[Smart Farmers] Pay attention to this living "little stick"! How powerful is the "master of disguise" in the biological world?

In nature, many animals are masters of mimicry. Some of them do this to avoid predators, while others do it to better hunt. They are a very common but often overlooked moth: disguised to look like a stick. Even if it is right next to you, you may not even notice it. It is the "round-palmed boat moth".

What is the round-palmed moth?

Phalera bucephala Linnaeus is a species of insect in the family Phalera. It is mainly distributed in Northeast my country, Inner Mongolia, Xinjiang and other places; abroad, it is mainly distributed in North Korea, Russia (Siberia), Europe, Northeast Africa and East Asia.

There are four stages of the round palm moth: egg, larva, pupa, and adult. The egg is bun-shaped, about 1 mm long, light green when first laid, mostly white on the upper part, with only a green dot in the center, and turns brown when it is about to hatch. The larva is yellow except for the head, with light gray hair. The center of the head along the midcranial groove and the frontal area are yellow, forming a clear inverted "V". The body has 10 intermittent black longitudinal lines. The pupa is about 24-29 mm long, dark brown, and the end of the pupa is blunt. The adult body is 22-24 mm long, with a wingspan of 50-64 mm, and the female is larger. The forehead is brownish yellow, and the top of the head and the neck plate are light yellowish brown. The forewings are mainly gray-brown and slightly shiny. The hind wings gradually turn into milky white, with a slightly darker front edge and a light white-yellow patch at the end.

egg

larva

pupa

Adult

(Picture from the Internet)

How does the round-palmed moth camouflage itself?

Unlike other lepidoptera that mimic tree branches, the adult of the round-palmed boat moth, rather than the larvae, mimics the tree branches. When the adult is stationary, it quickly wraps its wings around its body, turning it into a barrel shape. The gray wings and the lines on the wings make the surface of the round-palmed boat moth's body look very much like dry bark, while the brown-yellow part of its head looks like the cross section of a tree branch. If you don't look closely, it's hard to tell whether it's a real branch or an insect.

What is the damage caused by the round-palmed boat moth?

The host plants of the round-palmed moth include willow, poplar, elm, birch, hazel, walnut, beech, lime, apple, pear and cherry, etc. Its main damage method is that the larvae feed on the host leaves. The first-instar larvae feed on the upper epidermis and mesophyll, and the leaves turn black and slightly transparent after being damaged. The older larvae eat the leaves voraciously, often eating the leaves on some branches to make them bare, seriously affecting the growth and development of the trees.

How to prevent and control the round-palmed moth?

There are three common prevention methods. First, physical control can be achieved by using the phototaxis of adult insects to set up lights to lure and kill them. At the same time, when the older larvae are in a state of suspended animation, artificial tree shaking can be performed in the morning and evening to catch and kill the older larvae. Second, chemical control should focus on larvae before the third instar. Various pyrethroid pesticides have obvious control effects. Finally, biological control can effectively kill larvae by spraying biological insecticides such as Beauveria bassiana and Bacillus thuringiensis. Natural enemies such as parasitic wasps can also be introduced for control.

Author: Zhang Yuxin (graduate student at the School of Life Sciences, Hubei University)

Scientific review: Xu Letian (Associate Professor and Doctoral Supervisor at Hubei University)

Planning: Zhao Qingjian, Wu Yuetong

Proofreader: Han Chengguo (internship)