Now the hunt begins!

Now the hunt begins!


By Rick Mikula (May 2018)


By now your Monarch Migration Station should have a good assortment of both host and nectar plants for you summer visitors. The nectar plants will draw in the thirsty females and once there they will surely find host plants and hopefully lay eggs. Closely watch as any butterfly enters your oasis. As it lands on a plant watch for it to curl her abdomen to the underside of the leaf. It only takes a second for it to deposit an egg and then it will quickly move on. Once it leaves the plant carefully turn the leaf up and examine it for an egg. Eggs vary in size and shape according to species and come in a variety of colors and designs. Many butterflies prefer to lay their eggs singly so their caterpillars will not have to compete with their siblings for food some, while other butterflies such as the Mourning Cloak, Hackberry and Checkerspots will lay their eggs in clusters or strings. Eggs that are laid in clusters result in caterpillars that feed in clusters, at least until their later instars when dining with the family any longer may not leave enough food for everyone. So wandering off  is a survival strategy that better the odds for the caterpillar of making it to the chrysalis stage.

Monarch butterfly chrysalis

Mourning Cloak Butterfly

Another problem with having too many brothers and sisters is when a caterpillar goes into chrysalis before the others. At this point it is very venerable and can easily be knock loose from its cremaster or even cannibalized by a siblings. The Anthocharis or Orange Tip butterflies are very notorious for devouring any competition they may encounter.

Female monarch nectaring on Lantana camara

To guarantee that her larvae will find plenty to eat, the Marbled White from the UK drops her eggs randomly as she flies above fields of wild marjoram, thistles, and knapweeds, knowing that her caterpillars will find a waiting buffet once they emerge. Other species are more cautious and will actually lay their eggs away from the host plant to prevent them from being parasite by other insects or accidently eaten by grazing animals. Fritillaries are famous for this and many of them will purposely deposit eggs several feet away from the host plant. The newly emerged caterpillar will then eat what is left of their egg shell and immediately go into hibernation until the following spring. After several months of sleep and the temperatures begin to rise off they go in search of the tender young leaves of violets.


Happy, healthy Monarch caterpillars


Even though a caterpillar looks like a soft mushy pile of squishy stuff they actually have many as 4,000 muscles in its body compared to a humans who only have a measly 629 muscles. And they are eating machines! There are only two things that caterpillars do is eat and pooh! The typical Monarch increases in body mass by 2,000 times in just two weeks. While many caterpillars will look the same throughout the larval stage, many species change their appearance as they mature. Most notably are the swallowtails butterflies and fine example of this process is the Spicebush Swallowtail. In its early instar the larvae looks like bird droppings and does not appear to be very tasty meal at all. With time it will eventually transforms into something that could easily be mistaken as a snake. The largest caterpillars in the U.S. is the Regal or Royal Walnut Moth.  Also called the Hickory Horned Devil is among the largest of our native caterpillars and they can grow to the size of a large hot dog. The smallest caterpillar in the US belongs to the smallest butterfly in the U.S. the tiny Western Pygmy Blue.

Early instar Spicebush swallowtail caterpillars


Later instar Spicebush resemble a waiting snake

Adult Spicebush swallowtail butterfly


But not all caterpillar are friendly. Some species such as the Green Saddleback, Io or Stinging Rose caterpillar have bristly hairs that are attached to venom glands. Others such as The Hickory Tussock Moth sport barbed hairs that will hooked themselves into the skin of an attacker and cause a nasty irritation. The most venomous caterpillar in the US is the furry puss caterpillar . The sting of a puss caterpillar is described as the worse bee sting that you ever got and the pain can last up to 12 hours. Others cats to stay away from are the Buck, Flannel, Hag, and Spiny Oak-slug moth larvae. Or in this case those ‘hairy’ little caterpillars.


There will be times when you may need to move a caterpillar perhaps from plant to another or into a rearing container to study it up close or maybe for photography purposes. If you do need move a caterpillar there are some points keep in mind. The first is if a caterpillar is off to the side or remains motionless from a few hours to a day, it is probably shedding it older skin and should not be touched. Otherwise the safest way to move a caterpillars is with a number two sable artist brush.  Place the tip of the brush underneath the caterpillar’s head. While very slowly rolling the brush in an away motion while sliding the brush tip underneath the head and then the abdomen. This rolling away motion will cause the caterpillar to roll up and onto the brush tip. Take the caterpillar while it is on the brush tip and place it onto the next leaf. Once the back end of the caterpillar is in contact with the surface slowly reverse the process by rolling the brush in a backwards motion and unroll the caterpillar onto the new leaf.


A very important point to remember is that whenever you are handling caterpillars make sure that your hands are clean. Many things that you come in contact daily with such as petting your dog or cat that has been treated with a topical remedy for ticks and fleas may kill your larvae. Enough residue can remain on your hand that it will transfer onto your caterpillar quickly kill it. You must also be very diligent with any aerosols and insect sprays that can drift onto your caterpillars or onto your hands. Handling other plants that have been treated for insects before touching a caterpillar could also be fatal to it. Most important of all when if you come in contact with white milky latex of the milkweed plant never let it come in contact with your eyes! You can damage your corneas and end up spending several days in pain and quite possibly the hospital as well. So always wash and dry your hands very thoroughly before and after handing any caterpillar, chrysalis or milkweed plant. Better yet wear throw away gloves when handling them.

Common Milkweed, Asclepias syriaca, loaded with monarch eggs

There is no rule of thumb to distinguish between butterfly and moth caterpillars. So do yourself a favor and get a good book to help you identify both groups otherwise you’ll drive yourself crazy. There are several guides out there that will even show the various life stages from egg through adult. We also have many photos available for you at to help you in your treasure hunt. There are also planting guides to assist you with your plant selection.

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