An online resource based on the award-winning nature guide

Hymenoptera

Blueberry Stem Galls

3-29-17 blueberry stem gall IMG_7405Up to a dozen tiny black wasps (Hemadas nubilipennis) will emerge from this gall in the spring, around the time when blueberry bushes are flowering. After mating, the female wasp lays her eggs under the surface of the blueberry stems. Once she has completed her egg-laying, she climbs to the tip of the shoot and repeatedly stabs it, preventing further growth.

The plant reacts to the wasp’s egg-laying by forming a kidney-shaped gall. The majority of galls (up to 70%) are formed on stems within the leaf litter. These galls can be up to an inch in diameter, and they contain many developing larvae that feed on the walls of the gall and grow during the summer, overwinter as larvae, pupate inside the gall in the spring, and then emerge as adults when the blueberry bushes are in bloom in late May and early June. The adults are almost entirely females.

If a blueberry bush has many galls, it can be problematic.  A branch possessing a blueberry stem gall will not produce flower buds, and no flowers means no blueberries.

Naturally Curious is supported by donations. If you choose to contribute, you may go to http://www.naturallycuriouswithmaryholland.wordpress.com and click on the yellow “donate” button.


Carpenter Bees Hibernating

email-carpenter bee holes IMG_1408If your home, shed or barn has weathered, unpainted wood and is riddled with ½”-diameter, perfectly round holes, there is a chance that carpenter bees are hibernating in them. Carpenter bees resemble bumblebees in both size and appearance (a carpenter bee has very few hairs on the top of its abdomen, which appears black and shiny, whereas bumble bee abdomens are often yellow and hairy), but they are not social insects. Instead of having a common nest in which they live and raise their young, carpenter bees drill  holes in wooden structures or trees inside of which they chew tunnels that contain six to eight brood chambers for their young. After creating the chambers, the female carpenter bee places a portion of “bee bread” (a mixture of pollen and regurgitated nectar) in each one. On top of each pile of food she lays an egg and then seals off the chamber. The larvae eat and grow, pupate and emerge as adult bees in late summer. At this point they feed on nectar, pollinating a wide variety of flowers before they return to their tunnels to over-winter.

Naturally Curious is supported by donations. If you choose to contribute, you may go to http://www.naturallycuriouswithmaryholland.wordpress.com  and click on the yellow “donate” button.


Female Black and Yellow Mud Dauber Wasps Making Cells & Laying Eggs

8-19-16  mud dauber 028If you look closely at the ground directly in front of this female Black and Yellow Mud Dauber wasp you will see the clump of mud that she has collected and rolled into a ball with her mandibles.  This lump of mud will be carried back to the nest site in the wasp’s mandibles, and then used as building material to mold a cell.  After making the mud cell, the wasp then goes and locates spiders, stings them (paralyzing but not killing them) and brings them back to the cell, into which she packs them.  When the cell is sufficiently stuffed with spiders, she lays an egg and seals the cell with more mud.  She makes and fills several of these cells and typically covers all of them together with a final layer of mud.  When the wasp egg in each cell hatches, the larva has living spiders to eat that haven’t decomposed, due to the fact that they are not dead. Eventually the larval wasp pupates and the adult wasp chews its way out of the cell.

Naturally Curious is supported by donations. If you choose to contribute, you may go to http://www.naturallycuriouswithmaryholland.wordpress.com  and click on the yellow “donate” button.

 


Broad-leaved Helleborine Dispersing Pollen

8-10-16  helleborine pollinia 021Having known since childhood that most insects have only one pair of antennae, imagine my surprise when I came upon a hornet on Queen Anne’s Lace that appeared to have two:  a pair of slender, black antennae, and between them, a shorter pair of white ones.  A bit of research revealed to me that in fact, these white “antennae” were actually the pollen sacs (pollinia) of an introduced and somewhat invasive orchid, Broad-leaved Helleborine (Epipactis helleborine).

Broad-leaved Helleborine is entirely dependent on insects to spread its pollen, especially wasps.  It attracts them with nectar, which is said to have an alcoholic and narcotic effect which may help with the spreading of pollen, as an inebriated wasp is less likely to clean pollen off its body before leaving.   Helleborine also produces a chemical which other plants produce and use to signal that they are being attacked by insects. It is used purely as a ruse by Helleborine, in order to attract wasps, Helleborine’s primary pollinators, who arrive to fend off other insects, and end up inadvertently collecting Helleborine’s pollinia.

