Posts Tagged ‘Insects’

Bee populations have been having a hard time for a while now. Species of bee all around the world have experienced significant population declines that have persisted for decades. But it has been difficult to get a sense of the full magnitude of the issue since so many of the bee population studies focused on a single species, or a relatively small geographic area.

In 2020, researchers at the National University of Comahue in Argentina took a more global look at the loss of bee diversity. These researchers published a paper used data from the Global Biodiversity Information Facility which is a platform where researchers and citizen scientists can record sightings of bee species, and that is available to the public.

By examining observations of bees around the world they found that the number of bee species observed from 2006 to 2015 was only about 75% of the number of species observed before 1990. That is not a very long period of time, and these declines were despite the fact that more and more observers are adding more and more observations to the platform each year. To clarify, this does not mean that 25% of the world bee species have gone extinct, but it does mean that they have become so rare that people are not encountering them. Although, becoming extinct is one potential reason for no longer being observed.

One of the bee species, in particular, that has declined rapidly is the Rusty-patched Bumble Bee (Bombus affinis) which was once found across much of the mid-western and northern USA. This species has declined by nearly 80% since the late 1990s. This decline lead the United States Fish and Wildlife Service to list the species as federally endangered in 2017. This was the first species of wild bee in the continental USA to ever be federally listed and so gain the protection of the Endangered Species List (several species of bee native to Hawaii have been given this status prior to the Rusty-patched Bumble Bee).

Rusty-patched bumble bee on culver’s root at University of Wisconsin–Madison Arboretum. Photo: Susan Day/UW–Madison Arboretum.

The listing of the Rusty-patched Bumble Bee and the research on the dramatic and sustained reduction in abundance of global bee biodiversity both serve to highlight the loss of bees and other insects. This is an often overlooked section of lost biodiversity. The extinction of a rhino species is much more eye-catching than the extinction of a bee species. But loosing bees and other insects is having, and will continue to have, profound impacts on the natural world around us, and so should not go unnoticed!

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In the last week, I have been seeing some impressively large insects right around our place in West Sacramento. The first was a few days ago, when I was out walking around our little condo complex with my wife and daughter enjoying the evening air and each others company. I looked up at one of our walls and saw a huge insect walking along the wall. It was about 2.5 inches long, bright green, and its body looked very leaf-like. I thought it was a katydid of some kind, but having never actually seen a katydid before, I was not confident. Well, I looked it up, and sure enough, it was a California Angle-wing Katydid (Microcentrum californicum). My first!

Copywrite Natalie McNear

California Angle-wing Katydid (Copywrite Natalie McNear)

It turns out that there are six species of angle-wing katydids in North America. The California Angle-wing is the smallest of the six and is only found in California and Arizona. Adult katydids appear in late summer and fall and are mostly active at night. They are attracted to lights, but not strongly, so you are unlikely to find lots of these insects gathered together. The males attract females by rubbing their front and hind wings together (not a wing on their leg as is often thought). Once the female is close, she will respond with calls of her own and the two individuals will close in on each other through this back and forth conversation. Both sexes perceive sound through small slits in their front legs. I am very much looking forward to spending some time outside and listening for these stradulation calls. I may try to get some recorded. If so, I will attempt to post the recordings here.

The second large insect encounter happened yesterday. Again, my wife, daughter, and I were out walking the grounds when a really big, black wasp flew past me. It was at least an inch long, and was cruising back and forth across the lawn just above grass height. It was completely black. Its body was black and shiny metallic, and its wings were a smoky black as well. After looking this one up, I found that it was a female Great Black Wasp (Sphex pensylvanicus), and no I am not making that name up. This is only the second Sphex wasp I have ever seen!

Great Black Wasp (Copywrite Paul A. Scharf)

Great Black Wasp (Copywrite Paul A. Scharf)

Sphex wasps are diggers. The females dig underground burrows in which they lay their eggs and then go out and hunt for insects for their young to feed on when they hatch. The Great Black Wasp has a very precise way of paralyzing their prey with exactly three stings; one to the neck and two to the thorax. This paralyzes their prey without killing it so that it stays fresh longer for the young wasps. Interestingly, their preferred prey are Orthopteran insects (such as grasshoppers and katydids)! Great Black Wasps are found across most of the continental USA and into parts of northern Mexico. As an interesting side note, the Great Black Wasp was the subject of the first insect article written by a native of the new world (John Bartram of Pennsylvania) to be presented at the Royal Society in 1749.

So cool to see and learn about these impressive animals!

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I have recently been really enjoying watching the Valley Carpenter Bees (Xylocopa varipunctata) around our place in West Sacramento. These bees are the largest species of bee in California, and they are not messing around. They are huge! The females, which are completely black and very dramatic looking, can get up to just over an inch long, and the males, which are yellow with green eyes, are only slightly smaller!

Carpenter Bees are in the genus Xylocopa, the large carpenter bees. There are about 500 species in this genus, worldwide. Five of these species are found in North America and three of them are found in California. Xylocopa comes from the Greek word xylokopos which means ‘wood-cutter,’ a reference to the nesting behavior of these species. The Valley Carpenter Bee is named after the California Central Valley where it is found.

Carpenter Bees have some pretty fascinating behaviors. Generally, they are solitary bees. The females make their nests by boring holes in wood, usually the undersides of branches or beams. They carve their nests by rasping their mandibles against the surface of the wood and vibrating their wings. The holes they bore are not very deep, and so structural damage in not really a concern. However, they are not strictly solitary. Mothers and daughters, or sisters, will sometimes share the same nest. Sometimes they will even divide labor by having one female primarily guard the nest and the other primarily searching for food. Even unrelated females are often quite gregarious, and will often be found nesting in the same general area.

