Rearing butterflies from eggs or larvae can be satisfying and fulfilling, or it can be frustrating and disappointing. There are ‘eureka’ moments when a bright light heralds a sudden new discovery, and there are crushing moments when larvae you obtained from a difficult long trip all decide to stop feeding and die for no apparent reason. There are exciting new discoveries of unknown food plants, and there are sad dissapointments when your larvae grow to the very point of pupation and then inexplicably languish and die.
For many of our Washington butterflies there is little literature or other resources to help a person find or rear larvae. To be successful in rearing it is important to become familiar with native plants, and one must pay close attention to seasons, weather, elevation, timing and proper habitat. It is also very important to be able to identify female butterflies from males; while I have tried several times to obtain eggs from males, this is usually quite unproductive! Studying the limited literature will help provide other critical clues such as adult flight periods, overwinter stage, foodplants, and if you are lucky maybe some tips for larval identification or other information. It’s an exciting big nature treasure hunt, with clues provided here and there in isolated fragments, and with lots of large knowledge gaps which you will need to fill in for yourself. When those clues finally come together, and you find a larva you are specifically searching for, and just where and when you predicted you would find it, you can experience the exciting rush of scientific discovery for yourself.
I surprised myself recently; in looking at some of my earliest photographs of larvae I discovered that I have been studying these fascinating creatures for ten years now, much longer than I had thought. And even after ten years I definitely do not consider myself an expert. As many of you know I have been working toward a book on Washington butterfly larvae, and to my great relief I have found a lepidopterist of like mind in Dr. David James. We have joined forces now, and the task of documenting most of our local butterflies seems less a dream and more a matter of timing now. It will be a nearly impossible task to document all of the stages of all our Washington butterflies, so we expect the book will be a starting point, one to which others can add their discoveries later.
I am often asked which butterflies are the most suitable for rearing in the classroom. This is a surprisingly difficult question, simply because most northwest butterflies are summer creatures, and most school classes are out of session during the summer. A number of species can be reared in classrooms, but some will be difficult to obtain, others need foodplants which are not easily available, and most will not hatch to adult butterflies before classes are recessed for the summer. In short we are left with a few “old standbys” like the Painted Lady, which is available commercially together with artificial food, and of course Monarchs similarly available, and maybe the rather unattractive non-native Cabbage White. And of course most children want to release their butterflies into the wild, which may cause problems to scientists who are trying to study these species in the wild. So should classes avoid rearing? No, certainly not; rearing provides a great learning experience for children. But the best opportunities for kids will be to rear their own ‘livestock’ at home during the summer, perhaps with the help of their parents.
Another question I am often asked is which species are the most difficult to rear. The first inclination is to answer that, of course, the rarest butterflies are the most difficult. But this is not necessarily correct. Rare butterflies are difficult to *obtain*, but not necessarily difficult to rear. Actually, some of the most difficult to rear are often common species. Take the buckwheat blues for example, the “Square-spotted” and “Dotted” Blues in the genus Euphilotes. These common butterflies are very small, so their eggs and larvae are tiny and difficult to handle. The larvae feed only on the fresh flowers of buckwheat plants, and once cut these flowers have a very short shelf life; and if you happen to live in western Washington you are unlikely to have suitable buckwheats growing nearby. If you should be successful in growing buckwheats they will probably bloom at the wrong time of year for the eastern Washington larvae you gather. And for a final blow, if you are successful in obtaining eggs you will find that the tiny newly hatched larvae immediately bore into the flowers where they are easily lost. When those (cut) flowers wilt and decompose a day or two later the larvae die unseen. These problems make for a very difficult set of rearing conditions.
Another very difficult type of butterfly to rear is one which takes multiple years to develop. All three of our Arctics, in the genus Oeneis, take two years to develop. So it is necessary to overwinter these larvae twice, once as a small larva the first year and again the next winter as a nearly mature larva. In the meantime, the larvae grow with excruciating slowness, and must be supplied with fresh grass foodplants through two entire summers. Just one miscalculation over that two year period, perhaps allowing a direct sunbeam to ‘cook’ the larvae, or allowing mold to grow during the winter, or failing to keep the larvae moist to avoid desication, and you will have the privilege of starting all over. And as the adults fly only on alternate years you may have to wait a full year before you can even try again. Such larvae are understandably very difficult to rear to pupation, and as a result you will not find many published photos of them. And typically Oeneis larvae are exceedingly difficult to find in nature as well, so it is not practical to shorten the process by finding partially grown larvae.
So how would I suggest a person plan a successful larvae- finding trip? Well the first rule would be to go where butterflies are abundant, probably an area you are already familiar with. But before going you will want to ask yourself which species you have seen there in the past, especially which species are the most abundant there. So now you may be starting to form a general idea of your target species. The next step would be to do some research on your target species. When are the larvae likely to be present? The adult flight period and the overwinter stage should provide strong clues for you. In midsummer butterfly species you will typically find late instar larvae around 3-4 weeks before the adult flight period starts. But be aware that larvae are best found before the flight period in some species (including those which overwinter as eggs), but after the flight period in others (such as those which overwinter in the chrysalis). Think about the life cycle, and draw your own conclusions about when the larvae are likely to be present. Next ask what is the larval food plant, and what part of the plant is eaten? Don’t be afraid to ask for help; or consult a local book such as Butterflies of Cascadia for information. Be sure that you can identify the food plant in the field. And you might want to check with someone to assure that you are not attempting a particularly difficult species; for instance Speyeria (Fritillary) larvae are nocturnal and are very difficult to find. You might want to start with an easier target, and you might want to ask for suggestions on just what to look for (holes in leaves, silked nests, frass), and for other clues for a good search pattern. When you feel reasonably comfortable that you are going to a good place at the right time, the next thing to do is tell yourself that the larvae are there and that you can find them. Confidence is very important. And finally just go and search. Be prepared to be patient, concentrate on the target species, bring all your powers of observation into focus, and try to avoid distractions. You can and will find what you are looking for, but it may not be easy. But above all relax and enjoy your day in the field. After all, that’s what it’s all about.
All Photos by Dave Nunnallee
G’num2006Vol7No2
Dave Nunnallee
WBA Cofounder and Former Board Member, Coauthor of Life Histories of Cascadia Butterflies
