Frit fly

frit fly

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frit fly — n. [< ? FRIT, from the glazed, shining appearance of the fly s body] any of a family (Chloropidae) of tiny dipterous flies whose larvae destroy grain, esp. a black species (Oscinella frit) … English World dictionary

frit fly — “ noun Etymology: origin unknown : a fly of the family Chloropidae (especially Oscinella frit) injurious to grain in Europe * * * a minute European fly, Oscinella frit, the larvae of which are serious pests of wheat and other cereals. [1880 85;… … Useful english dictionary

frit fly — noun a very small black fly whose larvae are a serious pest of cereal crops and maize. [Oscinella frit.] Origin C19: from L. frit particle on an ear of corn … English new terms dictionary

frit-fly — n. (pl. flies) a small fly, Oscinella frit, of which the larvae are destructive to cereals. Etymology: 19th c.: orig. unkn … Useful english dictionary

swedish fly — noun Usage: usually capitalized S : frit fly … Useful english dictionary

Oscinis frit — Oscinian Os*cin i*an, n. (Zo[ o]l.) Any one of numerous species of dipterous flies of the family . [1913 Webster] Note: Some, whose larv[ae] live in the stalks, are very destructive to barley, wheat, and rye; others, as the barley… … The Collaborative International Dictionary of English

fritfly — frit fly n. Any of several small flies of the family Chloropidae, especially Oscinella frit, having larvae that are destructive to cereal plants such as oats and wheat. [Origin unknown.] * * * … Universalium

dipteran — /dip teuhr euhn/, adj. 1. dipterous (def. 1). n. 2. a dipterous insect. [1835 45; DIPTER(A) + AN] * * * Any member of the more than 85,000 species in the insect order Diptera (the two winged, or true, flies), characterized by the use of only one… … Universalium

Fritfliege — Frịt|flie|ge 〈f. 19〉 bis zu 3 mm lange, glänzend schwarze Halmfliege, deren Larven die Herztriebe des Getreides im Grunde zerstören: Oscinella frit [<engl. frit fly „Frit , Haferfliege“] * * * Frịtfliege, Oscinẹlla frịt, 2 mm lange… … Universal-Lexikon

Agriculture in the United Kingdom — A combine harvester in Scotland Agriculture in the United Kingdom uses around 71% of the country s land area and contributes about 0.6% of its gross value added. The UK produces less than 60% of the food it eats and the industry s share of the… … Wikipedia

Estimating Crop Yields and Crop Losses

Note Number: AG0104
Published: January 1998
Updated: May 2012

Accurate, early estimations of grain yield and crop loss are important skills in grain production. Farmers require accurate estimates for:

  • crop insurance purposes
  • forward marketing and delivery planning
  • planning harvest and storage requirements
  • cash-flow budgeting.

Extensive personal experience is essential for estimating yields at early stages of growth. As crops near maturity, it becomes easier to estimate yields with greater accuracy.

Estimation methods

A simple but accurate formula for estimating cereal grain yield is based on the number of heads per 500 mm of drill row, the number of grains per head and the size of the grain.

Formula for estimating grain yield

Average number X Average number of heads
of grains per head per 500 mm of row = tonnes/hectare
Known constant (K)

The «known constant» is that number of grains in the half metre of row at 175 mm row spacing that is equivalent to 1 tonne per hectare.

It is more difficult to count the number of grains per 500 mm of row for trailing crops such as field peas and lentils, but if managed, the average number of grains per 500 mm of row divided by the appropriate known constant will provide a yield estimate. Alternatively, you can use the formula for estimating losses, by counting the number of grains of these crops per 0.1 sq m and divide by the known constant «X» from table 3. This will also give a yield estimate.

The value of the «known constant» varies according to the grain weight, which differs for each type of crop. Even within the same crop it may be necessary to adjust the «known constant» to compensate for a heavier or lighter grain weight. For example, in seasons of heavy rust infection the «known constant» for wheat is generally decreased to compensate for lighter grain weights.

A range of «known constants» for different grain weights is shown in Table 1.
Estimation accuracy, regardless of method, depends on the accuracy of observations taken in the field. Counts of grains per head and heads per length of row must be accurate and taken randomly at enough locations (at least 10) to provide an average count representative of the whole field.A length of steel rod or light timber, cut or clearly marked in half-metre segments, is a useful measuring aid. Another useful aid is a pre-ruled form for recording of counts. This is used for calculation and a permanent record of the yield estimate.

