Tag Archives: insects

One Step Forward, One Step Back – Recent Changes in Invasive Species

January 13, 2014 admin Leave a comment

by W.D. McIlveen

The situation regarding invasive species is never static. Periodically we get good news mixed in with the gloomy reports of some new species that has appeared at our door. And so it is that we have some recent changes in local matters pertaining to invasive alien species.

Starting with the bad news first, the Asian Longhorn Beetle (Anoplophora glabripennis) which attacks a wide range of tree hosts had been declared eradicated from the Cities of Toronto and Vaughn. By 2003, the beetle had established a modest area of infestation in the boundary area between those municipalities. An intensive program was launched to eliminate the infestation by cutting and destroying all of the host trees within a 400 metre radius of the infestation. After detailed surveys of the area had found no more indications of the beetle for a period of five years, the pest was declared eradicated by the Canadian Food Inspection Agency (CFIA) on April 5, 2013. Unfortunately, a new infestation was detected in an industrial area on American Drive near Pearson International Airport in Mississauga on September 20, 2013. It is not known if the two areas of infestation are connected. They are not located too far apart so a connection cannot be ruled out though a new source of infestation is presumed. Multiple points of infestation are known at other locations in North America where similar eradication programs had been carried out. Some trees have already been cut down and it is expected that a similar form of eradication program will be undertaken to insure that the beetles do not spread.

On August 23, 2013, Credit Valley Conservation (CVC) reported that two round gobies (Neogobius melanostomus) were caught in the west Credit River at Hillsburgh. Additional surveys found at least 50 more of the fish just downstream. Previously, the species had been found only at sites in the catchment area where the water was closely connected to Lake Ontario, a location where the species has become well – established. It seems improbable that the fish had made it to Hillsburgh across dams and other obstacles without some sort of human intervention, whether intentionally or unintentionally. A program to manage the problem species needs to be developed in concert with MNR, CVC, local land owners and other stakeholders.

Not all news concerning invasive species is bad. In 2006, moth larvae were found feeding on swallow-worts in southern Ukraine. The larvae were brought to the Commonwealth Agricultural Bureau International (CABI), a highly recognized facility that studies biological control agents, in Switzerland for rearing and initial testing. The moths were found to be host-specific and very effective in controlling the host plant. Additional testing was done at the control facility at the University of Rhode Island to verify the results. The tests were so successful that the University petitioned the U.S. Department of Agriculture in 2012 to allow for the release of the moth to control the Swallow-wort problem. The US still requires one additional step before approval is granted but that approval appears to be easily achievable (after the current political financial situation is resolved in that country). The application though has met all of the conditions set by Canada concerning the release of a biological control agent. As a result, 500 of the moth larvae were released at infested sites near Ottawa. So far, the caterpillars appear to be surviving well and the populations are being monitored. In time, it is not unreasonable to expect to see the moths make their way to our area. While there are many areas in the Province where Swallow-worts are a problem, there are many places around Toronto (e.g. Don River Valley) where the populations are very dense. The moth is known as Hypena opulenta (Figure 10). It resembles a few other Hypena species that occur in our area; however, those other species do not feed on Swallow-wort. This similarity and any resulting confusion may hinder the monitoring of the spread of the species into our area but the presence of the distinctive caterpillars (Figure 2) feeding on the plants should be easy enough. Naturalists should be on the lookout for these caterpillars wherever the Swallow-wort is present though it may take several years to reach here on its own.

author - Scallen, insects/spiders

Mimicry

May 28, 2013 admin Leave a comment

by Don Scallen, Vice-President

People manage their appearance with clothing, jewelry and hair styles to present a particular image of themselves to the world.

Deception is often involved. A muscled, leather-clad, tattooed man may be a powderpuff, but his fearsome exterior projects a formidable – “don’t mess with me!” – presence.

Insects are masters of this bluff. There is a vast array of harmless flies and beetles for example, that have evolved to look like dangerous bees and wasps. This allows them to conduct their business with openness and swagger instead of cowering beneath a leaf or skulking in the undergrowth.

But, like everything in nature, mimicry is complex and nuanced. The viceroy butterfly famously mimics the poisonous monarch butterfly. For years it was assumed that the viceroy was free-loading on the monarch’s distasteful reputation, offering nothing in return.

As is often the case in science, this explanation proved too simple. Research revealed that the viceroy doesn’t taste good either, so the two unrelated species actually reinforce each other’s security.

The bumblebee serves as a common model for mimicry. The snowberry clearwing moth (left), unarmed and likely quite tasty, looks like a large bumblebee and no doubt gains some protection from this resemblance.

Some robber flies also look like bumblebees, but their motives extend beyond mere protection, to the sinister. Robber flies mimic the nectar sipping bumblebees to ambush their prey. They loiter around flowers, waiting for pollinators like bees, wasps and flies to sidle up to the floral bar for a drink.

