Introduction
Methods
1) Setting up and maintaining a Rearing Bin
Figure 1: Lid of a Rearing Bin.
Larger Figure 2: Stack of cardboard half egg trays.
Larger Figure 3: Rearing Bin filled with stacks of half egg trays.
Larger Figure 4: Oviposition dishes filled with moist vermiculite.
Larger Figure 5: Breeding Bin with oviposition dishes.
Larger Figure 6: G. pennsylvanicus eggs deposited in water vials.
Larger Figure 7: Layer of eggs deposited in an oviposition dish.
Larger Figure 8: Ground food scattered on the floor of a Nursery.
Larger Figure 9: Hatchlings added to a new Rearing Bin.
Larger Figure 10: Very high density of hatchlings in a Rearing Bin.
Larger 2) Modification for egg laying (Breeding Bin)
Fill each 500-mL deli container with vermiculite to near the brim, and add one cup of tap water to each
– these are now your two oviposition containers (Fig. 4). Remove the third stack of half-trays from the bin and discard
half of them. Place the two oviposition containers in the bin and then place the egg carton lid upside-down on top
of the oviposition containers – this will keep the remaining stack of half-trays from sitting directly on the wet vermiculite
and wicking up the water. Place one of the discarded half-trays in between the oviposition containers and the wall of the bin
– this will keep the oviposition containers from sliding around. Then place the remaining
stack of half-trays on top of the oviposition containers (Fig. 5). Make sure that none of the cardboard is touching the
surface of the oviposition material as this will soak up water and cause mold problems on the cardboard. Depending on how dry
the room is you may have to moisten the oviposition substrate more frequently than you replace the dishes. Females will
lay eggs in the cotton of the water vials (Fig. 6); the cotton can be buried in moist vermiculite and kept with the main oviposition
containers (why waste the eggs?).
3) Setting up a Nursery and transferring hatchlings to a new Rearing Bin
Cut a window in the lid of the small plastic bin and cover it with aluminum screening and mesh as
with the large plastic Rearing Bin. Place the oviposition containers in the small plastic bin, along
with the cotton-plugged water vial (remember: make sure the cotton is not too loose or tight), and a little ground food scattered
on the floor of the bin – this is the Nursery (Fig. 8). Every day thereafter check the Nursery for the first newly hatched
crickets.
4) Cleaning the Breeding Bin
5) Breaking diapause in G. pennsylvanicus
6) Variations and Additional Notes
Note on environmental conditions: I rear G. pennsylvanicus at 25°C and 70% relative humidity with a 12 hr: 12 hr light cycle.
If you are raising a cricket species that doesn’t require diapause, then simply move the oviposition containers from the Breeding
Bin straight into a Nursery. With A. domesticus, Gryllodes sigillatus and T. oceanicus I’ve found that hatching occurs
roughly 14 to 21 days after the oviposition containers are moved into a Nursery.
Ground crickets do well under the conditions I've outlined. For Allonemobius spp. and Eunemobius carolinus I also put
their eggs through a 3-month cold period to break diapause. Allonemobius females seem to lay eggs into fine vermiculite in
large numbers. However, E. carolinus always lays eggs in the water vial cotton and never in the vermiculite. This is probably
because their curved ovipositors are adapted to inserting their eggs into some plant material. If anyone has had success getting eggs
out of E. carolinus or knows what plant they oviposit in in nature, please contact me.
If the room that you house your crickets is very dry and/or hot, you may notice the water vials going dry fast.
You may want to add more water vials or replace them more frequently. Just make sure that the crickets always have access to water.
Depending on the species being raised, you may want to adjust the height of the stacks of half-trays of egg cartons. I keep them
fairly high for G. pennsylvanicus and T. oceanicus, but remove a few layers for A. domesticus and G. sigillatus
because the latter are more prone to jumping out of the Rearing Bin.
I seem to get much better egg production using finely-ground vermiculite but this may not be readily available. I order it from Plant
Products Inc. (314 Orenda Rd., Brampton, Ontario; phone: 905-793-7000). Other possible oviposition substrates that I’ve heard of
people using are: sand, cotton, peat moss, soil.
I feed G. pennsylvanicus Martin “Little Friends” rabbit food (Martin Mills Inc. P.O. Box/C.P. 130, Elmira, Ontario, Canada
N3B 3A2; phone: 519-669-5171; www.martinmills.com). I started out feeding them Purina cat chow, but found that this food was
inadequate for rearing crickets individually from hatching to adulthood. T. oceanicus prefers cat chow, Gryllodes
sigillatus seem to like the rabbit chow and A. domesticus do well on either. Ground food for the first week or two,
with pellets added gradually thereafter.
Getting cardboard egg trays can be somewhat problematic as they are expensive to ship. If money is no object, then you
can order egg trays in bulk from www.eggcartons.com. However, I have cultivated a close relationship with the local
university residence dining hall, whose staff have been kind enough to save their used egg trays. An alternative to a university dining
hall is a popular local breakfast joint.
