2019 Painted Lady Migration in Utah

2019 Painted Lady Migration in Utah

Ideal winter precipitation and other factors have triggered a massive northward migration of the painted lady butterfly (Vanessa cardui) into Utah and other western U.S. states from Mexico.   Previous painted lady mass migrations in the Western U.S. have been noted in 1972 and 1991.

About half the size of the monarch, these fast flying butterflies are everywhere throughout the state where they occasionally take a short break from their northward flight to nectar on dandelions and other flowers.  They also lay eggs on weeds such as cheeseweed in our yards and anywhere else weeds grow.  (Ironically, you may see fewer painted ladies if you have an immaculate garden, free of weeds.)   Because their caterpillars feed mainly on weeds such as cheeseweed, thistles, sunflowers, fiddleneck, and others, painted lady caterpillars pose no threat to agricultural crops.   

Of the tens of thousands of painted ladies passing through Utah's West Desert last Saturday, April 28, 2019, it was interesting to note that some were smaller, worn migrants from Mexico, whereas others were larger, fresher adults representing the next generation that have joined in the migration.

Similar to the monarch migration, the painted lady migration is an annual event that usually goes unnoticed by the public as numbers are substantially less than this year's extraordinary explosion. In fact, in some years, the painted lady northward migration has been so minuscule that, while doing field work, I have failed to see a single butterfly or caterpillar on its many host plants in during its most visible months of April and May.

Painted lady adult butterflies that fed locally on weeds and emerge as butterflies around late May into June continue their trek northward.   During the painted lady mass migration of 1991, well after the offspring of migrant painted ladies emerged, painted lady adult butterflies were difficult to locate in Northern Utah in June/July. This differs from monarchs where migratory monarchs will fly through Utah, lay eggs on milkweed, and continue northward.  However, about one month later, the offspring of those migratory monarchs generally remain local to breed and build their numbers with an additional generation or two leading up to their return migration to California starting around mid-September. (Eastern monarchs migrate to Michoacan, Mexico whereas western monarchs migrate to California.)

The painted ladies' ability to rebound from extremely low to unprecedented high numbers is truly extraordinary even by insect standards.  In order to survive extremely high mortality, most butterflies instinct towards self-conservation is evidenced by laying 300 or more eggs where roughly 97 percent perish due to predation, parasitism, drought, floods, fire, and many other natural factors.

Butterfly predators such as spiders, earwigs, wasps, and others help keep butterfly numbers in check.  However, on occasion, butterfly numbers have been known to temporarily explode based upon a combination of factors including, but not limited to, high winter precipitation in Mexico.  Several years' ago the pine white butterfly (Neophasia menapia) experienced a temporary population explosion and denuded thousands of pine trees in Malheur National Forest in Oregon.  Numbers have since returned to normal levels and the trees have recovered.

This is an unprecedented year for educators and school teachers to discuss the painted lady butterfly and their migratory story during their insect units where it is not difficult to find painted lady eggs and caterpillars between now roughly through the end of May anywhere in the state where weeds grow.

Basic instructions on how to raise painted ladies can be found on my raising butterflies' page here. Social media community observations on the painted lady migration (and other Utah butterflies) can be found by joining the Utah Butterfly Field Trips Facebook page.   Information on Northern Utah Monarch conservation can be found on Monarchs of the Wasatch Front and Monarchs of Bridgerland Facebook pages.  

For more information about this article, please contact Todd Stout at todd@raisingbutterflies.org 

Why not Raise Red-Spotted Purples?

With so much attention placed on monarchs and painted ladies, I sometimes wonder why more folks from the Midwest and Eastern United States (or extreme SE Canada) do not consider raising red-spotted purples as well.  Not only are red-spotted purples (Limenitis astyanax astyanax) one of the more gorgeous butterflies from your area, but also, once you get the hang of rearing them, you've learned 90 percent of what it takes to find and raise viceroys as well. 

The first step to rear red-spotted purples is finding their habitat; which, many of you already know as  openings in wooded areas, gas or powerline right-of-ways, parks, forest edges, forest trails, mountain canyons, etc.

Their larval host plant is wild cherry (Prunus serotina).  Usually, the best time of year to find eggs and larvae of the red-spotted purple is during their last generation in late August and September when their numbers are usually are at their peak.  Females lay their eggs on the tips of wild cherry leaves and young larvae make conspicuous perches that you can train your eye to locate.  More.  (Also, another tip is to find eggs and larvae on isolated cherry trees within the heart of a population.)

Taking care of eggs and caterpillars of the red-spotted purple only requires that you place wild cherry cuttings in water and place in a bucket or semi-closed terrarium.  Replace cuttings and remove frass about every five days and keep second and third instar caterpillars under 24 hours of light a day; so that larvae avoid hibernation.

Also, for those of you more adventurous types, you can also collect live red-spotted purple females, cage them, and obtain dozens of eggs.  Click here for more information.  (If you live in Western North America, click here for strategies on rearing weidemeyer's admirals; here for Arizona purples; here for lorquin's admirals; or here for white admirals (ssp. rubrofasciata.) 

So, if you live in the Midwest or Eastern U.S. and enjoy treks into the woods during the late summer months, why not examine the tips of a few wild cherry leaves to see what you will find? 

