Royal Alberta Museum: Invertebrate Zoology - Bug Facts

[Caterpillars and Other Immature Insects]

Fact Sheets: Commonly Observed and Asked About Insects and Spiders Found in Alberta

Wee Harlequin Bug (Cosmopepla bimaculata)

Wee Harlequin Bug
Credit: Terry Thormin

<I>Perillus exaptus</I> - a similar looking stink bug

Perillus exaptus - a similar looking stink bug
Credit: Terry Thormin

INTRODUCTION

The Wee Harlequin Bug is a member of the stink bug family. Like most members of this family, it has a chemical defence that results in a vile smell, which is the reason for the family name. It also displays classic warning colouration of black and red.

IDENTIFICATION

The Wee Harlequin Bug is also known as the Two-spotted Stink Bug and the Twice-stabbed Stink Bug. Although there are a number of other insects that are black and red, the shield-like shape of this insect, and the position and shape of the red markings should be sufficient to allow a positive identification. Adults are about 5 mm long. Nymphs, which are often found in large aggregations, are also black and red and are similar in shape to the adults, although they lack wings.

DISTRIBUTION

This stink bug is found throughout Alberta, and is distributed throughout most of North America.

TIME OF YEAR

Adults are present from about mid-May to early September.

HABITAT AND HABITS

This insect is a plant feeder, piercing the plant tissue with its needle like mouthparts, using enzymes to dissolve the cell walls and then sucking up the resulting soup. Because it feeds on a wide variety of plants, including milk thistle, echinacea, asparagus, oats, mint and goldenrod, it is found in a wide variety of habitats. Adult females will lay their eggs in tight clusters and protect them until they hatch.

SIMILAR SPECIES

Although there are a number of other stink bugs found in Alberta, there is only one that looks at all similar to the Wee Harlequin Bug, and that is the less common Perillus exaptus. We have included a photo of this species for comparison. As well the Box Elder Bug, which is not a stink bug, looks somewhat similar, although it is more elongate in shape. For more information on the Box Elder Bug see the write-up in this section.

COMMENTS

Individual Wee Harlequin Bugs usually do not attract enough attention that the observation results in a phone call to the museum. Large aggregations of nymphs, on the other hand, often do arouse curiosity. This species only rarely reaches population levels that result in its becoming a serious pest. In some areas it can be a pest on asparagus and echinacea.

Note: We cannot provide advice on controlling insect pests. If you need more information beyond what has been provided here, we suggest you either search further on the web, or talk to a local exterminator.

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For more information on this bug, please contact the Bug Room.
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Last update: August 19 2004