Table 1. «Known constants» for various grain weights

Known constant (K)
(grains/500 mm of row)

Controlling Insects in Stored Grain

ENTFACT-145: Controlling Insects in Stored Grain | Download PDF

by D.W. Johnson and L.H. Townsend, Extension Entomologists
University of Kentucky College of Agriculture

Over 50% of the grain produced in Kentucky is held in «on-farm» storage for some period of time. In the past this storage was short-term, from harvest until early spring. However, times have changed drastically. Now, storage periods of 12 months or longer are common. As a result, grain remains undisturbed for long intervals, including the high risk, warm, moist months from late spring to early fall.

The primary causes of grain spoilage in Kentucky are excess moisture and high temperature. However, any grain improperly handled or stored longer than 6 months can be infested by insects. The key to successful storage is to anticipate and prevent potential problems through good bin management practices. Preventing insect problems in stored grain requires 3 steps: 1) sanitation, 2) protection and 3) inspection.


Stored grain insect infestations rarely begin in the field. Most develop from small numbers of pests already present in or around farm storage bins. An effective sanitation program can eliminate or greatly reduce the chance of having serious problems with these insects.

Equipment: Grain handling equipment should be kept clean. The effort involved in thorough preparation of storage bins is of little value if they are filled using contaminated equipment. Combines, trucks, augers and grain driers should be thoroughly cleaned of all old grain.

The Empty Bin: Never put newly harvested grain into bins containing old grain. Empty the bins of all residual grain, then use shovels, brooms and industrial vacuums to complete the job. Be especially careful to clear dust, webbing and fines from around any cracks and crevices, doors, seams, vents and especially under false floors. Even small amounts of old grain left in the bins may harbor enough insects to start a problem. Once the bins are clean, inspect them and repair any cracks or holes which would allow moisture or insects to enter. Then, spray the inside completely with an insecticide. (See Insecticides and Fumigants)

Near the Bin: The area immediately surrounding the bins should be kept clean. Be sure to remove and destroy all spilled grain. Control weeds and grasses, since they can harbor insect and rodent pests. Inspect outside walls and especially the base and roof for damage that could allow pests and moisture to enter. Do not use the area immediately surrounding the grain bins to store cattle feed; keep stock feeders as far away as possible.

The Grain: Store only clean, dry grain. A small percentage difference in moisture content can make a big difference in the probability of a damaging insect infestation. The optimum moisture content for stored grain is 12-13%. Most grain inhabiting insects require 13-15% moisture for maximum feeding and reproduction.

It is also advisable to clean grain before binning. Small pieces of dockage and cracked or split grain provide food for insects not normally found in whole grain. Even though most of these insects will not feed on whole grain, their biological processes produce heat and moisture which can greatly reduce the stored grain’s quality.

Level the grain surface once the bin has been filled. This will allow for good air flow and thus improved moisture and temperature control. It also will allow improved access for inspection and treatment.


In empty bins, apply a coarse spray of an approved insecticide to run-off at least 2 weeks before binning (See Insecticides and Fumigants). Pay close attention to areas which might hide insects, such as under false floors and vents. Cracks around doors and vents may serve as sources of infestation.

A grain «protectant» is an insecticide that can be applied to the bulk grain as it goes into a storage bin (See Insecticides and Fumigants). The treatment offers protection for about one season and should be considered if the grain may be held for more than 6 months. Proper calibration of the application system is important to ensure even insecticide distribution throughout the grain. Protectants are effective against both beetle and caterpillar pests.

A surface dressing (Cap Out) may be applied to prevent insects from entering the top of the grain mass and to control surface infestations of Indian meal moth, when a «protectant» is not used (See Insecticides and Fumigants). Though surface dressing may be useful if a grain protectant is not used, it will not reduce an established infestation within the grain mass. Producers anticipating problems with these pests should follow some specific steps:

Apply the surface dressing as a coarse spray in enough water to obtain adequate coverage. The recommended amount of water differs among products, so check the label of the insecticide you choose. After you spray, incorporate the insecticide into the top 4 inches of grain surface.

