Pest Type: Cereal Pest
Row: Hymenoptera – Hymenoptera
Family: stem sawflies – Cephidae
It is ubiquitous in Russia, but its largest number is in the steppe zone. It damages wheat, rye, barley, oats, seeded and wild-growing grasses, but mostly winter wheat and rye.
The image is 6-10 mm long, the main color is black, with shine. On the abdomen, there is a clear yellow pattern in the form of rings on the fourth, sixth, ninth, often seventh, and also (in the male) third segment. Wings almost transparent, grayish with brown venation. The antennae are long. The eggs are white, elongated oval, somewhat curved, about 1 mm long.
The larva is yellow-white or yellowish, when viewed from the side, curved. It has underdeveloped legs and a soft process at the end of the abdomen, bearing 6 to 9 spines. The chairman is brownish yellow. The length of the larva of the last age before wintering in the cocoon is 12-14 mm.
Pupa open, yellowish or grayish-white.
Larvae of the last age, winter eonymphs, in oblong transparent cocoons inside the “stumps” of stubble of wheat, barley, rye overwinter.
After sustained warming, pupae form in spring. After 8 – 20 days, the sawflies begin to fly, which usually coincides with the completion of the exit phase into the tube – the start of winter wheat earing. Years continue until the end of the grain formation phase, and in years with hot, dry weather ends earlier.
For 3 – 5 days, sawflies feed on nectar on the flowers of many plants, especially cabbage and milkweed. In search of feed, they often gather on the margins of fields, in forest belts adjacent to flowering vegetation, in particular on legumes. After feeding, they populate crops of ears of corn, mainly wheat, where they lay eggs. Using a sawtooth ovipositor, the female makes an incision on the stem between the leg of the ear and the upper node and deepens the egg inside the straw. She lays an average of 30 to 50 eggs, choosing more developed stems with a thick straw. Embryonic development lasts 5 to 10 days. Immediately after rebirth, the larvae feed on the inner part of the stem and move down to its base. At the nodes of the stem they gnaw holes, large segments of the course in the straw are clogged with excrement. The bulk of the larvae reaches the lower internode at the end of the loading phase – waxy ripeness of grain. At approximately the level of the soil surface, the larva inside the stem makes an annular incision, under which it forms a protective chop with scraps and excrement. Then a transparent cocoon is spun in the form of a protective shell in which it hibernates. Under the influence of wind, part of the stems breaks off at the incision site even before the onset of the phase of complete ripeness of the ears of corn.
The productivity of damaged stems, depending on varietal characteristics, agroclimatic conditions and the state of the sawfly population, is reduced by 1.5 – 10%.
Protective measures. Optimum sowing dates, timely harvesting, stubble disking in 1 – 2 tracks, autumn plowing.