Naturalist's Notebook

Ask the KP Nature Guide: Moles

Q: Why do moles want to be in my lawn? — Tom Herron, Rocky Bay

A: It’s pretty simple. Down below what you mow, a lawn is an expanse of damp and enriched soil. Moles love it because earthworms and other critters love it.

Our most common creator of lawn volcanoes, the Townsend’s mole, is the largest mole species in North America. It has 44 teeth set in a long narrow snout, and beyond earthworms its diet includes slugs, snails, beetles, leatherjacket grubs, centipedes, crickets and pill bugs, all attracted to the oasis of an irrigated lawn.

Moles do their best tunneling — up to 15 feet per hour using their front claws like flippers — when soil is wet and workable. They create two types of tunnels. Winding surface tunnels, 1 to 4 inches deep, are used to find food and scout the terrain. They are often soon abandoned. Runway tunnels, 4 to 20 or more inches deep, are a mole’s highway system and kept in good repair. Moles are solitary animals and only enter each other’s burrow systems during mating season. The nest chamber is lined with a thick thatch of soft leaves and located at a medium depth so that it will not flood. Moles will bring wet vegetation into the nest chamber to provide heat as it decomposes.

Molehills are the excess dirt from a mole’s excavations. Like earthworms, moles aerate soil. They keep other critters in check. And they aggravate lawnmowers to no end.

A Word on Spiders

Now let’s talk spiders. ’Tis the season.

First to level some persistent myths: No, brown recluse spiders are not found in Washington. Their range doesn’t even reach Colorado. Yes, black widow spiders can be found here. And yes, hobo spiders live here too. But no, neither are worthy of the great fear they inspire.

“Spider bite” is the knee-jerk diagnosis for any mysterious bump or lesion that appears on a human body, but professional arachnologists argue that in fact spiders are rarely to blame. Seldom is the “bite” witnessed or the spider recovered. Those who handle spiders often know that they only bite in extreme circumstances — when they are being crushed. The popular idea of spiders roaming at night looking to bite is a bogeyman story.

Black widows have a potent neurotoxic venom. Their bite causes intense pain that can remain localized around the bite or travel throughout the body, wracking the victim. Yet almost all victims recover in 24 to 48 hours without needing antivenin. Black widow venom is not intended for us. We are far larger than its prey. So why does the myth of their deadliness persist? Must the knowledge of possible pain morph, on the shiny back of a black creature, into a fear of death? Anyway, I often see black widow webs around my house and pay them no mind. Black widows are incredibly shy creatures. I simply refrain from jabbing my bare fingers into crevices.

The case of the hobo spider is stranger — and deadly. But only deadly, in the end, for the spider, and for the many other spiders beside that are smashed without reason. A study 30 years ago found that hobo bites cause necrosis in rabbit flesh. Within a decade, it was widely accepted that hobos were right there with widows and recluses, and “hobo spider bite” was a regular diagnosis in the Northwest.

The only problem? There has not been a single case in which an injury can be directly attributed to a hobo spider. Observant doctors and scientists have lately recognized that what evidence has been presented by patients has always been circumstantial. More often, the spiders have been absent. Assumed. And it’s not bad just for the spiders. Jumping to the “spider bite” diagnosis means that the real diagnosis is missed.

While hobos can be found in homes, there are dozens of other house spiders, including the commonly encountered and quite good-natured giant house spider, which looks quite similar. Over 800 species of spiders live in Washington. Except for the female black widow’s red hourglass, their markings are not a great tool for identification. Many spiders look so similar that they can be fully identified only by an expert examining their genitalia under a microscope.

I am not sure I’ll get to that level, but I’d like to continue covering spiders. Send me your photographs and stories. The black hole of fear around black widows and the like can distract us from a whole menagerie of other odd spiders nearby.

Wait and Watch:
Douglas Firs in Drought

A symptom of heat and drought in Douglas firs is the browning and shedding of needles. A healthy tree might have four or five years’ worth of evergreen needles. In the aftermath of June’s extraordinary heat wave, I noted that a number of Douglas firs in my neighborhood had a sere, copper-brown cast. On closer examination, I saw that the second-year and older needles had gone fully brown. This year’s growth tips remained bright green.

Trees do have the ability to redistribute water and sugar for survival, and to cease transpiration when heat will wick them dry. When those systems fail, they can later recover from the die-back of their limbs and leaders. Yet the full damage done by drought does not often appear until the following spring or for several years beyond.

Will there be lasting damage? In which settings? Are there other factors at play? Coming out of a dry summer punctuated by extreme heat, I’ve got my eye on it and I’d encourage you to pay attention as well.