English Grain Aphid

The English grain aphid (Sitobion avenae) is a pest that infests wheat, barley, oat, rye, timothy, and canaryseed. Adults are 1.5 to 2 mm in size and yellow-green to reddish-brown with black antennae, leg joints, and cornicles. Nymphs are similar in appearance, but smaller in size. 

Adults and nymphs of the English grain aphid. Picture credit: Jennifer Otani, AAFC-Beaverlodge.

Aphids are typically found on the heads of cereal crops, where they feed on the ripening kernels. Feeding damage results in shriveled kernels and leaf discoloration. Severe infestations result in large visible bronze or brown patches in the field. English grain aphids produce honeydew, a sugary liquid waste, that can promote the infestation and growth of saprophytic and pathogenic fungi on cereal heads. This aphid is also a vector for barley dwarf virus, which can severely stunt plants and prevent heading. 

English grain aphids on a cereal head. Picture credit: Jennifer Otani, AAFC-Beaverlodge.

The economic threshold for English grain aphids in spring wheat in western Canada is 12-15 aphids per head prior to the soft dough stage. The number of aphids per head should be recorded on 20 tillers at five different spots scattered throughout the field to ensure an accurate estimate of their population density. Scouting should occur from June until the soft-dough stage is reached. Early seeding may allow crops to move past susceptible stages before aphid populations reach damaging thresholds and reduce risk for barley yellow dwarf virus.  

More information related to English grain aphid and other aphid species can be found on provincial the Manitoba Agriculture page. For more information, check out the English grain aphid page in the Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and Management field guide. (en français : Guide d’identification des ravageurs des grandes cultures et des cultures fourragères et de leurs ennemis naturels et mesures de lutte applicables à l’Ouest canadien).  

Extra Insect of the Week – English grain aphid (Hemiptera: Aphididae)

The English grain aphid (Sitobion avenae) has started to appear across the Prairies in various cereal crops this past week so the time to scout is now. Look for this aphid infesting wheat heads (favourite host) as well as barley, oat, rye, Timothy and canaryseed.

This aphid can also be a vector for barley yellow dwarf virus. You might see the green, red colour morph or both morphs in fields this year (Fig. 1). You will probably also see ladybeetle (@FieldHeroes) adults and larvae hunting the aphids (Fig. 2). The economic threshold for aphids in spring wheat in Western Canada is 12-15 aphids per head prior to the soft dough stage. 

Agriculture and Agri-Food Canada, with funding from the Pest Management Centre, has developed a smartphone app called Cereal Aphid Manager (CAM) to facilitate scouting for aphids in cereals that also allows you to record the beneficial insects in the field that can keep aphid populations below the economic threshold – available at Apple iTunes and Google Play app stores. CAM information and download links.

For more information on the English grain aphid, check out our Insect of the Week page!

Submitted by Dr. Tyler Wist (Tyler.Wist@agr.gc.ca).

Fig. 1 Green and red morph English grain aphid
(Tyler Wist, AAFC)
Fig. 2 Seven-spotted lady bird larva hunting aphids
(Tyler Wist, AAFC)

Insect of the Week – Aphidius parasitoid wasp

This week’s Insect of the Week is the Aphidius parasitoid wasp. Their hosts include over 40 species of aphids. Egg to adult development occurs inside the host. New adults chew a hole in the mummified aphid to exit and immediately search for new aphid hosts.

For more information on the Aphidius parasitoid wasp, see our Insect of the Week page.

Parasitized English grain aphid (Tyler Wist, AAFC)
Aphidiidae – adult (Aphidius avenaphis) (Tyler Wist, AAFC)

Follow @FieldHeroes to learn more about the natural enemies that are working for you for FREE to protect your crops!

Remember the NEW Cutworm Field Guide is free and downloadable in 2017!

Insect of the Week – Aphidius avenaphis


Last year, the focus of the Beneficial Insect of the Week
 was crop pests. This year, we’re changing things up and highlighting the many natural enemies that help you out, silently and efficiently killing off crop pests. [note: featured Insects of the Week in 2015 are available on the Insect of the Week page] 

This week’s Insect of the Week are Aphidiidae wasps*. While you won’t likely see them flying about attacking aphids, this tiny wasp can parasitoidize 100-350 aphids during its relatively short lifetime.  The resulting aphid ‘mummy’ ceases causing crop damage and instead becomes a living host for the developing wasp. After 2 to 4 weeks of development, a new adult Aphidiidae wasp emerges and starts hunting for aphids to continue the cycle. To see an Aphidius avenaphis wasp in action, see: https://www.youtube.com/watch?v=T7PNlpEgvEM&feature=youtu.be

For more information about this natural enemy, other pests they control and other important crop and forage insects, see the new Field Crop and Forage Pests and their Natural Enemies in Western Canada – Identification and Management Field Guide for identification, life cycle and conservation options (download links for field guide available on the Insect of the Week page).

* this wasp genus only attacks aphids, not humans.

Adult Aphidius avenaphis© AAFC, Tyler Wist

English grain aphid mummy, cc-by-sa 2.0 Gilles San Martin