Wednesday, June 19, 2013

Attracting and Creating Habitat for Native Pollinators, Part 2

By Laurie Sheldon

For the beginning portion of of this blog, please refer to the following link: Native Pollinators, Part 1

Creating habitat for pollinators means much more than knowing which color flowers a given insect is attracted to. It involves knowing the life span and understanding the forage and shelter needs of each individual pollinator at various stages of life. For that reason, I'll begin part two of this blog with a bit more detail about the life cycles of Florida's most important pollinators.

Pollinator Life Cycles
Although bats and birds CAN pollinate flowers, the majority of the world’s pollinators are insects. We can divide these insects into 4 major groups: bees and wasps, flies, butterflies and moths, and beetles. They all go through the same basic life cycle: egg to larva to pupa to winged adult. Where the eggs are laid, larva mobility, what they eat during their life stages, and duration of each stage is highly variable.

Bee: Eggs in protected brood cell in nest. Larvae not mobile, stay there a month. Larva defecates, weaves silk cocoon around itself and pupates in cell. Adult life is from 3 weeks to a year .

Fly: Eggs laid close to or on the food they need to eat and grow, which can include rotting wood, soil-dwelling invertebrates and aphids. Larval length varies due to weather, how palatable the food is, and time of year. Parasitic larvae defecate, usually killing host, then pupate either within or on host. Adult life ranges from a few hours to several weeks.

Butterfly: Eggs laid on or near caterpillar host plant. Larval stage varies due to weather, palatability of food and time of year. Wanders away from host plant to avoid predation, forms chrysalis and pupates. Adult life is usually only 1-2 weeks with a few exceptions.

Beetle: Eggs laid close to or on larval food, which may include rotting wood, soil-dwelling invertebrates and aphids. Length of larval stage varies due to weather, amount and palatability of food and time of year. May stay with food source or drop to ground and pupate in litter on soil. Short adult life ranges from a few hours to several weeks.

Wasps and Bees
Bees evolved from wasps 125 million years ago alongside flowering plants. Because of this, their nesting needs are very similar (see chart at right). Of all of the pollinators, the most important group is the bees – specifically native bees. What are some of the differences between native bees and honey bees (which are from Europe)? See the chart at the right (hey - it's a very useful chart!). Two of the most important differences are that (1) they are more efficient than non-natives when it comes to pollinating and (2) they are mostly solitary nesters, so they are not aggressive. There are 6 families and 360 genera of native bees in Florida. Their varied tongue length is a determining factor in selecting flowers to obtain nectar and pollen from; so is their overall size. Smaller bees cant travel as far for nectar or pollen as the big guys can, so be aware of which bees you have and how large they are when considering where to place an artificial hive or flowering plants. Further, some bees exhibit flower constancy, which means that they visit one particular plant species per foraging trip. This is great for pollination, because it means that pollen wont be wasted by being delivered to an unreceptive flower.

Bee cells, top to bottom:
polyester, mason, leafcutter
Nesting needs
So we know that bees and wasps spend most of their lives in their respective nests. What do these nests look like and where are they? First we can divide the nesting into two groups – solitary nests and colonial/social nests.

Solitary nests
constitute 90 % of Florida’s native bees, 70% of which are built in the ground; the remainder are built in wood or stems. Cactus bees (Diadasia spp.) and polyester bees (Colletes spp.) are solitary ground nesters, the latter of which gets its name from the waterproof, plastic-like glandular secretion it makes to separate its brood cells. Ground nesting bees often pile soil around their nest opening like ants do. Carpenter bees (Xylocopa spp.), mason bees (Osmia spp.), and leafcutter bees (Megachile spp.) are solitary wood/stem nesters. While mason bees separate the chambers of their nests with mud walls to protect the brood from predators, leafcutter bees protect brood cells in rolled up leaves or flower petals.

Bumble bees (Bombus spp.) - and some sweat bees (family Halictidae) - are colonial/social nesters. They typically occupy abandoned rodent nests or patches of dried grass, usually lined with soft plant material. Their colonies are annual, so by the end of the season most of the bees are dead; a few holdovers restart the process. If you are going to be stung by a bee or wasp, it will likely be a colonial nester protecting its family... that’s just how they roll.

Top: hover (Syrphid) fly
Bottom: Tachinid fly

Flies
Flies are generalist pollinators (visit many species of plants), so you might want to put that swatter down and let them go about their business. These insects are much more complex than the common housefly we've all seen and spastically waved our arms at. There are several that have mastered the art of deception (a.k.a. mimicry), disguising themselves as wasps (Syrphid flies) and bees (Tachinid flies) to try to avoid becoming another critter's main course. Very sneaky! While that still might not make you adore them or want to have one as a pet, at least give them the credit they deserve... they're responsible for pollinating some of our most recognizable and well-loved natives, including American pawpaw (Asimina triloba), goldenrod (Solidago spp.), and members of the carrot family (Apiaceae).

Above: to each its own
Below: Luna moth antennae
Butterflies & Moths
Butterflies need open areas to bask (e.g. bare earth, large stones), moist soil from which they may get needed minerals, and prefer flowers that provide a good landing platform. Fortunately, these can be provided without much effort. Butterflies will also eat rotten fruit and even dung (see image at left)... a good justification to leave those little messes in your garden alone. They are infinitely pickier where their offspring are concerned, as each species requires a specific "host" plant to provide the nutrients their caterpillars need to grow and eventually become butterflies themselves.

Moths are easily distinguished from butterflies by both physical and behavioral characteristics. Moth antennae never have the swollen tip typical of butterflies, and can often be beautiful and feather-like. Further, their bodies tend to be wider and hairier than butterfly bodies, and their wings are generally less colorful. Moths are generally active at night, when the white/pale colored flowers they pollinate are open and easiest to see. Butterflies, on the other hand, are diurnal and prefer brightly colored flowers.

Magnolia with Longhorn beetle
(l) and Flower beetle (r)
Beetles
There are over 4,675 species of beetles (Coleoptera) within the state of Florida, of which about 12% are endemic. Unfortunately, they've managed to develop a bad reputation because, to be honest, they act like that friend who can't hold their liquor. They're messy, frequently causing unnecessary damage to the plants they eat, they wander between different species, often dropping pollen, and they've a penchant for plants with large, strong scented flowers with exposed sexual organs. Such behaviors make them some of the least efficient pollinators out there, but let's cut them some slack... the natives that they pollinate (Magnolia, sweetshrub and yellow pond lilies) are so incredibly beautiful that they could make even the soberest among us feel a little dizzy.


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That's all for Part 2. You should now be comfortable with who the major pollinators are and what their lifestyles are like. Please check back with us for the third and final portion of this Pollinator-Week inspired blog, in which we'll learn how to turn your home landscape (or a portion of it) into a pollinator-friendly habitat. Wings up!
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Addendum: here's the link for Part 3.

2 comments:

John A Almada said...

This is going to be so important for the future.

The Jolly Bloggers said...

Thanks for recognizing that, John! We think so too.