The males generally adopt one of two mating behaviors, and it is easy to tell which species use which strategy by the size of their eyes. Males of some species have very small eyes. These males release large amounts of pheromones that the females use to locate the male. The males of other species have very large eyes. These males search for nest holes of females, and hover outside them waiting for the females to fly by as they are coming or going, and then follow them and try to mate. The male Valley Carpenter Bees that I have been seeing have very large green eyes, so they must use the search and follow strategy.

As with so many other bee species, Valley Carpenter Bees pollinate many flowers, but sometimes they get a bit greedy. If they find a flower that is too deep for them to reach the nectar from the inside of the flower, and so pollinate it in the process, they sometimes use their strong mandibles to slit the side of the flower near the base of the petals and steal the nectar!

If you get to see a Valley Carpenter Bee, they may approach you. Don’t be alarmed. These bees often approach other animals, but both sexes are very docile and the males don’t have stingers at all. So enjoy the visit with these magnificent creatures!

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On Saturday, I co-led the youth bird-a-thon team organized by Point Blue Conservation Science, the Drake’s Beach Sanderlings.  We had a fun and hard day in the field.  Fun because we did manage to see some great birds ending with a total of 145 species.  Hard because the federal government shutdown, that is still in effect in the USA even as I write this, meant that all the national parks were closed.  National parks make up about half of the really good birding sites we usually visit on this bird-a-thon, so we really worked for the 145 total.

While birding, we saw something else that was pretty spectacular.  We got lucky, and happened to be out during a major California Oak Moth (Phryganidia californica) emergence.  It was spectacular!  Thousands of moths fluttering under and around the oaks.  Veritable blizzards of moths scattered across much of eastern Marin County.  At some places, this moth bonanza had attracted birds to the feast.  Yellow-rumped Warblers, in particular, were flocking to the same oak trees to catch and eat the moths.  This was only at some points, however, and it was interesting to note that the peak of the moth emergence was in the afternoon when bird activity was at its lowest.  Coincidence?  I am guessing, no.

California Oak Moths have two generations per year.  The adults are rather plain looking dusky grey or tan with a wingspan of about 3cm.  The adults only live for a short time,and do not eat.  Instead, the males do nothing but find a mate, and the females do nothing but find a mate and lay eggs on the oaks.  The caterpillars are black with a yellow stripe running down the center of the back.  These eat the leaves of several species of oak tree, and can be a significant pest.  In places where the population gets really large, whole oak trees can be defoliated by the caterpillars.  Healthy oaks generally recover, so these moths are not a major threat to the trees, but the effects can still be pretty dramatic.  The pupae are perhaps the most striking in appearance of all the life stages.  They are white, or sometimes yellow, with dramatic and complex patterns of black striping and spotting.  We were fortunate enough to see all three life stages on Saturday!  , and

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This past weekend, my wife and I joined the rest of the graduate group that I am in for our annual retreat.  The retreat was a camping trip to Boca Spring campground.  It is a great campground in the eastern Sierra Nevada between Truckee and the Nevada State boarder at about 5900 ft in elevation, and set amongst Ponderosa Pines and the occasional Lodgepole Pine.  Each morning I got up early and went out to do some birding!  On Saturday morning, I walked along forest service roads through the pines and around the edges of wet mountain meadows amidst the sagebrush.  It was simply lovely.  And there was some great birding to be had!  At one point, I heard a Northern Pygmy Owl tooting away not far from me, though I was never able to actually see it.  On a small ridge line, I found a mixed flick that included Mountain Chickadee, Yellow-rumped Warbler, White-breasted Nuthatch, Red-breasted Nuthatch, and Pygmy Nuthatch.  From what I can remember, this is only the second or third time I have had a three nuthatch species day!  I was quite thrilled!  This flock was moving through the forest along the ridge.  What really struck me was how unevenly the birds were scattered across the forest.  I had found this fair sized flock of birds all in one place, but before and after, walked through forest that looked the same to me and had the same topography, but had no such flocks.  What made that particular small ridge-line so much better than the one to the east or west of it?  On my way back to camp, I got an additional thrill when I heard, and then saw, Evening Grosbeaks in the area!  Back in the campground, there were White-headed Woodpeckers and a small flock of Western Bluebirds.  Also back in camp, a group of Evening Grosbeaks flew right into the trees above us.  There were about eight birds and all the flight calls that I heard were Type 2, which is the dominant Sierra type.
In the afternoon, we visited the Sagehen Creek Reserve.  This is one of the nature reserves run by the University of California.  We were joined by my advisor who gave us a introductory presentation on the birds and habitat of the high Sierra, and then we all went for a walk to see what we could see.  I added Red Crossbill, Pine Siskin, Hairy Woodpecker, and MacGillivray’s Warbler.  We also found an adult Caddisfly.  Not sure of what species, but I am sure that is this first adult caddisfly I have ever seen!  We also found a Comma which is a species of butterfly.

This was a great trip with great birds and other wildlife, and I even got some scouting done for my own research!  I will definitely be returning to the Boca Spring Campground in the future to find my Evening Grosbeaks.

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Today there were lots of Ladybird Beetle larva roaming around on the leaves of several of the bushes in my neighborhood.  They must have been hatching just recently, because I have not been seeing any at all before today.  The Ladybird Beetle (commonly called a ladybug, even though it is not a true bug) is a member of the family Coccinellidae.  This is a family with over 5000 specie world wide, and some members found on every continent except Antarctica (North America has about 450 native species).  The larva have somewhat spiky bodies that are black with red markings on the sides.  They metamorphose into the familiar adult beetles that have brick red backs with black spots.  Interestingly, the adults of many species are plain green when they first emerge, and the red and black coloration develops as the exoskeleton dries and hardens.  A bit of insect trivia for you.

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