April

by Master Naturalist Pam Johnson.

As I observe the plants and animals and insects interact on JDCF preserves, I notice so many connections if I take the time to watch.

Mutualism is defined as a symbiotic relationship between different species where all participating organisms benefit from and may depend on each other for survival. The mutualistic benefit that plants and bees share is the most familiar example. The plant provides nectar and the bees provide pollination services for the plant.

Some pollinators are specialists preferring certain plants and others are generalists. What I have observed is that our native plants attract the most insects.  Pollinators need native plants and native plants need pollinators. When pollinators feed on the nectar or pollen in flowers, they brush against the flower’s anthers (the pollen-producing tip of the stamen) , picking up pollen that they then carry to the next flower – usually of the same species.

This pollinator-plant relationship evolved over time. Flowers evolved traits that entice specific pollinators, and pollinators evolved traits that help them feed more efficiently. Some of these relationships are so specialized that a plant may rely on a single pollinator species, and vice versa. Non-native plants may be inedible to native pollinators or may not meet pollination needs.

Watch: Bumble Bees and Pollination of Native Plants  This 10-minute video features stunning close ups of bees gathering pollen from Shooting Stars like those found at Rutherford Refuge.  See May events for a scheduled walk of Rutherford refuge.

April Phenology to look for on JDCF preserves:

Insects

• Bumblebee queens emerging from hibernation
• Comma & Question Mark butterflies – (overwinter as adults)
• Mourning Cloak butterflies – (overwinter as adults)
• Spring Azure butterflies

Mourning Cloak Butterfly

Bumble Bee Queen – Virginia Bluebells

Comma Butterfly

Birds

• Catbirds arrive
• Brown Thrashers arrive
• Wood thrushes arrive
• Barn Swallows arrive
• Great Egrets arrive
• Field Sparrows arrive

Gary Catbird

Great Egret

Yellow-rumped Warbler

Flowers

• Common Lilacs begin to bloom
• Wood Betony  begin to bloom
• Large White Trilliums begin to bloom
• Wake Robin Trilliums begin to bloom
• Golden Alexanders begin to bloom
• Shooting Stars begin to bloom
• Meadow Anemones begin to bloom
• Virginia Bluebells begin to bloom

White Trillium

Wake Robin Trillium

Bloodroot

Trees/Shrubs

• Black Cherries begin to bloom
• Chokecherries begin to bloom
• Oaks begin to bloom

Oaks require pollen from a different oak of the same species to fertilize female flowers and initiate acorn development. Most oaks won’t begin to flower until they are at least 17 years old. Male flowers are catkins which look like dangling earrings. The female flowers are tiny and often hidden high in the canopy.

Galls are abnormal, tumor-like swellings or growths on plants and are another example of insect-plant relationships that are visible in April. Their formation can feel like science-fiction. Imagine an insect laying eggs just under your skin. Within a week larvae develop and begin to feed. Soon a large growth appears developed by taking over regulation of stem cells. This nursery is fed by your blood stream. When the larvae are ready to emerge as adults, they eat through the skin. The formation of galls on plants follows a similar sequence of events.

Galls

The formation of galls in nature can be between plants and insects, mites and nematodes and plants. Gall inducing insects are host specific. For example: the Goldenrod Gall Fly (Eurosta solidaginis) has two adaptations; one that prefers Late Goldenrod and one that prefers Tall Goldenrod. They use chemical sensors in their feet to distinguish between species. Their ovipositor can also detect whether they are inserting eggs into the correct plant and withdraw if it is not. (North Shore, p. 196 – see references)

Adult gall insects emerge in spring, timed with new plant growth that provides ideal egg-laying sites.
A single gall on goldenrod can cut seed production by half, yet galls rarely kill the plant. Over millions of years, plant and gall insects appear to have reached a truce: the insect receives protection and food, and the plant survives.

Some galls even benefit their host plants. For example, fig trees rely on a specific species of fig wasp for pollination. Fig wasps lay eggs inside the short-styled female flowers. These galls nourish the developing wasp larvae, which develop alongside the seeds. This process is part of a 70–90-million-year-old mutualistic relationship between figs and wasps. The adult wasps, in turn, pollinate the fig flowers, ensuring the tree’s reproduction.

Galls come in many forms – round, spiky oblong, or cup-like – and often help me identify both the plant and the insect that created them. They also provide food for other species: birds feed on galls in winter, and anglers sometimes use the larvae as bait.

Reference Reading:
A Naturalist at Large by Bernd Heinrich.
North Shore Natural History of Minnesota’s Superior Coast by Chel Anderson and Adelheid Fischer.