To compute how much insecticide you need for top dressing, select the desired product (See Insecticides and Fumigants) and multiply the recommended use rate (example, 1 pt/1000 bu) by the proportion of 1000 bushels contained in the top 4 inches of your bin. Table 1 lists the proportion of 1000 bu in the top 4 inches of some common sized bins. For example, if you wish to top dress a 24 ft bin with a compound at the rate of 1 pt/1000, then 1 pt. x 0.119 = .119 pt or 1.9 oz.

Infestation in the Grain Bulk

Fumigants are gases that penetrate the grain and kill insects both on and in the grain. They are very toxic to man and animals and should be applied only by trained, experienced operators working in pairs.

Once an insect infestation has become established, there are only two treatment options: (1) move the grain and apply a protectant during transfer or (2) fumigation. Both choices have good and bad points. Application of grain protectants during movement will provide some residual protection. But moving grain is costly, time consuming and requires additional bin space. Also, if good control is not achieved, movement will spread the insects throughout the grain mass. On the other hand, fumigation works very well and is relatively cheap. Fumigants are gases that penetrate the grain and kill insects both on and in the grain. They are very toxic to man and animals and should be applied only by trained, experienced operators working in pairs. But because it is very sensitive to poor technique, many failures occur. Also, it is dangerous and provides no residual protection.


Several factors are important in assuring successful fumigation.

  • Grain should always be level in the bin to let the fumigant penetrate evenly.
  • Any surface caking or crusting should be broken up and removed.
  • Grain temperature should be 60°F or higher to ensure proper vaporization.
  • Possible leak points such as cracks or holes in the bin should be closed before fumigation since leakage may result in under treatment and poor control.

Causes of Fumigation Failures

Fumigation failures can usually be attributed to one or more of the following:

  • Insufficient fumigant—A fumigant’s efficiency depends on its attaining a lethal concentration in the grain. Results will not be satisfactory if less than the recommended dosage is used or if the fumigant is applied under unfavorable conditions.
  • Storage structure—Leaky bins will not retain fumigants long enough to kill the insects. The depth of grain also affects a fumigation’s efficiency. In general, the greater the surface area of the grain in relation to bulk, the greater the difficulties in adequate fumigation. As a result, flat storage bins require higher dosages than do round silo bins. Also, storage structures with a large amount of space over the grain are difficult to fumigate effectively because large amounts of gas escape into that space.
  • Moisture—As moisture content increases above 12% a proportionately higher dosage of fumigant is required. It is difficult to effectively fumigate grain having a surface moisture content of 15 to 20% because the fumigant vapors will not penetrate the moist layer.
  • Temperature—During fumigation, the gas quickly assumes the temperature of the grain. In general, fumigant activity increases as temperature increases. However, if grain temperature reaches or exceeds 115 °F, the fumigant may vaporize very rapidly and escape from the bin before accomplishing the job. On the lower end of the spectrum, stored grain insects are inactive at temperatures below 60°F. Fumigation should be delayed until the grain temperature increases.


Should fumigation become necessary, a variety of compounds are available for treatment (See Insecticides and Fumigants). Fumigants are inherently dangerous and should be applied only by trained operators. Operators should wear a full face gas mask equipped with the proper canister, and have access to self contained breathing apparatus, and another person should always be present during fumigation.

Refer to the training material developed by the manufacturer.


Grain bin inspection provides important information on the general condition, temperature, moisture and pest activity of stored grain. Inspections allow early detection of problems and enable corrective action to be taken before damage becomes severe See: «Aeration, Inspection and Sampling of Grain in Storage Bins,» Extension publication AEN-45, provides procedures for checking storage facilities.

Using Probe Traps for Insect

The commercially available «probe» traps may be the easiest and safest way to monitor for several beetles that can infest bins. These traps are hollow «plastic» tubes with a series of downward sloping holes all along the sides. The top is a flat cap. The bottom is a pointed piece that screws in place. Insects crawling into the tube through the small holes can accumulate at the pointed end of the trap. A nylon line should be securely attached for easy retrieval from the grain mass.

These traps can be inserted in the grain using a long pole with a cup device on the end. This device is easily made using a paint roller extension handle and some «PVC»plumbing fixtures. Attach to the extension handle, a PVC «reducer» that has one side just about the size of the screw on the end of the extension handle while the other side is large enough to serve as a cup over the end of the trap. This will allow you to push the trap into the grain from an inspection hatch, internal ladder, or some other safe place, thus avoiding having to cross the grain surface.

