Painted Lady Butterfly

This week, Alberta Agriculture & Forestry’s Scott Meers noted painted lady butterfly larvae (Vanessa cardui).  The larvae are important to scout for because this species feeds on a wide range of host plants including soybean (Action threshold=>25% defoliation), sunflowers, borage and dry beans in addition to several species of thistles (including Canada thistle) and mallow. 

The “Field Crop and Forage Pests and their Natural Enemies in Western Canada: Identification and management field guide” includes photos of both the larvae and adult.  The guide is available as an English-enhanced or French-enhanced version.  The Butterflies and Moths of North America website tracks confirmed sightings of V. cardui (screenshot provided below; retrieved 30May2019).

Invasive species: Brown marmorated stink bug

This week’s Insect of the Week is the brown marmorated stink bug (Halyomorpha halys). Stink bugs get their name from the foul odour they release when threatened. Brown marmorated stink bug is not known to be established in the Prairies, but the species has been found in the Southern Interior of BC, in Ontario and Quebec. Feeding causes damage to seeds and seed pods, reducing yield. Nymphs and adults prefer field corn and soybean, but infestations have been reported on rape, pea, sunflower and cereals in the USA. They have also been known to attack tree fruits, berries, vegetables and many ornamental trees and shrubs.

Brown marmorated stink bug – adult (CC-BY 2.0 Katja Schulz)

Additional information and fact sheets for this insect have been posted by Ontario Ministry of Agriculture, Food, and Rural Development, and BC Ministry of Agriculture and Seafood. You can also check out our Insect of the Week page.

This insect is featured in our Field Crop and Forage Pests and their Natural Enemies Field Guide which is available for download from the Insect Field Guide page. 

Insect of the Week – Twospotted spider mite (Acarina: Tetranychus)

This week’s Insect of the Week is the twospotted spider mite. This tiny mite is 0.5 mm long and has eight legs. It has a greenish, yellowish to orange oval body with two dark spots on its abdomen. To the unaided eye, it looks like a small speck. they feed on corn, soybean, dry beans, alfalfa, vegetables and fruit.

These mites overwinter in protected sites as eggs, immatures or adults depending on food hosts and habitat. Immatures and adults move to emerging plant hosts in the spring. They create webbing on the underside of leaves where they puncture cells to feed on cell contents. This feeding causes stippling, yellowing or browning of the leaves. Leaves may dry and drop which can further reduce crop yields.

Infestations start at the field edge and move inwards. Extended hot, dry conditions favour rapid population build up and exacerbate feeding injury.

For more information on the twospotted spider mite, check out our Insect of the Week page!

Twospotted spider mite – adult closeup
David Cappaert, Michigan State University,
Twospotted spider mite – stippling damage on bean
Whitney Cranshaw, Colorado State University,

Insect of the Week – Soybean aphid

This week’s Insect of the Week is the soybean aphid. This pest overwinters in the US and is blown into Canada, where winged females migrate to soybeans and produce several generations over the summer.

In 2016, 2.5 million acres of soybeans were planted in Alberta, Saskatchewan, and Manitoba. This amount is expected to rise in coming years. Thus, it is important to know how to scout for and manage soybean aphids.

For more information on soybean aphids, visit our Insect of the Week page.

Soybean aphid – adult (Robert J. O’Neil, Purdue University (wiki))

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