12 Summer 2017 Applegater population. They hibernate, reproduce, The California Tortoiseshell and live here throughout the summer. In fall they will overwinter here again in flight this summer with some emigrating south to live. There is still much to learn about BY LINDA KAPPEN the reasons for the large irruptions of the California Tortoiseshell. One As with most species, reason may be the health and optimal the male perches looking conditions for specific predators of the for females. The females butterfly, e.g., a parasitic wasp. Thus a will lay their eggs in good year for parasitic survival results bunches on the host in lower numbers for the butterfly, and plants. As the young Tortoiseshell underside vice versa. caterpillar grows, it The last large population irruption feeds on the leaves in a of this butterfly that I witnessed locally close group with other They can be seen in flight from January to was around 2001, when hundreds of caterpillars. November. April through August are peak California Tortoiseshells flew around Adults overwinter months for this butterfly. Applegate School and were seen in large and will fly early in the Host plants are species of groups puddling on the track, which is day, coming out on (wild lilac). Breeding occurs in the decomposed granite. There may have California Tortoiseshell butterfly warm days through late Ceanothus zones of the mountains. been a smaller irruption in 2009 in our winter and spring. In This butterfly lives in lower elevations mountains, including the Cascades. After The California Tortoiseshell ( mid-spring, the Tortoiseshells mate and in clearings and at edges of forests and witnessing an irruption, folks sometimes californica) is of the family of lay eggs for another brood. In southern in woodlands, canyons, river corridors, mistake the for migrating butterflies. It is dark brown with a reddish- Oregon, these butterflies may have up to and brushy areas. They have a wide range Monarchs, only to find out they are indeed orange tinge and big and small black spots two or three broods some years. on the western side of the Rockies from California Tortoiseshells. It would be on the middle of the upper side. A dark The overwintering adults feed on fir- British Columbia, on the Pacific Coast, to awesome to witness another irruption of brown to greyish pattern, which resembles needle exudate in early spring. Exudate is Baja, and east to Colorado, New Mexico, this beautiful ! a dead leaf or tree bark, appears on the a substance excreted by fir needles. Adults Montana, and Wyoming. Linda Kappen underside of the wings. The butterfly’s will later use nectar for food and visit The California Tortoiseshell is known [email protected] wingspread can be up to 2.5 inches. mud puddles or damp spots in roadways. to have irruptions or “outbursts” in Butterfly photos by Linda Kappen.

Notes from a Rogue entomologist the western US and is fair- sized (between a quarter- inch and a half-inch long). on milkweed— Occasionally you can find quite large populations feeding on milkweeds, and more than just monarchs when that happens they are hard to miss. BY RICHARD J. HILTON Both the cobalt Monarch butterflies are always a commonly seen. The oleander plant is beetle and the monarch welcome sight, and finding caterpillars in the same botanic family as milkweed have evolved the same with their bright yellow and black bands and also produces some similar toxins. physiological mechanism feeding on a milkweed plant is inevitably a The oleander aphid is bright yellow with for dealing with the toxin delight. Add in a chrysalis that is adorned dark legs, feeds on the plant sap with a produced by the milkweed with gold trim and it is easy to see why sucking mouthpart, and can reproduce plant. Additionally, the such a spectacular species is the focus of rapidly. You often find milkweed plants adult cobalt beetle and the so much attention. whose pods are completely covered with final stage of the monarch The fact that monarch butterflies engage these small insects. Gardeners growing caterpillar have also developed in an annual migration covering thousands milkweed often consider these aphids a an interesting adaptive of miles is remarkable. Unfortunately, pest and unwanted competition for the behavior whereby the insect the overwintering sites in Mexico for the desired monarchs. Look for articles on the cuts the stem or mid-vein of population of monarchs that migrate web, like the one titled “10 Good Ideas the leaf prior to feeding on it. into the Eastern and Great Plains states for Keeping Milkweed Aphid-free…and 1 This reduces the sap flow and have been under threat, and while they Bad One” at monarchbutterflygarden.net/ lessens the amount of toxins are now largely protected, climate change control-aphids-milkweed-plants. moving into the leaf that is and habitat destruction loom as very real Another milkweed-sucking insect is the being consumed. concerns for this charismatic species. small milkweed bug, which is extremely The monarch butterfly is Our western monarchs overwinter common in our region. (There is also a one of our most recognizable in California and while the threat there large milkweed bug that has distinct red insect species, but this summer is not as severe, the western population coloration and, while it is reported to be when you see a milkweed has declined over the last 20 years. In in Oregon, I have never observed it here in plant, please keep an eye out response to the reduced numbers of the Rogue Valley.) The small milkweed bug for some of the lesser-known monarchs, there has been a nationwide is often confused with the boxelder bug as insect inhabitants that can effort to plant milkweed and monarch they are both “true bugs” and have a similar survive on this poisonous host. waystations to encourage them in their size and shape. In addition, both insects One of the pleasures migration. Milkweed plants contain toxic have some orange to red coloration. You of studying insects is their chemicals that the monarch sequesters and can tell the difference—the small milkweed immense diversity, and the uses to deter predators, accounting for its bug’s markings are more pronounced, group of insect species that dramatic coloration that acts as a warning making an X shape on the insect’s back, can thrive on milkweed plants sign to potential predators. and the small milkweed bug can also have is no exception. However, monarchs are not the only two white spots towards the rear end. Richard J. Hilton insects that can live on milkweed and The last of my trio of local milkweed 541-772-5165 ext. 227 survive the toxins produced by the plant. insects other than monarchs does not Senior Faculty Research Locally, there are three insect species have any yellow, orange, or red warning Assistant / Entomologist other than monarchs that you will often coloration, but it is, to my mind, the Oregon State University- Top photo: Oleander aphids (wildernesscenter.org). find when you are out searching milkweed most striking of the bunch. It is popularly Southern Oregon Research Middle photo: Small milkweed bug plants for monarch caterpillars. The known as the cobalt (or blue) milkweed and Extension Center (commons.wikimedia.org). oleander aphid is probably the most beetle. This metallic-blue beetle is found in [email protected] Bottom photo: Cobalt milkweed beetle (thoughtco.com).