The trap is retrieved using a nylon line which was attached to the trap before it was placed in the grain, and tied off to some convenient location in the bin. The line will also serve to keep traps from being sucked into the grain stream in case they are forgotten at unloading time.

How many traps are needed? The greater the number of trap samples, the greater the probability of detecting insect activity. For grain, the standard is 4 to 5, certainly now fewer than three, per round bin.

Thresholds for a one-week sampling period vary with species sampled and the grain Temperature (Table 2). If grain temperature is below 60o F, the numbers in Table 2. indicate a very high population size.

Economics of Pest Control

The constant fluctuation of grain prices and costs of insecticides, as well as attitudes of local buyers, make it impossible to set a specific cost-return value for treatment of stored grain. In Kentucky, most often the cost of an insect infestation in stored grain is that the buyer pays less for that grain. Find out what local buyers dock for infested grain, and compute the cost of treatment to see which provides the best return. If grain is plentiful, buyers can be choosy so the dock for infested grain will be greater. In that case, treating infested grain is usually more cost effective. On the other hand, if grain is scarce, buyers may not dock at all for insects, so treatment would be cost prohibitive. It is never cost effective to treat non-infested grain.

Insecticides and Fumigants

Labeling and application regulations for fumigants and grain protectants are subject to change. To insure that information on these products is as current as possible lists of insecticides and fumigants for use in stored grain may be found in the appropriate annually revised commodity publications as follows:

ENT-13 Insecticide Recommendations for Soybean
ENT-16 Insecticide Recommendations for Field Corn
ENT-24 Insecticide Recommendations for Grain Sorghum (Milo)
ENT-47 Insecticide Recommendations for Small Grains (Barley, Oats, Wheat)

Do not use malathion as residual treatment for empty bins, a protectant or ‘capout’ treatment. Malathion labeling is being removed for stored grain. More importantly, several stored grain pests have exhibited tolerance to malathion.

Common Stored Grain Insects In Kentucky

A variety of insects can be found in Kentucky stored grain. Fortunately, only a few are responsible for most problems and most of them are relatively easy to identify. These pests are divided into two main groups the beetles and the caterpillars. The caterpillars are easily identified. However, stored grain beetle pests are quite small so a hand lens is needed to see enough features to determine if important pests are present.

Indian meal moth (right) is one of the most common and troublesome insects attacking most any type of stored grain. The adult is a moth with a coppery color on the outer two-thirds of the front wings. Presence of the adult, though not damaging, can indicate the presence of an infestation. The moths lay eggs on the gain surface. These eggs hatch into the caterpillars (worms) that cause damage. The worm is about ½» long when grown and whitish in color. IMM rarely causes extensive kernel damage, or grain discount at the time of sale. However, the larvae may completely web over the grain surface, thus preventing proper air movement for aeration and fumigation and causing surface grain moisture accumulation and «top crusting».

The most common beetles, often called «bran bugs» (pictured left), do not feed on whole sound kernels, but rather live on broken kernels, dust, and trash. There are two major types in Kentucky the «flour beetles» and the Cryptolestes beetles. These insects are likely to be found in every bin of stored grain in the state. The real question is are there enough to do and damage?

There are two flour beetles (pictured right), Red flour beetle and the Confused flour beetle. They look very much alike and are separated by examination of the last three segments on the antennae. However, these beetles are usually found together in an infestation and do about the same damage.

There are also two common Cryptolestes beetles. They are the flat grain beetle and the rusty grain beetle. They look very much alike and are about one-half the size of the flour beetles. They are very flat in appearance and have beaded antennae about one-half as long as the body. They are often found in mixed infestations with flour beetles and do a similar type damage, but it takes two to three times as many flat/rusty grain beetles to do the same amount of damage as the flour beetles.

Perhaps the two most dangerous insects in Kentucky stored grain are the «weevils», which are usually found in corn, and the lesser grain borer which is more often a problem in wheat.

The weevils (pictured left) are relatively easy to tell apart from other insects because of their «snout». These are long, thin, downward curving mouth parts sticking out from the head.