Then they pounce. Imagine the surprise of the victim held firmly in the robber fly’s grasp: “But…but… you’re a bumblebee – you don’t eat meat – lemee go!”

Humans have come lately to the art of deceit. Insects have been practicing it for millions of years.

Read more by Don Scallen at his blog, Notes from the Wild

author - McIlveen, insects/spiders

Snow Fleas

April 28, 2013 admin Leave a comment

Late in winter almost every year if one is out and about in the woods, we will encounter an interesting group of tiny organisms on the surface of the snow. These are Snow Fleas (Hypogastrura nivicola). Snow Fleas, a species of Springtail, are very small insect-like creatures that are totally unrelated to true fleas that prey on dogs, cats, humans and other mammals. In fact they are no longer even considered to be insects. At one time, the group called Collembola were considered to be a primitive type of insect. Now, due to recent studies, they, along with two other groups, the Protura and the Diplura (two-pronged bristletails), have each been moved to their own Class equal in status to the insects. Collectively, these four groups make up the Subclass Hexapoda or ‘six-legged’ arthropods.

There are many species of Collembola. They are quite small, about one millimetre in length and most live in the soil where they are seldom encountered, at least knowingly by humans. They can be extremely numerous with populations reaching 250,000,00 per acre. They mostly feed on organic detritus, breaking down leaf litter and the like and aiding in the recycling of nutrients for plants.

Figure 2. Masses of Snow Fleas floating on water, Acton, April 30, 2013

The Snow Fleas represent the one Collembolan species that we do see fairly often. They appear in large numbers, and because their dark colour contrasts with the white snow surface, we take note. They tend to aggregate in small depressions such as old footprints in the snow. The depressions likely offer a microhabitat that is just a little warmer, is protected from the wind, and the snow is likely to be saturated with liquid water. In any case, the Snow Fleas appear in large numbers and look much like dust particles. If one looks closely, you can see them jumping about on the surface of the snow.

Figure 3. Close-up of Snow Fleas in Figure 2

These photos were taken on April 30, 2013 at a small vernal pool along the Guelph Hiking Trail south of Acton. The masses of Springtails floating on the water looked a lot like globs of oil. It is uncertain if these animals were at the end of their days or if they had trouble breaking free from the surface tension of the water. Some of them were certainly still alive and were jumping about. Nevertheless, the photographs give some idea of the abundance of the creatures.

Although they have legs to help them move about, Springtails are also equipped with an unusual abdominal appendage called the furcula. This structure is what gives the group its name. It folds beneath the body with the loose end tucked into a receptacle also under the body. The furcula is held under tension and when needed, the tension reaches a level that the end slips out of the receptacle. The furcula snaps against the substrate and this throws the Springtail into the air to escape.

Snow Fleas are able to live quite comfortably in the snow and survive low temperatures owing to a special glycine-rich protein that acts as a form of antifreeze. In addition to the important role in recycling nutrients noted above, Springtails have been reported to provide a valuable ecological service by moving spores of mycorrhizal fungi and destroying spores of plant pathogens. Certain species have been blamed for damaging alfalfa crops. They have also been put to use as indicators of soil contamination owing to their sensitivity to certain chemicals in the soil.

by W.D. McIlveen
Halton/North Peel Naturalist Club

author - McIlveen, insects/spiders

Pygmy Grasshoppers

April 28, 2012 admin

Particularly in Spring, a walk in the woods might turn up a very tiny grasshopper among the dead leaves. These are likely Pygmy Grasshoppers, not ‘baby grasshoppers’. They are also known as ‘grouse locusts’ or ‘grouse grasshoppers’ or in one case, a ‘frog groundhopper’. Pygmy Grasshoppers are members of the suborder Tetrigodea and most occur in the Family Tetrigidae. One exception is Tettigidea lateralis that occurs in the closely-allied Family Batrachideidae. The seven species that are known to occur in our area are listed in the following table and samples are illustrated in the attached pages.

These grasshoppers, as their name implies, are quite tiny with adults ranging from about 7 mm to only 14 mm (half inch) in length. Females are slightly larger than males. Because of their small size and generally cryptic coloration, they are easily overlooked. They can be of various colours, browns though gray and mottled, but never green. Their eyes are rather pronounced and the pronotum is often elongated along the back to cover the thorax. The antennae are short and they lack auditory and stridulatory organs. Wings may be long or short.

Although they can tolerate slightly drier sites, most prefer to live on the ground in damp, muddy situations, frequently close to water. They are reported to feed on vegetation debris and microscopic algae that accounts for their preference for moist habitats. Eggs are laid in soil or mud. Because they over-winter as adults, they are likely to be active shortly after the snow melts in the spring. Given the mild winter this year that gives prospects for an early start to the season, we could expect to see these little fellows out and about in the very near future.