Helpful Insects in the Garden

Do you have trouble determining which insects you see in your garden? Not sure which are helpful and which are harmful? Green Venture summer student Aaron, who studies etymology at university, has compiled a list of 5 helpful and 5 harmful bugs which are common in the garden. Take a look at this list of 5 helpful insects, find out why they are good, and look for them in your garden!

What: Bees, Flies, Moths and Butterflies – Pollinators

Why they are good for the garden: Pollination is a needed service for any garden. The pollinators such as bees, hover flies and butterflies allow plants to reproduce, fruit, and genetically grow. As these pollinators land on the flowers surface, the pollen on the stamen (male parts) gets transferred onto the insect (or collected, in the case of bees) and as the pollinator flies to the next flower some of that pollen is transferred to the pistol (female parts). This pollinates (or fertilizes) the plant, allowing for the growth of the seeds and fruit.

What: Assassin Bugs

Why they are good for the garden: Assassin Bugs are a great predator for natural control of insect pests in gardens. With their needle-like mouth parts they paralyze, inject liquefying enzymes into, and then suck up the internals of their prey. They feed upon any herbivorous insect pests you can think of, from aphids, to potato beetles, to caterpillars. They can be quite large (as big as 4 centimetres in length) but they are harmless to humans, if left alone. Assassin bugs can be found on the underside of leaves, stalking prey and keeping camouflaged.

What: Lady Bird Beetles

Why they are good for the garden: Lady Bird beetles are one of the best known natural controls for aphids, and have been used for centuries on crops for this purpose. Both their larval forms and adult forms are predatory, and can eat up to 400 aphids as larvae and up to 5,000 aphids in a one year lifespan. A single Lady Bird beetle can also lay up to 1,000 eggs. Unfortunately, due to their popularity, many species were brought over to increase their control abilities. One of the most well known and most common lady bird beetles in North America, the Asian Multicolored Lady Beetle (Harmonia axyridis), is now an invasive species and out-competes native Lady Bird beetles for resources, thus endangering them (see pictures below for the difference between the two species).

What: Parasitic Wasps

Why they are good for the garden: Parasitic wasps have gotten a lot of recent attention in Integrated Pest Management, especially in greenhouses, for the control of many herbivorous insect pests. Parasitic wasps have even become available for purchase to every day gardeners. If purchased, they are shipped on strips of card board that have eggs or pupae glued to them and can be hung in the garden. The wasps will then hatch, fly to the pest which will be their host, and use their ovipositor (egg laying structure) to inject eggs into the host. The larvae hatch and eat the pest from the inside out, causing the adult wasps to emerge from the dead host, fly away and parasitize more of the pest, thus controlling the population. These parasitic wasps are very host specific, so the ones on the market will not target anything other than the pest needing control. The wasp can parasitize a variety of species from tiny aphids to large caterpillars.

What: Ants

Why they are good for the garden: Ants are one of the best beneficial insects to have in a garden. Mound building varieties of ants act as great natural tillers; with their complex tunnel excavation, they bring up soils from lower horizons and help mix in nutrients from the surface. They also can help in plant growth, as they take seeds they find at the surface and place them in certain chambers of their nest to grow. Some species harvest fungi, which helps in providing valuable nitrogen for the soil, which is an essential nutrient for plants. They are also fairly territorial, and will ward off large unwanted pests such as caterpillars. That being said, some ant species will tend to aphids, farming them for their sweet excretions, and causing their population numbers to explode at a faster rate. If this is the case, be sure to handle an aphid problem quickly, but leave the ants be!


Stay tuned for the next blog about which insects can be harmful in your garden!


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Written by Aaron F. and edited by Rebecca J.


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