A winged Camponotus pennsylvanicus queen. Photo courtesy of Max Hike.
General Information
Ranging from Florida and Maine in the east, all the way to New Mexico and North Dakota in the west, Camponotus pennsylvanicus is one of the most recognizable and quintessential ant species in North America. Commonly known as the “Black Carpenter Ant,” it may be surprising to learn that Camponotus pennsylvanicus — and other Camponotus for that matter — don’t eat wood. Unlike what many pest control companies would have you believe, Carpenter ants aren’t going to invade your house and dig through its walls as they wish. In fact, as long as your house isn’t made of wet, rotting wood, there is no risk of an infestation. Camponotus pennsylvanicus, and all other wood-nesting Camponotus, only nest in wood that is in the process of decomposing.
Sting?
Camponotus pennsylvanicus is a member of the Formicinae subfamily, which is characterized by its use of formic acid for both attacking prey and defending themselves from threats. Species in this subfamily do not have stingers. However — like all ants — Camponotus pennsylvanicus can bite. While most workers have jaws too small to meaningfully break the skin, majors can bite and then dab formic acid on the wound, which causes a small stinging sensation. Overall, this species is not dangerous, and is safe to be handled if necessary.
Nuptial Flights
Like other Camponotus species in the eastern U.S., Camponotus pennsylvanicus flies between April and June, depending on the state they are in. In southern states such as Tennessee and Georgia, flights may begin as early as April. Moving north to states like Ohio and Pennsylvania, flights will typically begin in mid May. Finally, colonies as far north as the upper Midwest and New England regions may not begin flights until early to mid June.
Typically, Camponotus pennsylvanicus has nocturnal flights, but some especially dense populations have been known to fly during the day. Nocturnal flights begin just before sunset, and can continue until the temperature drops below 70 degrees Fahrenheit. Often, the temperature when flights begin is at or above 75F°. These flights will continue on warm nights for 2-4 weeks. Not much is known about daytime flights, but similar or warmer temperatures to nighttime flights would be expected. Rain is not required for this species to fly, but significant rain on the day of a potential flight may postpone it, and can sometimes lead to a large flight the next day.
Founding
C. pennsylvanicus is a fully claustral species, so queens do not need food before their first workers hatch. Usually, egg to worker ranges from 6 to 8 weeks, with ~18 days in each stage, depending on temperature. Brood development will benefit from the use of a heat cable, growing more quickly as it warms. However, temperatures that are too high can result in higher mortality rates in both brood and workers, so we recommend keeping colonies at 80F° or lower, and providing a heat gradient. Heat gradients are made by placing the heating element at or near the entrance to a nest or test tube, which will allow for the ants to self-regulate their temperature, as workers will prefer a lower temperature than brood. Diurnal heating may have benefits to colony growth.
Like many ant species, the size of a pennsylvanicus queen’s initial clutch can have a lot of variation. Most queens will have between 4 and 10 nanitics, although some queens may have higher or lower numbers. Camponotus pennsylvanicus queens are known for laying trophic eggs, which are unfertilized eggs that will be eaten by their larvae as they grow. In extremely rare cases, queens will “forget” about these eggs, leading to the development of a male along with a limited clutch of nanitics.
Once a queen reaches her first workers, they will need to be fed. With proper feeding and heat, most colonies can reach 15-30 workers before their first diapause, although in some cases they can grow even more. After waking up the next spring, colonies will begin to grow exponentially. Often, this is also when they will begin to make their first majors, which are by the colony to aid in protein processing and food storage.
Feeding Preferences
A typical ant colony’s diet requires two things: proteins and carbohydrates. Carbohydrates come in the form of sugars, such as honey, fruit, nuts, or sugar water, and proteins come in the form of insects. seeds or nuts.Camponotus pennsylvanicus is no exception to this, commonly found in the wild tending to aphids or carrying away a dead insect carcass.
In captivity, Camponotus pennsylvanicus is often fed a diet of sugar water or honey to provide sugars, which can be supplemented with pieces of fruit to diversify their diet. It can help to cut off the skins first, as they can occasionally harbor residual insecticides. Ideally, colonies should have access to a sugar source at all times. For protein, antkeepers utilize a large variety of of common feeder insects (pennsylvanicus is not granivorous, so they will not eat seeds or nuts). They can be fed superworms, mealworms, red runners, and many other feeder species. Our personal recommendation is fruit flies, as they are low-care, require little cleanup, and have many nutrients that aid in growth. Protein should be offered at least once every few days, if not every day, depending on the size of the colony. Additional protein sources that can be offered 24/7, like fish food, may also benefit colony growth.
