Why are people reporting so many Monarch (and other species) of butterflies later in the year than normally reported? There are several simple reasons.
More people are noticing butterflies, especially Monarch butterflies. The internet has increased the number of people who recognize Monarch butterflies. More people understand the dates they should normally be absent in an area. They share the dates that they spot them in their area. In the past, when people would see the exact same species on the exact same place and on the exact same date they didn’t report it. It meant nothing to them.
More people are raising caterpillars indoors. This protects them from nature’s enemies, including cold temperatures. Many of the butterflies spotted were raised indoors. If they had been left outdoors, low temperatures would have killed them. There are more late-season butterflies because people save them from the weather.
Artificial lighting in communities and around houses often give a false sense of the time of year to caterpillars under the lights. This prevents them from going into diapause and/or migrating.
Late season butterflies aren’t a reason to panic. Nature will take care of them. If they are where it will freeze, they will die unless they are a species that survives freezing temperatures, such as Mourning Cloak butterflies.
Extra reports of late-season butterflies are a sign of good things: that people are noticing them and reporting them. When more people are aware of butterflies and their natural lives/life-cycles/timing, they are less apt to use insecticides in their gardens. They are more apt to plant butterfly host and nectar plants.
It helps to know which stage is a butterfly. When I do presentations for children or students, I always ask that question.
We have a BUTTERFLY egg (undeveloped butterfly), a BUTTERFLY child (young butterfly – caterpillar), a BUTTERFLY teenager (chrysalis – a maturing butterfly – going through sexual maturity), and an adult BUTTERFLY.
They are all the same organism, same critter, just one that is maturing. The caterpillar is not a different creature. It simply has a different appearance. The chrysalis is not a different creature. It simply has a different appearance.
A few years ago, a woman called our office, asking how she can kill the ‘worms’ eating her passion vine without harming the butterflies. She was unable to grasp the fact that the ‘worms’ (caterpillars) were butterflies in child form. Once people grasp that important fact, they begin to use less pesticides and plant more host plants.
Enthusiasts often run out of leaves for caterpillars and rush to the nursery to buy more plants. Then comes the BIG question: How long should I test it with one caterpillar before placing more caterpillars/leaves together? You won’t like the answer.
First, to be 100% sure, until it becomes an adult and flies away without problem. If a caterpillar is exposed just before pupating, some insecticides won’t affect them until they emerge as adults. If some pupae are exposed, it won’t affect them until they emerge as adults. The adults will expand and dry their wings, but when they start to fly around, they go into spasms, usually eventually dying with their wings folded over their legs.
Next, at least into chrysalises. Some insecticides (such as used in some oral flea/tick medications) will affect them only when they begin to pupate. The result is deformed or incomplete chrysalises.
If you don’t have that much time and MUST feed the leaves to your caterpillars, wait three days if at all possible. The certified organic pesticide, Bt (a natural soil-dwelling bacteria), takes three days to do it’s job. Three days after caterpillars eat it, the caterpillars die.
Many insecticides will cause almost immediate vomiting (green fluid that stays green) and sometimes convulsions. This isn’t a pain reaction. It’s a nerve reaction. The insecticide acts on certain nerves, causing the caterpillars to jerk around.
Bottom line – the longer the better, up to the adult emerging and flying away.
For folks who live in Florida, Southern Texas, and below Tuscon, Arizona, your pipevine plants may be visited by two different swallowtail butterflies. This can cause a problem because most plants that Pipevine Swallowtail caterpillars can safely eat will kill Polydamas Swallowtail caterpillars and vice versa.
There is a concern expressed by enthusiasts who want to remove the head capsule from a molting/molted caterpillar. Should you? Or not?
There are two beliefs on this. One belief is that, if it molted and can’t get its head capsule off, an enthusiast should remove it to allow it to eat and grow. The other belief is that, if it didn’t take it off naturally, removing it and allowing it to live and lay mate may pass on a defective gene, one that may have interfered with the molting process.
There is a challenge to be sure that it has finished molting. Removing it too soon will kill it. If it has been observed molting and it has been a while with the head capsule still on its mouth, what do you think?
Green liquid with caterpillars normally means either stress or insecticides. Some species immediately spit when they are touched. Skippers are notorious for this reflex. Other species tend to spit when they have been exposed to insecticides. Because of this, green stains in with caterpillars is a sign of possible problems.
But their hemolymph (comparable to blood) is also green. When we see green, how do we know if it is hemolymph or spit? Simple. Spit stays green and hemolymph turns dark within five minutes.
Use of insect spray/treatment even in rooms behind closed doors on the other end of the house can travel through the air and a/c ducts to the room where caterpillars are eating. A spray was used 30′ away from this habitat with closed doors between the habitat and the spray. Every caterpillar died.