The lesser grain borer also has a distinctive shape. However, it is the overall look of this insect that allows the identification. Lesser grain borer are very cylindrical in shape and both the head and tail end look very flat. It is kind of like using a straw to take a plug out of an apple only much smaller.

Both the weevils and lesser grain borer are primary feeders. They both feed on whole, sound kernels and their young develop inside the kernel. Infestations of these insects are very important.

Most other insect pests are secondary feeders. They cannot feed on whole sound kernels, but rather do their damage by their presence, and the heat and moisture they generate.

There are a large number of other insects that can infest stored grain. You may find information, pictures of these insects and links to other storage sites at: IPM in Kentucky Farm Stored Grain


Issued: 6/03
Revised: 7/09

CAUTION! Pesticide recommendations in this publication are registered for use in Kentucky, USA ONLY! The use of some products may not be legal in your state or country. Please check with your local county agent or regulatory official before using any pesticide mentioned in this publication.


Swedish fly — a dangerous pest of cereals

The Swedish fly is a representative of cereal flies. This fly is one of the main ills of agriculture. These pests are highly adaptable to various climate fluctuations, which is why they spread throughout the world and are found even in the Arctic. Swedish flies can survive a week even without food.

Types of Swedish Flies

There are different types of Swedish flies that differ in diet. The most famous species are oatmeal and barley fly. Oatmeal flies feed on young stalks and young oats, while barley flies favor cereal grasses such as wheat, barley, and, less commonly, corn.

The appearance of the Swedish fly

The larvae of Swedish flies reach a length of 4.5 millimeters. The body of the larvae is cylindrical, oblong, consisting of 13 segments. There are no paws, but instead of them there are small spines, with the help of which movement is carried out.

The head does not clearly differ from the body, it can be recognized only by the upper spiracles, small antennae and sickle-shaped mouth apparatus. Initially, the color of the larva of the Swedish fly is milky, and the body is transparent, but as it grows, the color becomes bright lemon.

Swedish fly (Oscinella).

Adults are 2 times smaller than larvae — the size of the Swedish fly in rare cases is more than 2 millimeters.

The head of the Swedish fly is round, neat, with a small proboscis on it. The back is smooth. The color of the Swedish fly attracts attention: the body is black, shiny, the abdomen and legs are white-lemon, and the wings are greenish with a metallic tint.

Swedish fly is a tiny pest of cereal plants.

Breeding swedish flies

In one season, the generation of Swedish flies is updated up to 5 times. Before laying eggs, a female Swedish fly chooses a future home for her offspring. Swedish flies lay eggs in plants of only a certain developmental phase. In this regard, the female checks all the stems, stroking them with her antennae. Most often, they choose young shoots with a pair of developed leaves. In the axils of the leaves, the fly lays eggs.

The size of the eggs is about 7 millimeters. The larvae inside the egg develop about 8 days. When the larvae emerge, they gnaw through the stem and crawl into it. Larvae feed on the germ of future grains until they begin to harden. In the stings of the larvae there are special salivary glands that secrete a special enzyme for splitting plant tissues.

The larvae of the Swedish flies feed on the stalks of cereals, causing damage to the crop.

Swedish flies diet

Adults feed on nectar of colza, buckwheat, lupine, anise and other wild plants. The Swedish fly has an excellent sense of smell, so it is not at all difficult for her to find a flowering field. In addition, Swedish flies love to feast on molasses. And as a protein food, they eat the smallest aphids.

Thanks to a good sense of smell, the Swedish fly finds a field with flowering cereals and feeds there.

The harm of Swedish flies

The biggest damage to crops is caused by the larvae of Swedish flies, which eat away cereals and nearby tissues. As a result, central leaves die off in cereals, which leads to a slowdown in plant growth or to its complete death.

The shoots damaged by the Swedish fly have dark greens, and the stems are thickened. Larvae eat grain, preventing them from ripening, which leads to a decrease in yield.

Swedish flies themselves are not so harmful as their larvae.

The total amount of damage caused by the Swedish fly consists of various factors: tillering delays (plants that have several lateral stems tolerate infection), pest choice of lateral or central stems, air temperature (at -10 Swedish flies hibernate) , the nutritional conditions of the shoots (the more food enters the plant, the stronger it is, which means it has a higher chance of survival).

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Weight of 100 grains