Mystery Bug

Jul 14, 2011

by Lorraine Julien

Photo: Birch Shield Bug

I’ve learned a lot about bugs this past few weeks. I was lucky (not sure if that is the right word!) enough to find a strange looking bug perched on the side of one of my planters recently. I didn’t realize then but some of these bugs can be quite destructive to plants, literally sucking the life out of them.

After a lot of research, I’m quite sure the bug on the planter (as shown in the picture) is a Birch Shield Bug (Elasmostethus interstinctus – order Hemiptera). Since Stink Bugs and Shield Bugs share a similar shield-shaped body, I initially thought it was a Stink Bug but couldn’t find anything that matched my photo. The search was made more difficult because the Birch Shield Bug is very similar to some other Shield and Stink bug species, including the Juniper and Green Shield Bugs. If you read this column, and you are knowledgeable about bugs, I’d really appreciate hearing from you as to whether or not you confirm my findings.

The Birch Shield Bug reaches a length of 9 to 11 mm, similar in size to many other Shield Bugs. Larvae are found, and feed, mainly on Birch as the name implies.

These bugs over-winter as adults, emerging and mating in the spring. Eggs are laid in May and June and generally hatch in August. Adults love low bushes, preferably in the sunshine. When I photographed it on June 24, my bug was sunbathing in dappled sunshine, under a clump of birches, near the east end of Kashwakamak Lake.

Apparently these little bugs are found all over the northern hemisphere throughout Europe, Asia, Japan and North America. Canadians and Americans usually refer to this species simply as the Birch Bug.

I thought at first that my bug could be a Harlequin Stink Bug, but, after some investigation, I found Harlequins are coloured very differently with a black back and bright patterns in red, yellow or orange. These pest bugs can be quite destructive while some Stink Bug species are actually beneficial for the garden and feed on caterpillars. The Harlequin is fairly common and about 10 mm in size. The Green Stink Bug, while larger, is also quite common and is an overall soft green colour. There’s a good chance you’ve seen this fellow in your garden. Also common is the Brown Marmorated Stink Bug which is also larger at 15 mm.

Shield Bugs and Stink Bugs have no chewing mouthparts but do have tube-like beaks called “rostrums” attached to their heads. The rostrum has four thin, sharp needles in it. The needles are used to pierce plants, and some insects, to suck up the sap or juice.

If you find these little fellows in your garden and want to get rid of them, the best way is to just pick them off the plants and drop them into soapy water. My little bug was camera shy and I was unable to find him/her later.

I thought I’d seen everything when one day recently, I noticed a Harlequin Bug necklace for sale on E-Bay for $4.99! The little bug was encased in some type of clear acrylic.

Please feel free to report any observations to Lorraine Julien at This email address is being protected from spambots. You need JavaScript enabled to view it.  or Steve Blight at This email address is being protected from spambots. You need JavaScript enabled to view it.