Arquivos de periódicos de junho 2018

10 de junho de 2018

On a spruce stump

About five years ago, an old spruce tree fell down in our yard. Luckily it didn't hit a pedestrian, fall toward the house, or smash a car on the street. It cost a bit to remove, but at least it didn't hurt anyone or anything.

We decided to take out another old spruce at the same time, leaving an eight-foot stump for whatever wildlife might find it useful. I didn't notice much in the first few years, but starting this spring the stump is the most active place in my yard, at least as far as insects are concerned.

The first to show up was a mason bee (Osmia) on April 22. A few days later, I drilled a some holes in the stump, hoping that some bees would use them as nests. And by April 26, some of the holes were already being used by bees.

Here's a list of other visitors to the stump that I've seen so far this spring and the date of first sighting:

April 26: Temnoscheila
A bark-gnawing beetle (Trogossitidae)
These colorful beetles apparently eat the larvae of other beetles. (And, at least on my stump, invade Osmia nests.)
Myrmecos - Friday Beetle Blogging: Temnoscheila Bark-Gnawing Beetle

April 26: Western Carpenter Ant (Camponotus modoc)
I'm not sure of the ID on this, since my observation hasn't yet been confirmed on iNat.
These large ants often hang out on the stump, occasionally entering holes that are occupied bee nests

April 27: Club-horned wasps (Sapygidae)
These wasps land next to an occupied hole and wait until the mother bee leaves to get more pollen. Then the sapygid wasp enters the hole and deposits her eggs. When her eggs hatch, the larvae feed on either the pollen that the bee provided for her larvae or the bee larvae themselves (or both).
(I've often seen them enter the holes, but I couldn't, of course, see what they do when they get inside.)
Here's a post by Bug Eric on them: More Drama at the Bee Block

May 1: Xorides (Ichneumonidae)
These wasps have been present nearly every day for the last six weeks. Often there are two females on the stump at the same time, and occasionally males are present as well. The females slowly move around on the stump while tapping their antennae on the surface of the trunk. Apparently this is the way that they detect beetle larvae in the wood. I've seen females ovipositing, and once observed the entire process, which took about 90 minutes.

May 3: Orussus
Parasitic Wood Wasps (Orussidae)
Females flit about on the spruce stump, stopping occasionally to deposit eggs. It takes a few minutes, during which time it is easy to get up-close pictures. While they search for a place to oviposit, they tap their antennae tips on the stump in much the same way as the Xorides wasps.
(The ovipositor is up to twice as long as her body and is coiled internally in the thoracic and abdominal cavities. - Bug Eric's post)
On May 20, a male showed up and interacted with a female, flicking the tip of his abdomen as they did a little dance while circling around each other. The male of this species (which I suspect is occidentalis) has a black abdomen, while the female's abdomen is red.
I have videos of the female ovipositing and the male/female dance, which I'll post if I ever can figure out how.
Bug Eric - Wasp Wednesday: Orussid Wasps
Olympic Natural History: Parasitic Wood Wasps - Orussus sp.

May 15: Chrysura
Cuckoo Wasps (Chrysididae)
These beautiful little wasps also parasitize Magachilid bees, especially Osmia. They're hard to photograph, though, since they are small and move around fast. The adults have thick armor on their head and thorax to defend against stings from angry mother bees. They also have the ability to roll up into a ball like a pill bug when being attacked. The larvae are also tough little guys, who don't bother with the nectar and pollen provided for the bee larvae; they eat the bee larvae themselves (after eating any siblings that might have hatched from the eggs deposited by the mother wasp).

May 16: Osmia lignaria propinqua
Blue Orchard Bee (Mgachilidae)
There were other mason bees nesting in the holes in the stump, but so far I've been unable to identify them.

May 20: Zebra Jumper (Salticus scenicus)

May 25: Western Eyed Click Beetle (Alaus melanops)
Larvae are predators of wood-boring beetles
Bug Eric: Eyed Elaters

May 25: Goldenrod Crab Spider (Misumena vatia)

June 11: Potter wasp (Subfamily Eumeninae)
Saw one enter hole in stump. Several others also observed in the vicinity.

June 15 Gasteruption
Small (~13 mm) wasp was patrolling the stump this afternoon. Caught it in tube, cooled, photographed and released.

June 19 Bald-faced Hornet (Dolichovespula maculata)

Posted on 10 de junho de 2018, 06:40 PM by swells swells | 13 observações | 2 comentários | Deixar um comentário

19 de junho de 2018

On a spruce log

As I mentioned in the previous post, we left a stump standing when removing spruce trees after one fell in our backyard about five years ago. The stump has since become a very active place, with lots of bees, wasps, ants, beetles, and other insects making their homes there. At that time, being a bit lazy, I also left some spruce trunks and branches in a brush pile, rather than disposing of all of the debris. And that brush pile has since also become a great place for watching and photographing insects.

I first noticed small wasps (10 -12 mm) flitting about on the larger branches of the brush pile a couple of summers ago. They seemed to be nesting in the log, since I noticed some holes with what appeared to be sawdust piled beneath them. I managed to get a couple poor photos that I posted on iNat, which were subsequently identified by John Ascher as aphid wasps in the genus Pemphredon.

Well, they are back again this year. And I now that I know what they are, I'm able to spend some time observing them -- rather than just trying to get a picture to identify them. Previously when I saw them they were hard to observe or photograph, since they were constantly flying around and never seemed to sit still for more than a second or two. But yesterday they were much more cooperative.

There was one in particular that stood next to a hole in the log. It stood there nearly motionless for several hours -- at least it was there every time I came out to check on it. A couple times when I was watching, another Pemphredon would poke its head out of the hole, at which time the guy (I'm thinking it's a male) appeared to get all excited, tapping his antennae and moving about near the hole. The other wasp would generally go back into the tunnel and then completely emerge a few minutes later. As soon as the wasp left the hole, the waiting wasp would pounce on it for a split second, before the other wasp flew away. I don't think any mating occurred the two times that I observed this behavior. Perhaps the other wasps were males, rather than a female that waiting wasp was waiting for. I never saw a mating event, but I'll keep checking and maybe I (and the waiting male) will get lucky on another day. (It was rainy today so there was no activity.)

While watching the aphid wasps, I noticed some other small ichneumonid wasps (~ 13 mm) flying around the the spruce log. I managed to get a few pictures of them, which I posted to iNat. BugGuide identified them as Perithous scurra subspecies neomexicanus, saying, "The host is an aphid wasp in the genus Pemphredon.

So these little ichneumons are hanging out around the spruce log trying to parasitize the aphids wasp nests! Tomorrow I'll be hanging out there as well, if the weather improves a bit.

Posted on 19 de junho de 2018, 04:44 AM by swells swells | 2 observações | 0 comentários | Deixar um comentário