wheat bulb fly

The Wheat Bulb Flu (Delia coarctata) is a small fly - the larvae (grubs) burrow in stems and cause tillers to die (dead-heart damage symptoms).


Wheat bulb fly, Delia coarctata, is found more in the eastern half of England than in other parts of the UK. It lays eggs on bare soil which means it can be more of a problem after fallows or crops that are harvested early. It is worse on light soil. It lays eggs in July to September and particularly likes freshly cultivated soil and will lay eggs between rows of crops where there is bare soil. Eggs are dormant until January-March when they start to hatch. The larvae (grubs) then start to move through the soil to invade cereal plants. They bore into the base of cereal plants and feed on the central shoot. All cereals except oats are attacked but the fly is most serious in wheat. Larvae burrow in the middle of stems causing tillers to die and exhibit ‘deadheart’ symptoms (view Gallery). Any crops which only have a single tiller (winter wheat drilled late or spring crops drilled before March) at the time when the pest attacks are particularly at risk because they are not able to compensate for damage.

Levels of the pest vary from year to year according to harvest times and rainfall. Wheat bulb fly levels are generally highest after a wet harvest period the previous year.

Management Options

Egg populations above 250/ m² represent a risk of economic damage to autumn drilled crops. The 2015 AHDB sponsored ADAS survey of egg levels has found that risk is higher than any other year since 2011 and that average egg numbers in the north were higher than in the east. The mean egg number was 168 eggs/m² for sites sampled in northern England, which represents moderate risk, but some sites are at high risk (3 out of 15 sites). This may mean that egg hatch sprays are required. Seed treatments reduce risk but egg hatch sprays may still be needed for late drilled crops in places where levels of the pest are high. If plants are well-tillered by the time the wheat bulb fly larvae hatch, it is possible that they will be able to tolerate some pest attack and an insecticide spray may not be required.

Cultural control methods to reduce risk include drilling early, avoiding deep drilling, increasing the seed rate to allow compensation for attack and early top dressing to aid crop recovery.

Related links

Information and image from Rothamsted's Croprotect webpage supported by BBSRC NERC Sustainable Agriculture Research & Innovation Club

Related Organisations

Content below is from across the PEP community and is not necessarily endorsed by Stewards or by PEP

Connected Content

Integrated Pest Management highlights the growth of a healthy crop with the least possible disruption to agro-ecosystems and encourages natural pest control mechanisms. IPM is one of the tools for low-pesticide-input pest management, and IPM must now be implemented by all professional agchem users.

Orange wheat blossom midge can seriously damage yield and quality of susceptible wheat varieties but it depends on whether the egg-laying adult females emerge at the time when the wheat is at the at risk growth stage. Adults are small (1.5-2.5 mm long) and are a very distinctive bright orange colour.

Invertebrate pests cause problems in agriculture when the level of injury they cause reaches a point where the crop yield is significantly reduced.   

Wheat is the most widly grown crop in the UK. Nationally yields average around 8 t/ha/

Black Soldier Fly (BSF) larvae are an alternative source of protein for animal feed, having an insatiable appetite consuming large amounts of organic material from both plants and animals. This ability, coupled with BSF feed conversion efficiency that compare favourably to fish meal and soybean meal, has led to an increased global interest in the development and adoption of BSF farming and BSF bioconversion technology. 

Write whatever you want here - this is the main section. You can add links, add pictures and embed videos. To paste text from elsewhere use CTRL+Shift+V to paste without formatting. Add videos by selecting 'Full HTML' below, copying the 'embed html' from the source page (eg Youtube), clicking 'Source' above and pasting where you want the video to appear.
You can upload an image here. It can be jpg, jpeg, gif or png format.
Upload requirements

You can upload a file here, such as a pdf report, or MS Office documents, Excel spreadsheet or Powerpoint Slides.

Upload requirements
Authors Order
Add Authors here - you can only add them if they already exist on PEP. Just start writing their name then select to add it. To add multiple authors click the 'Add another item' button below.

Please ensure that you have proof-read your content. Pages are not edited further once submitted and will go live immediately.