What food do eighteen-star ladybugs usually eat?

Eighteen-star lady beetle is a kind of 28-star lady beetle, which is different from the seven-star lady beetle we are familiar with. It is good for crops if it feeds on aphids and leaf mites. Eighteen-star ladybug, also known as potato ladybug, sour ladybug, the whole body is covered with yellowish-brown fine hair, the body is relatively small. What kind of food does the eighteen-star ladybug usually eat? What's the difference between a 28-star ladybug and a ladybug?

What kind of food do ladybugs usually eat?

The eighteen-star lady beetle is a pest because its adults and larvae feed on the back of the leaves, leaving only the epidermis, forming a lot of irregular translucent fine grooves. The leaves can also be eaten into holes or only veins, when serious, the damaged leaves dry up, turn brown, and the whole plant dies. Eggplant fruit and melon strips are often cracked, and the tissue becomes stiff, rough, bitter and unedible.

What's the difference between an eighteen-star ladybug and a 28-star lady beetle?

(1) Potato ladybug (18-star ladybug)

The adult is 7-8mm long, hemispherical, reddish brown, with dense short hairs on the back and white reflection. There is a large sword-shaped pattern in the center of the forechest dorsal plate, with two small black spots on each side (sometimes merged into one). There are 14 black spots in each of the two sheath wings, and the four spots behind the three black spots at the base of the sheath wing are not in a straight line, and there are 1-2 pairs of black spots connected at the suture of the two sheath wings. The egg is spring-shaped, about 1.4mm long, bright yellow at first birth, then yellowish brown, and the arrangement of eggs in the egg mass is loose. When the larvae mature, the body length is 9mm, yellow, spindle-shaped, protuberant on the back, black spines on each segment of the back, and light black rings at the base of the spines. The pupa is long 6mm, oval, yellowish, with sparse fine hairs and black markings on the back, and the tail end is covered with the shell of the last molt of the larva.

(2) eggplant 28 star lady beetle

Similar to the potato lady beetle, but the adult is slightly smaller, there are six black spots in the forechest dorsal plate (sometimes four in the middle), the four black spots behind the three black spots at the base of the sheath wing are almost in a straight line, and the black spots at the joint of the two sheath wings are not connected. The egg length is 1.2mm, and the eggs in the egg mass are arranged densely. When the larvae mature, the body length is 7mm, and the dorsal branches of the larvae are white.

(3) performance of harm

Potato ladybug mainly harms potato, eggplant, pepper, tomato, legume and melon vegetables, among which potato and eggplant suffer the most. Eggplant 28 lady beetle mainly harms eggplant, tomato, potato, pepper, melon and other vegetables, among which eggplant suffers the most. The two kinds of lady beetles mainly harmed the adults and larvae. The newly hatched larvae ate the mesophyll on the back of the leaves, leaving only the epidermis, forming many parallel translucent fine grooves, and the larvae dispersed gradually after a little larger. Both adults and larvae can eat the leaves into perforations, and in severe cases, only thick veins are left. In addition, it can also harm tender stems, petals, sepals and fruits. Not only the yield of the damaged plants decreased, but also the fruit quality was poor, and the fruit became stiff, bitter and unedible.

(4) occurrence regularity

Potato ladybugs occur 1-2 generations a year in northern Liaoning. Adults survive the winter in leeward-facing caves, crevices, tree holes, bark seams and hillside rocks, soil caves, and weeds. The activity began in the middle and late May of the following year, first perched on weeds and small trees near the overwintering site, and after 5-6 days, the flying ability was restored, and then moved to potato, eggplant, tomato, pepper and wild eggplant weeds to feed. The peak of damage to the first generation of larvae was from late June to early July.

The peak of damage to the second generation of larvae was from the middle of August to the first ten days of September. Adults lie dormant in the morning and evening, feeding, flying, migrating, mating and spawning during the day, with the most active from 10:00 to 16:00 in the afternoon. Eggs are mostly laid on the back of the leaves, generally there are 20-30 eggs in each egg block, standing on the back of the leaves, each female can lay nearly 400 eggs. The egg stage varies with temperature, ranging from 5 to 11 days. After hatching, the first instar larvae were clustered to feed on the back of the leaf, and gradually dispersed after the second instar. The larva was 4th instar, the larval stage was 16-26 days, and pupated on the back of the leaf, on the stem or at the base of the plant after maturity, and the pupal stage was 4-9 days.

The first generation of adults appeared from late June to early July, and the adults in this stage could lay eggs on the back of the leaves of each host. Therefore, the population of insects in this period increased significantly, and the damage was also obviously serious. by the first ten days of September, most of the adults of the second generation had emerged. After a period of damage, they began to look for various gaps and lurk through the winter in the middle and late September. Adults have pseudo-death and egg-eating habits, and larvae also have egg-eating habits. The occurrence rule of eggplant 28 lady beetle is similar to that of potato lady beetle, but the overwintering clustering phenomenon is not obvious. the adults feed day and night and have the habit of killing each other on eggs and pupae. There are generally 15-40 eggs per egg block. Adults and larvae are afraid of light and often move on the back of leaves and other hidden places.

The optimum temperature for adult potato ladybug is 22-28 ℃. When the temperature is below 15 ℃, it can not lay eggs, and when it is higher than 35 ℃, it dies one after another. At high temperature in summer, adults live quietly and occur more seriously in the fields where the branches and leaves are luxuriant and more shady. The suitable temperature for the growth of adult ladybug 28 is 25-28 ℃, and the relative humidity is 80% 85%. When the temperature drops to 18 ℃, it enters the overwintering state. Potato ladybugs must feed on potatoes in whole or in part, otherwise they can not develop and lay eggs normally, so they can occur in large numbers only in potato producing areas.