a year. The average time from egg to adult for each generation is only 25.12 days, and then all individuals overwinter as adults.

Generally, the time for burning straw in the north is autumn and spring, and the time is concentrated and short. At these time points, the lady beetles are basically living in the adult state, and it is easier to escape. It can be said that burning wheat straw has more impact on them. Small.

What really makes them seem to be flooded is that they like to gather together and share wintering sites, so it is not actually flooding, but it seems that there are many parts.

In addition, this kind of seemingly flooded disaster has not happened in the past few years. The collective appearance of lady beetles has existed since ancient times, but now there may be fewer natural enemies, and each time there may be more occurrences Just a little.

Axychromis ladybugs that appear collectively are pests

Any creature capable of such a collective mobilization is not simple, and scientists have been trying to decipher what allows them to do so.

Some previous studies have found that adult lady beetles secrete aggregation pheromone to send signals and locate each other, and finally gather together in large numbers.

More critical than volatile pheromones, though, is now believed to be their visual role. These ladybugs seem to prefer to gather with each other through visual cues, and it is the illuminated surface that attracts them, which may be why they often Maybe it's because of the collective appearance on the wall of the house.

Although the lady beetle is a beneficial insect for agriculture and forestry, if it appears collectively in this way, the impact is still relatively large.

First of all, they bite, and if they accidentally land on us, they may feel that we are encroaching on them and bite us.

Second, lady beetles, like many insects, use methoxypyrazine as a defense chemical to prevent predation.

These unpleasant chemicals are stored in their hemolymph at much higher concentrations than other ladybugs, and they reflexively release these chemicals when they are stressed, and if they are trampled to death, they will release all.

So they stink, especially when they appear in groups, and even if we don't do anything threatening to them, there's a strong smell of dead leaves that some people are allergic to.

Under normal circumstances, when the temperature is lower than 10 °C, this insect will basically have no ability to move, so if you are really troubled by their concentrated winter, you can try to deal with them after the temperature has dropped a little.

at last

In the past, burning straw may indeed have the effect of controlling pests, but now the agricultural pest control has been very diversified, and the disadvantages of burning straw must be higher than the benefits it brings.