Springing to life, part one

Just in time for the first days of spring, the Texas bluebonnets spread from sparse glimpses of blue to cover all the nearby meadows.

A field of Texas bluebonnets (Lupinus texensis) in bloom.

Though the bluebonnets were not yet swarmed with visitors (the way they were last spring at the peak of their bloom), I found a variety of insects on the blossoms, including honey bees, lady beetles...

A seven-spotted lady beetle (Coccinella septempunctata) on a bluebonnet inflorescence. 

...and even large, menacing wasps.

A paper wasp (Polistes sp.) feeding from bluebonnet flowers.

However, the many butterflies that also appeared with the mild spring weather were mostly attracted to another type of flower.  To be continued...

A caterpillar in the bonnet, continued

As I continued my search for the seed pod raiders, I soon came across more plausible suspects than the lady beetle. I found numerous caterpillars not only suspiciously near both old holes…

... and fresh holes...

… but also chewing the holes…

… and feeding from within the seed pods.

Because the seeds are provisioned with enough nutrients and energy to support the initial growth of a new plant, they make tempting meals -- even considering the effort required to tunnel through the protective pod.  Thus, by the time the seed pods finished maturing, a significant proportion appeared to have been plundered by the large population of hungry caterpillars.

A caterpillar in the bonnet

The bluebonnets attracted many more visitors than just bees this spring.  Among these other visitors were caterpillars – which came to feed on, rather than from, the flowers.

A caterpillar feeding on the buds of a Texas lupine (Lupinus texensis).

However, the flowers were not the most enticing part of the bluebonnets for herbivores.  Soon after the seeds pods began maturing, they started to become riddled with holes.  Meanwhile, the seeds that should have been developing inside were damaged or even completely missing.

Texas lupine seed pods after a seed predator attack.

The first insect that I found in the vicinity of the holes was a lady beetle. 

A seven-spotted lady beetle (Coccinella septempunctata) by a freshly chewed hole in a Texas lupine seed pod.

Yet, nearly all lady beetles, including the one pictured here, are primarily predators of other insects, not of seeds.  Therefore, it seemed unlikely that the lady beetle was the culprit.  Then, what was making all the holes?  To be continued…

A bee in the bonnet

For the past couple of weeks, most of the open areas around my apartment have been carpeted (somewhat treacherously) with the Texas state flower -- the bluebonnet.

A field of Texas bluebonnets (Lupinus texensis) and a few other flowers too.

Although the bluebonnets themselves are innocuous, they have been attracting swarms of both honey bees and photo-op seekers.  While watching the former and trying to ignore the latter, I noticed that the bluebonnets are remarkable for more than just their vibrant color.

A honey bee (Apis mellifera) approaches a bluebonnet.

Each flower is blue with either a white or a purplish inner spot; however, the color of the spot is not random.  Only the youngest flowers, those at the top of the spike, have a white center.  As the flowers age, their spots turn purple, similar to how the markings on horse chestnut flowers change from yellow to pink (and likely for the same reason). 

A honey bee collecting nectar.

The structure of the bluebonnets is also impressive.  The actual reproductive parts are all hidden away inside the flowers, so how does pollen get picked up and deposited?  Unlike the bees that I have seen squeezing inside some other lupine flowers, a honey bee visiting a bluebonnet just lands on top of the flower.

When the honey bee lands, the flower opens, exposing the stigma and anthers.

The weight of the bee then pushes the flower open.  In the process, pollen from the flower's anthers is rubbed onto the bee and pollen from the bee may get stuck to the flower's stigma.  The flower stays open for a moment after the bee leaves, then snaps back into place until the next visitor arrives.

The early bee gets the nectar

Though the European wool carder bees were visiting leaves, most of the bees in the garden were focused on flowers.  On sunny (and very hot) afternoons, the garden was full of bumble bees, honey bees, and a variety of smaller, solitary bees.  However, not all flowers -- even on the same plant -- were equally attractive to these bees.

Sedum flowers in full bloom.

Some, particularly the smaller bees, would pass over wide open flowers, electing to squeeze their way into those flowers that were just beginning to open.

A small bee visiting an opening sedum flower.

The bee emerging from the sedum flower.

Although more difficult to access, these flowers were more likely to have a fresh supply of nectar and pollen available to the bees.  Certainly, the two bees pictured here had been quite successful in collecting pollen -- just see the yellow legs of the bee above and the orange underside of the bee below.

A leafcutter or mason bee (Megachilidae) visiting a lupine flower.