Wednesday, October 27, 2010

Monarchs in the Phoenix area in late October

They're everywhere! Two weeks ago I wondered where the monarch butterflies were - then the floodgates opened. Finally in October day-time temperatures cooled and monarch sightings surged around the Phoenix area. Monarchs are continuing to visit milkweed thickets and nectar sights around town even as we approach the final week of October.

Even more interesting is the late surge of monarch egg-laying. I know of over 20 nearby larvae or pupae (so there are likely far more), most on Desert Milkweed, Asclepias subulata. Usually we see this activity in September. While a few females were laying eggs then, I haven't heard of any successful offspring. Our record high of 111 likely squashed a successful generation. But now in October we still see monarchs laying eggs with caterpillars and chrysalids around town. A fresh and new looking female laid eggs just two days ago in my yard.

While the monarch breeding activity is continuing in the Phoenix area, migrating monarchs are beginning to reach their overwintering grounds in Mexico and California. Journey North posted a news flash announcing the first arrivals in Mexico. Citizen-scientists and casual observers are reporting monarchs along the California coast. Robert Pacelli gave his permission to share this photo of monarchs gathering yesterday at Pacific Grove. Robert spearheaded an effort to create a restoration habitat after massive pruning crashed the number of overwintering monarchs last year. Early indications are very hopeful with monarchs once again returning in higher numbers. Efforts to save the monarchs make a difference.

Locally, monarch butterflies are beginning to return to a small sanctuary at the Rio Salado Restoration Habitat. Last Saturday and again yesterday we spotted monarchs nectaring on Desert Milkweed, Asclepias subulata, and resting in nearby trees. Monarchs that leave too late to reach the coast of California or Mexico have found a protective haven in this small oasis in the desert the last several years.

With all the local monarch excitement we don't want to lose the wonderful experience Bob and I had in Eagle Pass, Texas. Leslie Gilson, Bob and I joined Carol Cullar, Mary Kennedy monitoring the Eastern monarchs as they moved through Southern Texas into Mexico. We'll post more photos later, but just had to show a small glimpse into a monarch roost of 5,000 in Del Rio, north of the area.

Wednesday, October 6, 2010

Phoenix Area Monarch Migration

A year ago monarch butterflies were everywhere. Here we are in the middle of the peak time of the annual Fall monarch migration in the Phoenix area - where are they? Queen butterflies (see photo on right) are abundant, but what about their annual family reunion with the monarchs as they pass through Arizona on their way to the coast of California or Mexico?

The first sighting of monarch butterflies was earlier than last year, but the number of monarchs has been lower. The scorching heat of September has likely put a lid on monarch activity around town as well as reproduction. September was the second hottest on record for the Phoenix area and monarchs don't like the heat. Instead of seeing monarchs flourish on milkweed patches, we are finding them hidden, nestled in willow or cottonwood trees near water where temperatures are cooler. We were hopeful that once the heat finally eased on Monday more monarchs would roll in. Perhaps they would have - if two days of severe thunderstorms hadn't dominated the weather! Lashing winds, pounding rain and marble to baseball size hail whipped monarchs wherever they are. Today is the last day of rain in the forecast and now cooler temperatures will dominate our weather. Last year monarchs were visiting milkweed patches around the Phoenix area by October 1st. Keep an eye out now that our weather finally is more favorable.

The monarch news isn't all bleak. Last Friday and again on Sunday a female monarch visited my yard early in the morning. Tatsuyo on South Mountain also saw one in her milkweed patch. Likely others are seeing similar activity. Ten days earlier Laura in South Scottsdale saw a female monarch laying eggs on Desert Milkweed, Asclepias subulata, in her yard. But the record breaking temperatures of 108 prevented any larva.


Bob and I were thrilled to see the monarch on Sunday morning laying eggs on the Desert Milkweed in our yard. (You can see her abdomen depositing eggs on the flower.) Last year we noticed that monarchs frequently lay eggs on the flowers or very fresh new growth of Desert Milkweed, Asclepias subulata. The tiny caterpillars easily eat the soft, fresh growth. As they get larger, the caterpillars can ingest the thicker branches. Both Tatsuyo and I are watching the eggs, hoping for caterpillars. I have three tiny ones from last Friday's egg laying activity that we hope will successfully grow. Stay tuned!

A question that often pops up is how can we tell the difference between a migrating monarch and a reproducing one? Right now in Arizona we likely have both. Migrating monarchs like each other! They are usually found in clusters and males and females are seen together without mating. Their reproductive urges are on hold - they are similar to a pre-adolescent. Sometimes it is easy to spot a female reproducing monarch by their egg-laying activity. Females usually lay eggs in the morning hours and you can spot them by their scooping-like activity around milkweed plants as they search for just the right place to lay their eggs. Reproducing males frequently set up patrols, gliding over milkweed patches over and over again, hoping a female flies into the area. Another difference between reproducing and migrating monarchs is the size of their abdomen. Migrating monarchs can weigh up to double the amount of reproducing monarchs. They nectar heavily to fuel their long migration. In the field you can often spot the thicker abdomen size. Their heavier weight often makes migrating monarchs slower, so they are easier to net and tag.

Want monarch butterflies to visit your yard? Local plant sales begin this weekend! Boyce Thompson Arboretum in Superior and the Desert Botanical Garden both offer various milkweeds, members of the Asclepias family.