Nests & Escape Prevention
In the wild, Camponotus pennsylvanicus nests almost exclusively in wood, although colonies can sometimes branch out into the soil underneath their nesting site. However, in captivity they are well-suited to a wide variety of formicarium types. Pennsylvanicus colonies can grow and thrive in 3D-printed, acrylic, grout/UltraCal, wooden, or Ytong nests, just to name a few. It is recommended to scale nests as the colony grows, as too much space can lead to them filling unused sections with trash.
Similarly, a number of different barriers can be used to prevent C. pennsylvanicus colonies from escaping. Talc/baby powder and olive oil can both be used as effective barriers. However, I recommend using Fluon. Fluon is a highly effective barrier for all ant species, and can last as long as 4-6 months under the right conditions.
Hibernation/Diapause
Throughout their entire distribution, Camponotus pennsylvanicus require diapause. At the extreme low end of their range, such as northern Florida, this may consist of being kept in a cooler room (~60-65F) and being fed less than normal for a few months. However, most pennsylvanicus colonies will require a much cooler and longer diapause. I recommend using a wine cooler or minifridge set to approximately 40-50F, and keeping the colony in hibernation for 3 to 5 months. In the absence of a wine cooler/minifridge, putting them in a box with some insulation in the form of towels, and then placing the box into a regular fridge will suffice.
To prepare for hibernation, make sure to feed C. pennsylvanicus colonies as normal throughout the month leading up to it (usually September or October), even if the queen stops laying eggs. This will allow the workers to fill up on food in preparation for the cold winter months. At some point during this process, larvae will stop developing once they reach a relatively small size (the second instar), this will signal that the colony is ready to hibernate. Wait until the final pupae (and any developing larvae) eclose into workers, and it will be time to place them into the wine cooler/fridge/minifridge for diapause.
Throughout diapause, check on them once every 2 to 4 weeks to make sure that the colony still has enough water. Like many Camponotus spp., Camponotus pennsylvanicus will often appear to curl up and “die” during hibernation. However, this is a perfectly normal process and occurs due to a buildup of natural antifreeze in their system. Rest assured, they’re not dead! In the wild, this process allows them to survive the below-freezing temperatures that Camponotus colonies are subjected to in their aboveground wood nesting sites.
After 3 to 5 months (often in February to April) it will be time to take the colony out of hibernation. To do this, simply bring them back out of the wine cooler/fridge/minifridge to room temperature. This doesn’t have to be done slowly, but it is important to keep a close watch on any test tubes, as they are prone to flooding due to water quickly expanding as it changes temperature. This can be alleviated by keeping any test tubes with the colony vertical until they have warmed up. Make sure to immediately move the colony out of any tubes that have flooded.
At first, it may not seem like any ants are moving, but soon the workers’ antennae will begin to slowly wave around, and then their legs will regain the ability to move over a few hours. The queen, on the other hand, may take up to two weeks to wake up from diapause and no longer appear dead. The antifreeze takes longer to fully remove itself from her system than the workers, and she may seem to wake up before curling pack up again for a period of time. This is normal, and should stop within a few weeks of removal from diapause.
After being removed from diapause, the pennsylvanicus colony will need to be fed within a day or two, as they will have used lots of their energy over the course of the last few months. within a couple weeks, the larvae will begin to develop again, and they’ll be hungry, so make sure to provide lots of insect protein! The queen will likely take up to 6 weeks to start laying again after diapause, and then colony growth will resume as normal.
Growing and Mature Colonies
Like most ant species, once a Camponotus pennsylvanicus colony has survived the founding stage, they’re much less likely to struggle going forwards. At this point, growth is exponential, and they’ll need to be kept well fed. While literature cites their maximum colony size as about 2000-2500 workers, this is hard to estimate as pennsylvanicus colonies are polydomous (and by some reports, even oligynous). Polydomous ant species are species that have multiple nest sites per colony, often called satellite nests when they lack a queen.
