The Pollen-Bellied Leafcutter

Most people are familiar with bees that collect and carry pollen on their legs in either specialized pollen baskets called corbiculae or on long bristles called scopae. Only females have these structures, and they carry pollen back to their hives or nests, where the sweet, nutritious bits are used to provision egg chambers for their (or their queen's) offspring.

A slightly different strategy is used by bees in the Leafcutter family (Megachilidae). The female Leafcutters have scopae on the underside of their flattened abdomen, which collect pollen as they forage and give their underbelly a dusty, glowing golden hue. This method of pollen collection is a bit sloppy, and the pollen scatters easily as the bee forages, making her a very good pollinator (at her own expense--she will need many more foraging trips to supply her egg chambers compared to honeybees, who moisten the pollen with so it sticks together and stays tidily within the pollen baskets).

Leafcutter bees are solitary, and each female constructs chambers for her eggs in cavities found in wood, plant stems, or sometimes in the ground. Their name comes from their habit of neatly chewing circular bits of leaf that are used to line and separate each egg chamber (one egg and a supply of "bee bread"  in the form of pollen or a pollen/nectar mix). The larva with survive on these provisions within the chamber through several instars, or molts, until they pupate and emerge from the chamber as an adult.

The Leafcutter is a busy bee, and a wonderful neighbor. Consider her before cleaning up stems and branches in your garden, as she may make use of them for her eggs. You can also purchase houses, or bundles of tubes, to encourage her to make her brood chambers near your garden. 

The Northern Paper Wasp

Poor wasps. Reviled as a menace to humanity; sprayed and poisoned and swatted without any pang wherever their homes are sighted by humans. The sleek, dangerous alter-ego to the fluffy, friendly bee.

I encountered this Northern Paper Wasp (Polistes fuscatus) foraging for nectar along the Greenway, mingling with a motley assortment of bees, flies, beetles and others enjoying the last morsels of sweetness before the waning warmth of fall gives way to a winter chill that sends most of them to their peaceful, eternal rest....

But I digress. This wasp charmed me, starting with the adorably curled tips of its antennae and the striking pattern on its abdomen: black and yellow stripes, with a pair of smoky two-tone spots near its thorax. Its slender frame and waist and lack of hair on its legs and body distinguish it from its bee relatives. This (or rather these--the photos show two different wasps, as can be seen by the markings on the thorax) appears to be a male, based on the curled antennae and yellow face, though not all sources remark upon this as a distinguishing factor between males and females. The absence of a stinger is common to all male wasps and bees.

While foraging wasps generally don't pay much attention to paparazzi and other humans, it is a different story if one were to threaten their nests. Paper wasps get their name from their elaborate nests constructed of bits of wood, chewed to a pulp and formed into papery chambers where one or more dominant females will lay eggs. Theirs is a complex society, with elaborate social hierarchy complete with recognition of nestmates based on both behavior and individual facial features.

Nests will be aggressively defended both from predators and other unrelated wasps. The egg-laying queen(s) are among the most vigorous of the defenders, since their genetic investment in the eggs and larvae is the greatest. In spite of the risk, wasps can be valuable allies in the garden, where they will capture caterpillars and other pests to feed to their young.

 

Vanessa Invasion

If you've set foot outside in the past couple of weeks and found yourself in the vicinity of any flowers, you have probably noticed an abundance of medium-sized, orange and black-colored butterflies swarming sedums, goldenrod, asters, and just about any other flower they can find.

These are Painted Lady butterflies, (Vanessa cardui), a migratory species that has begun its return trip to Mexico and California as its more famous counterpart, the Monarch, will begin in a few weeks. Also similar to the Monarch, the Painted Lady have multiple generations each summer before returning to their overwintering grounds.

Due to favorable conditions earlier this year, the Painted Lady population has exploded, increasing drastically through each generation over the summer. At Reiman Gardens in Ames, their regular count from last year tallied around 20 individuals, but this year the number exploded to 747 individuals.


Why does the Monarch population struggle year to year while other butterflies thrive? It is the old story of a specialist versus a generalist: where Monarchs utilize only a single type of plant--milkweeds--as hosts for their caterpillars, Painted Ladies are not nearly as discriminating and may use any of over one hundred different species as hosts.

In addition, habitat loss has struck Monarchs particularly hard and left them with a very small overwintering patch in Mexico, where they are vulnerable to winter storms. Painted Ladies, with a range throughout much of the globe, are better able to withstand occasional local disasters as their population is not centralized in any single place.













Sources/more information:

• http://whotv.com/2017/09/08/painted-ladies-enjoy-iowas-great-fall-like-weather/
• https://www.butterfliesandmoths.org/species/Vanessa-cardui

A Rare Sighting

Not long ago, I would have strolled past this botanical unicorn without a second thought. I probably wouldn't have even noticed it, hunkered down in the mowed strips alongside the Greenway, pearly white leaves gleaming in the sun.

But now--now I know to stop and take a closer look. It was an albino--I tentatively identified it as a smartweed (perhaps Swamp Smartweed, Persicaria amphibia), with tapering leaves and fine short hairs covering the leaves and stems. A couple feet away was were some standard-issue smartweeds, looking for all the world like my ghostly mutant only bearing the expected green tint.

Given that the green coloration in plants is due to chlorophyll, the pigment that makes photosynthesis possible, how can a pure-white plant like this one survive? Normally an albino seedling might grow briefly until its food stores from the seed are depleted, then starve when it is unable to feed itself. Some albinos, such as the famed albino redwoods, can survive for years by parasitizing the roots of nearby normal redwoods. This allows the albino to tap into the root system of other trees that photosynthesize normally, presumably without deleterious effect on its hosts.

I suspect my albino smartweed has a similar understanding with its neighbors: perhaps it is able to sustain itself by tapping into the roots of the nearby plants, or it is itself a mutated shoot from underground rhizomes of a nearby parent. Though it seems to be surviving well enough right now, save for some singed leaf-tips, it likely will not be long for this world. The combination of mowing and bright sunlight will stress its already fragile leaves, and its inability to photosynthesize is something of a deal-breaker in the botanical world.

Possible host for the
nearby albino

I confess to a momentary temptation to dig up the albino and bring it to the safety of my yard, before realizing that such an effort would probably hasten its demise. Unless its generous host could be identified and carried off in tandem, the little white weed would certainly starve on its own.

So my ephemeral, unpigmented friend will be all the more lovely for its brief stay on the Greenway.