Dutch elm disease (DED) is a fungal infection that has wiped out American elms in most of their natural range in eastern North America. Alberta is one of the last places on earth that host healthy stands of these graceful trees. The deadly Dutch elm disease is spread by one of three closely related beetles [...]
Photo by: Steven Katovich, Bugwood.org
The larvae of this insect look like a caterpillar. They eat the needles of Spruce causing damage. They have yellowish bodies and yellow/brown heads. The new needles are attacked first. They are chewed down almost to the base before the insect moves on to older needles. A severe infestation, lasting for 3 or more years [...]
In Calgary, young spruce trees are the typical host for the white pine weevil. This weevil is a small brown beetle with a long ‘snout‘. Although the adult beetle is seldom noticed, the effects of the grubs, feeding at the tops of spruce becomes apparent in mid-summer as the leader dies. Key Points Damage usually [...]
Spider mites become active in mid-May and begin feeding on the needles of spruce. These mites are easily moved to other trees by wind or by hitching a ride on the bodies of birds or other animals. Infestations are more likely during dry conditions. There are many generations of mites born each year. Key Points [...]
The poplar bud gall mite is a tiny mite that would never be noticed except for the galls (swellings) it forms on poplar twigs. These tiny mites are eight-legged creatures related to spiders which feed first on leaf buds. While feeding, these mites stimulate the poplar to produce a hard lumpy gall that encases the [...]
It may not look like an insect, but the pine needle scale is one species in a group of tiny insects called armoured scales. Beneath the scale-like shell the tiny insect sucks the sap from needles. Oddly, pine needle scale is more common in Calgary on spruce than pines. Once on a suitable needle, the [...]
Oyster shell scale on Cotoneaster
This insect has become a major issue in Calgary over the past number of years. Oystershell scale is hardly recognizable as an insect. On close inspection it looks like a tiny oyster shell. It is one species of a group called armoured scales. Oystershell scale can attack fruit trees, lilacs, ash and elm but in [...]
European Elm Scale has become a large problem in Calgary in the last decade. Symptoms are not obvious unless the infestation level is quite high. Prevention is tough when untreated trees are nearby as the insects move fairly easily between trees. As with most insects and disease, a healthy tree is less likely to be [...]
These microscopic mites feed on the foliar tissue of plants which causes them to form a gall or other deformation on their leaves. They transfer from plant to plant via wind, birds and flying insects. They are generally considered a parasite since they rarely kill plants. Key Points Mainly considered to be an aesthetic issue. [...]
Cottony Ash Psyllid showed up in Calgary about 20-25 years ago. Black Ash and Manchurian Ash are most affected by this insect. Eggs from the previous year hatch in June and nymphs feed until about mid-July. Now adults, they lay eggs in July and early August which hatch and the resulting nymphs begin feeding. When [...]
There are many species of caterpillars that feed on tree leaves. Most are specific about what type of tree they feed on, so an outbreak of caterpillars feeding on an elm will likely not defoliate a nearby Schubert Chokecherry for example. Some species feed on a variety of trees and shrubs, as well as herbaceous [...]
Bronze Birch Borer is another insect that had not been seen commonly in Calgary but has shown up in greater numbers over the past few years due to the added stress that erratic weather has caused the trees in Calgary. The adult female bronze birch borer is an elongate beetle with a metallic greenish black [...]
Birch leafminer is one of the most common leaf problems that distress homeowners. This insect was not a major issue for many years but has definitely shown up in larger numbers recently. Birch leafminers are the caterpillar-like larvae of at least 3 or 4 species of tiny sawflies that mine birch leaves. Sawflies are named [...]
Aphids like to feed on the soft growth of almost any plant. This includes most trees, though in Calgary Birch (Betula), Willow (Salix), Maple (Acer) and Mayday (Prunus padus) seem to be most affected. Aphids are able to reproduce without males which can lead to huge populations some years. Heavy populations can be tough to [...]
This insect is becoming a more serious pest to Ash trees in Calgary. Hot weather and a lack of water can cause stress for Green Ash and make them more susceptible to infestation. The Western Ash Bark Beetle lays its eggs in twigs and branches. Larvae develop and start galleries in the stem. As feeding [...]
Ash Leaf Cone Roller had become more established in Calgary over the previous decade but hasn’t been as bad the past few years. It mainly affects Green Ash trees (Fraxinus pennsylvanica). While the insect is in the caterpillar stage the insect rolls the leaf into a cone shape, causing the objectionable look of the tree. [...]
Has the top of your Spruce tree ever looked like this? The insect that causes this damage is the White Pine Weevil. It’s name is deceiving, at least in our area, here it mainly does it’s damage to Spruce trees. This weevil is a small brown beetle with a long ‘snout‘. Although the adult is [...]
We have been seeing a number of hedges around Calgary the last few years that are severely infested with Oystershell Scale. The damage appears as large sections of the hedge that “dieback” or fail to leaf out due to the infestation. This results in a very patchy, ragged look. As you can see in the [...]