Regardless of their maximum colony size, colonies will typically begin alate production at around 300 to 600 workers, this is considered their mature size. While the first instinct may be to release these alates into the wild, this can be harmful to the local ecosystem. Since the vast majority of ant queens in the wild never survive to produce even one generation of workers, let alone to maturity, releasing alates from captive raised queens can “dilute” the good genes in the breeding pool of wild pennsylvanicus colonies, resulting in a weaker population that is less able to compete with the surrounding species in the area, and more vulnerable to diseases and parasites. As sad as it is, the most humane thing to do with alates from captive colonies of any ant species is to freeze them and feed them to other colonies.
While the colony grows, They might start to seem more difficult to take care of, requiring more food and cleaning, and escaping more often. But in reality, this can be the most fun and interesting stage of the colony! Once a colony reaches a large size, they’ll start to exhibit lots of behaviors unique to certain ant species. For example, in the case of Camponotus pennsylvanicus, polydomy. While many ant species only use a single nesting site for the whole colony, Camponotus spp. will often utilize multiple sites. This can be observed in captive colonies by placing artificial nests of varying sizes far away from each other, like on the other side of an outworld, or after a long tunnel of tubing.
A large colony is also the time to try out larger foraging areas. Camponotus are active foragers and will benefit from lots of horizontal (and vertical!) space to explore. This can also lengthen the lifespan of escape barriers, as the foragers will interact with them less.
Identification
Camponotus pennsylvanicus is a large, black species, whose gaster is covered in long hairs ranging from silver to yellow in color. Workers are 5-8 millimeters long, and majors can range from 10 to 17 mm. Their queens are some of the largest in the US, at 16-20 mm long. When filled with food/eggs, both worker/major and queen gasters can expand and appear to have stripes, but this is not an identifying feature as it appears in many other ant species.
At the genus level, Camponotus are often mixed up with Formica. In the US, these two genera can be easily separated by the presence, or lack thereof, of a bump in the middle of their mesosoma. Formica species will always have this bump, while Camponotus species will not. On a subjective note for field identification purposes, I find that if an ant is moving very fast, rarely stopping for long enough to get a good look at it, it’s probably Formica.
While color easily distinguishes Camponotus pennsylvanicus from most other Camponotus species, such as castaneus, novaeboracensis, and subbarbatus, there are a few that can, at times, be difficult to tell apart from pennsylvanicus. One such example is Camponotus chromaiodes, and others are Camponotus nearcticus and caryae.
Camponotus chromaiodes are typically very easy to differentiate from Camponotus pennsylvanicus, due to the red coloration on chromaiodes‘ mesosoma and front of gaster. However, there are some C. chromaiodes queens and workers that can appear completely black at first glance, and these can be difficult to separate from pennsylvanicus queens and workers to the untrained eye.
These “dark morph” chromaiodes will have some key differences to Camponotus pennsylvanicus that can make it easier to tell them apart. For queens, they will often still have a small region of matte-red coloration on their legs. At a minimum, Camponotus chromaiodes queens will have some red coloration on the front of their gaster, in darker morphs this can be very small, and easily obscured by their petiole, which the coloration would be directly behind.
Workers will also often have some matte red on their legs, however in some cases they can be completely black. In this instance, it is necessary to look at more subtle features, such as gastral pubescence. Camponotus chromaiodes workers will have long, golden hairs covering all parts of their gaster. While Camponotus pennsylvanicus can have long yellowish hairs, theirs will be distinctly less dense than the hairs of C. chromaiodes. This feature also works for queens, but is not usually necessary.
Camponotus nearcticus and caryae are two very similar species that can also be mistaken for C. pennsylvanicus, however, they can be easily separated by multiple characteristics if you know what to look for.
Firstly, both nearcticus/caryae queens and workers are easily separated from pennsylvanicus by their size. C. nearcticus/caryae workers are approximately 4.5-5 millimeters long, while majors are 6-8 millimeters long. Queens are 9-11 mm long. All of these are significantly smaller than their pennsylvanicus counterparts.
However, when looking at a picture of an ant — or even just with imprecise measuring — length can often be uncertain or unknown, making it sometimes necessary to look at other identifying features. In the case of nearcticus/caryae workers and queens, they are shiny across all body surfaces, with few distinguishable hairs, and much thinner than pennsylvanicus in stature. The latter is especially noticeable in queens.
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