To learn more about rearing red-spotted purples, please visit http://www.raisingbutterflies.org/red-spotted-purple/ or email me if you have any questions.

Six Steps to Keep Caterpillars Healthy and Free from Disease

Caterpillars of certain butterfly species are easier to raise than others.  In addition to OE that can infect monarch caterpillars, other butterfly caterpillars can get sick and die from viruses or bacteria as a result of many factors.  The following helpful hints can help you maintain a safe environment for raising butterfly caterpillars through to healthy adult butterflies.

1. Raise caterpillars in manageable quantities.  Unless you are an experienced butterfly rearer or breeder, rearing caterpillars in mass quantities greatly increases the chance for larval disease.  
2. Remove caterpillar frass regularly.  Whether rearing caterpillars in an open terrarium, it is always advisable to create a regular regimen of removing caterpillar frass as regularly as possible.  The longer caterpillars are exposed to their own frass, the more likely caterpillars can get sick.
3. Keep Rearing Environment Free from Humidity.  Pathogens can multiply exponentially and easily infect caterpillars if caterpillar frass is allowed to remain moist.  With the exception of admirals or viceroys, raise caterpillars in an environment with plenty of airflow; allowing frass to dry naturally.
4. Raise caterpillars on potted plants as opposed to cuttings when possible.   Raising caterpillars on potted plants has advantages over cuttings because of the nutritional value of live plants.  If you do use host plant cuttings, replace regularly, depending upon the species of butterfly and variety of host plant.  Do NOT allow cuttings to deteriorate or rot.  More.
5. Disinfect your rearing environment regularly.  When dealing with the disinfection of viruses or bacteria, using a two chain quaternary ammonium compound aerosol (like Lysol) is the easiest method to disinfect 99.9 percent of viruses and bacteria.  Apply aerosol directly on non-porous containers and cages for 30 seconds and remove with clean paper towel.  Using bleach (Sodium hypochlorite) also is effective; but can be more labor intensive for some.  Chemical disinfectants are used for preventative measures and cannot heal caterpillars once they are infected.
6. Understand which butterfly taxonomic groups are more susceptible to disease and require more attention:  Some species, species groups, or genera require more attention than others.  Use the following matrix as a general guideline:

Taxonomic Group:	Disease Susceptibility:	Special Concerns:
Nymphalidae:  Nymphalinae and Melitaeinae (brushfoot butterflies including anglewings, tortoiseshells, ladies, buckeyes, checkerspots, and crescent spots.)	Low	Use open terrarium technique. Disinfect, replace cuttings, and remove frass every five days.
Nymphalidae:  Danainae (monarchs and queens) and Heliconiinae (longwings)	Medium	Disinfect for OE; remove frass and replace cuttings every three or four days.
Nymphalidae: Limenitidinae (admirals and viceroys)	Low	Larvae are less susceptible to disease when rearing in a humid environment as they are accustomed to this in nature.
Nymphalidae: Satyrinae (wood nymphs and ringlets only )	Low	Larvae are generalists and avoid disease if reared in potted grasses of many common varieties
Nymphalidae:  Greater Fritillaries from the genus, Speyeria.	High	Special needs group.  See instructions located here.
Pieridae and Lycaenidae (white/sulphurs/orange tips and blues/coppers/hairstreaks)	Medium/High	Avoid closed container rearing whenever possible. Larvae are very susceptible to illness when overexposed to their own moist frass; even if reared in isolation.
Papilionidae (Tiger and machaon group swallowtails)	Medium	Avoid closed container rearing whenever possible.  Avoid humidity; especially for Western North American species.
Papilionidae:  Papilio indra complex	High	Special needs group.  See instructions located here.

This matrix is a general summary and is not all-inclusive.  For more information about species-specific rearing strategies, please see http://www.raisingbutterflies.org/raising_butterflies_301/ or email me.

Five Simple Steps to Obtain Butterfly Eggs and Caterpillars

One of the simplest ways to obtain butterfly eggs is to collect female butterflies and set them up in a cage to get eggs so that the eggs hatch into caterpillars which later become butterflies.  This can be accomplished by following these basic five steps.

1.  Take a reliable butterfly net and find the variety of butterfly you're looking for in its natural habitat. More.
2.  Learn to separate male butterflies from female butterflies.  More.
3.  Collect a live female butterfly and feed feed her regularly to keep her alive.  More.
4.  Place your female butterfly in a small plastic tub, nylon sleeve, or butterfly cage depending on the variety of butterfly.  More.
5.  Properly care for your eggs before they hatch into caterpillars.  More.

For more information on how to care for butterfly eggs, caterpillars, and the inexpensive equipment needed to rear them through to adult butterfly, please visit us at http://www.raisingbutterflies.org/techniques-for-caring-for-imma/ or please email me at todd_stout29@hotmail.com for specific help.

Raising Giant Swallowtails

Giant swallowtails can be very common in the southern United States from California east to Florida where they feed on new growth of citrus trees. It's really important to remember that if you find a citrus tree, always try to find ligher-colored leaves that leafed out recently. These are the leaves female giant swallowtails prefer to lay their eggs.

In other words, don't be intimidated at a large citrus tree when looking for giant swallowtail eggs and caterpillars. Simply focus on new growth; whether found on the tips of branchs or suckers coming out of the trunk.

For more information, please see http://www.raisingbutterflies.org/giant-swallowtail/