Some time ago, we introduced an important leaf-eating pest on current citrus, the leaf-deep beetle. After the tweet came out, I received feedback from many fruit grower friends, all of whom said that this insect has indeed occurred more in recent years.
However, among them, there is a set of pictures that caught our attention, let's take a look at the pictures first.
The above is the picture transmitted by the farmer, the message forgot the screenshot, the meaning is that our "latent leaf armor" is more serious, the leaves are chewed clean is a hole, the worms are drilled out!
Cough, actually... This is not a leaf-dwelling beetle, but another leaf-eating beetle on citrus, the malignant leaf beetle (larvae). The destructive power of citrus shoots, especially spring shoots, can cause the leaves to be missing, blackened and scorched, and fall off.
About malignant lobular nails
Malignant leaf beetles belong to the order Coleoptera and insects of the family Pterodactycetes, which generally occur 3 generations a year, with the first generation (at the time of spring) being the most harmful.
Adult: Nearly oval, about 3 to 4 mm, bluish-black, yellow-brown feet and abdomen.
Larvae: black head, yellow-green translucent body color, body length 6 to 7 mm. However, when we see it in the field, it is often the right side of the picture, that is because the larvae of the malignant leaf beetle can secrete mucus on the surface of the body (the gray-green part is their feces), so some places also call them yellow slippery cows, yellow slippery worms and so on.
Eggs: The female will lay her eggs at the tip or margin of the young leaf, before biting out the egg laying hole, which is oblong and changes from white to yellowish brown as the incubator approaches.
Harm of malignant leaf beetles to citrus
After the citrus spring shoots are pumped, the overwintering adults begin to move, they will gather together to feed on the young leaves, often eating the leaves into missing holes and holes, or eating the dorsal epidermis and leaf flesh, leaving only the surface waxy layer.
Some flower utensils and young fruits will also be brutally poisoned, especially after the young fruits are damaged, they will be bitten into holes and blackened and fall off.
The hatching larvae feed on the young leaves in clusters and secrete mucus and excrete feces on the back, contaminating the young leaves and causing the leaves to become black and fall off.
Mature larvae can climb under the trunk and pupate in lichen moss, trunk cracks and shallow soil, and the subsequent 2 generations are not harmful.
Integrated control of citrus malignant leaf beetle
This insect is similar to the latent leaf beetle in terms of control methods, and should mainly start from reducing the base of the insect mouth, shortening the time of new shoots, and using drugs to prevent insects and protect the tips in a timely manner.
(1) In winter, cleaning the bark of tree trunks, eradicating weeds, lichen moss, turning soil, etc., destroying the wintering place of malignant leaf nails, and using stone sulfur compounds in winter garden clearance have certain effects.
(2) Remove the damaged branches and leaves of the tree in time during the growth period, remove the ground leaves in time, plough the soil in the summer, and kill the larvae and pupae in the soil.
(3) Foliar spraying of phosphorus and potassium source banks in the spring shoots to help the leaves turn green and mature to shorten the time of damage, if the citrus leaves are not ripe, it is bound to bring convenience to the infestation of diseases and insect pests.
(4) Using the habit of crawling and pupating along the branches of the old mature larvae of the malignant leaf beetle, wrapping the trunk with mud straw and booby-trapping it. Be careful to treat it before the pupa feathers, so that the treatment is good.
(5) When adults resume activities and lay eggs on new shoots, as well as the occurrence of first-generation larvae and adults, it is the key to drug control, which can be used for high-efficiency cypermethrin, cypermethrin, high-chlorine methylvitamin salt, avermectin, etc.
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