Unlike the pollen of most plants,  Helleborine’s pollen grains are so sticky that they cannot separate – thus, the entire package of pollen remains intact and is removed at one time.  Wasps are capable of reaching the plant’s nectar without disturbing the pollinia, but cannot crawl out of the flower without striking against and detaching them and in so doing,  getting them stuck to their heads.    Can you find the pollinia in the insert photograph of a Broad-leaved Helleborine flower (which has not been visited by a wasp yet)?

Due to computer issues, Naturally Curious will resume posts next Tuesday, August 16.

Naturally Curious is supported by donations. If you choose to contribute, you may go to http://www.naturallycuriouswithmaryholland.wordpress.com   and click on the yellow “donate” button.


Cellophane Bees Emerging & Mating

4-20-16  cellophane bee  205Cellophane bees are one of the first bees to emerge in the spring, sometime between March and May.  These solitary bees nest underground, often in close proximity to one another, with each female digging her own burrow off of which she creates several individual brood cells.  Each cell is lined with a cellophane-like secretion which is applied with her short brush-like tongue to the walls of the cell.  She then fills the lower portion of the cellophane sac with pollen, nectar and some glandular material, lays an egg and seals the cell with more cellophane-like substance and a bit of sand for a cap.  The female then goes on to repeat the process and digs another cell.

The egg hatches and the larva grows throughout the summer, feeding on the supply of nectar and pollen contained within the cell.  The larva metamorphoses in the fall and overwinters as a pupa inside the natal cell, emerging as an adult on a warm, sunny spring day.

Males, which emerge before the females, can currently be seen patrolling the area where last year’s burrows were constructed, flying just an inch or two above the ground, searching for emerging females digging themselves out of the ground.  When a female is spotted, she is often bombarded by one or more males, creating quite the cluster of bees.  One male prevails, mating takes place, and the cycle continues.

Naturally Curious is supported by donations. If you choose to contribute, you may go to http://www.naturallycuriouswithmaryholland.wordpress.com  and click on the yellow “donate” button.


Bald-faced Hornet Nests No Longer Inhabited (if you live where there has been a hard frost)

Mary Holland holding very large wasp nest, which was built above her houseIf you research bald-faced hornet nests you will find that their average size is often compared to that of a football or basketball. The maximum size is said to be between 14 and 18 inches in diameter, and up to 23 or 24 inches in length. The pictured nest (which hung 20 feet above the roof of my house) measures 14 inches wide and 29 inches long – far larger than the average hornet nest!

This entire nest was built in roughly four months. It was started by a queen bald-faced hornet that, after emerging from hibernation this past spring, chewed some wood fiber, mixed it with her saliva and created a few brood cells surrounded by one or more paper “envelopes.” She laid an egg in each cell, and fed the hornet larvae insects which she first masticated into tiny bits. When the larvae pupated and emerged as adult workers, they assumed the duties of nest building, food collection, feeding the larvae and protecting the nest, while the queen continued laying eggs in horizontal tiers of cells. This ongoing activity produced a colony of anywhere from 100 to 400 workers by the end of the summer. Shortly before the first hard frost this fall, the queen left the colony and found a protected spot in which to spend the winter. When freezing temperatures arrived, the workers all died, leaving a nest that will never again be inhabited by bald-faced hornets. (Thanks to Nick Burnham, who ingeniously managed to collect the nest for me, and Gary Trachier for the photo.)

Naturally Curious is supported by donations. If you choose to contribute, you may go to http://www.naturallycuriouswithmaryholland.wordpress.com and click on the yellow “donate” button.


Bumblebees Foraging Fall Flowers

10-5-15 tri-colored bumblebee IMG_1479With frost just a whisper away, and in some areas not even that, there are still hardy plants, many in the Composite family (goldenrods, asters, thistles, Queen Anne’s Lace, Yarrow), which defy the odds and optimistically send forth blossoms on the off chance that there are still pollinators on the wing. Fortunately for them, bumblebees can and do fly at much cooler temperatures than honeybees and other pollinators. When food is plentiful and outside temperatures fall below 50°F., bumblebees generally stay inside their nest and live off their stores. At times when food is scarce or stores are low, they will forage when the outside temperature is as low as 43°F. (In severe conditions they have even been known to vary their flying height to and from the nest to take advantage of any temperature differences.) Locally, Tri-colored Bumblebees (Bombus ternarius) have a near monopoly on the last vestiges of nectar and pollen (see photo).

Naturally Curious is supported by donations. If you choose to contribute, you may go to http://www.naturallycuriouswithmaryholland.wordpress.com and click on the yellow “donate” button.