The following is a detailed description of husbandry techniques that I
use to raise crickets, specifically the fall field cricket, Gryllus pennsylvanicus.
In addition to G. pennsylvanicus, I have used these techniques (with some slight variations
described at the end) to successfully rear the following species: Acheta domesticus, Teleogryllus oceanicus, Gryllus
texensis, and Gryllodes sigillatus (all field crickets), as well as Allonemobius spp. and Eunemobius
carolinus (ground crickets). "Success" in this case means the production of cricket numbers (with a roughly even sex ratio)
that were limited only by the volume of space that I could allocate to them. It goes without saying that the high density rearing
conditions described are "unnatural" and no doubt contribute to persistent selection pressures that may result in adaptation to
the lab environment. What can I say but caveat emptor?
The primary motivation behind preparing this information is to set down a detailed training
manual that I can pass on to undergraduates just starting in the lab. Academic colleagues have also expressed interest in such a
document. Additionally, in the course of chatting with many a pet store clerk while buying food for the crickets, I realized that there
is quite an appetite for this sort of thing in the non-academic world - this page is also for people who need a steady supply of
crickets for their pet reptile/amphibian/arachnid/etc.
So please feel free to use as much or as little of this information as you like. Adapt it to
your own situation. I hope that it's helpful. I make no claim on the originality of these methods, as most of them were passed on
to me in discussions with other researchers. Of particular help have been chats with Mark Fitzpatrick (University of Toronto Scarborough),
David Gray (California State University Northridge) and Luc Bussière (University of Stirling), all of whom have extensive
experience rearing gryllids (G. texensis, A. domesticus and T. commodus respectively – the latter relaying knowledge gleaned
from John Hunt, University of Exeter). Also, many thanks must go to Darryl Gwynne (University of Toronto Mississauga) for his support and encouragement
throughout my PhD, and for allowing me free reign with a study system that was new to the lab. For the reader interested
in the literature on rearing field crickets, I would encourage them to read Wineriter and Walker (1988. Group and
individual rearing of field crickets (Orthoptera: Gryllidae). Entomol. News 99:53-62).
If you encounter difficulties with the protocols outlined below, or something isn’t clear, please feel free to contact
me (kevin.judge[at]uleth.ca). Also, if you have suggestions, send them along, I’m always game to improve things. Good luck, and happy cricket rearing!
This document starts with the basic instructions for setting up a: 1) Rearing Bin, which is all
you need if all you're concerned with is keeping crickets alive for as long as possible. But if you're also interested in maintaining a
colony, I then describe how to turn the Rearing Bin into a: 2) Breeding Bin, and how to collect newly hatched crickets
from a: 3) Nursery. Then there are sections on: 4) how to regularly clean a Breeding Bin, 5)
breaking diapause in G. pennsylvanicus and other egg-diapausing species, 3) a daily and weekly
schedule for cricket colony maintenance, and 6) additional tips including some
suggestions for modifying the methods for different species.
Materials:
Prepare the plastic storage bin lid by cutting a large window in the plastic and hot-gluing aluminum screen to cover the
window. Then hot-glue a layer of fine fabric mesh on the outside of the aluminum screen (Fig. 1): this will keep hatchlings
from escaping from the bin.
Start by tearing each egg tray in half (5 by 3 egg cups, Fig. 2) and making three stacks of 16 half-trays.
Make sure that the half-trays alternate in orientation (i.e. always cup side up, but alternating the torn and outside edges, Fig. 2). This orientation allows
for: a) lots of small spaces where small individuals can escape from larger individuals (e.g. when moulting, etc.), b) lots
of surface area for crickets and thus higher densities, and c) neat stacking which makes cleaning and removing individuals less
troublesome. Before I adopted this technique of stacking the egg trays, I often found that the sex ratio that emerged from rearing
bins was highly female-biased. This could be a problem if your primary interest is the study of male cricket behaviour, and several
other researchers mentioned that they were having "problems" with a female bias in the adults emerging from their colonies. I have since found
that females grow faster and larger than males, and given that field crickets
are highly cannibalistic, I surmise that under conditions of high density the larger individuals (primarily females) would prey
upon the smaller individuals (primarily males). Needless to say, when I started stacking the egg trays carefully as outlined above,
the adult sex ratio became much more balanced.
Place the three stacks of half-trays in the large plastic bin (Fig. 3). Fill the plastic vials with tap water
and plug with cotton; not too tightly as this will prevent moisture from soaking out, and not too loosely as very small crickets
(particularly hatchlings) will get stuck in the surface tension of the water soaking the cotton. Also make sure that the cotton
is pushed below the rim slightly because if it contacts the cardboard in the bin, water will wick out. Place a water vial on top
of each of the stacks of half-trays, and the remaining two on the floor of the bin: put in a piece of cardboard so that it won’t
roll from side to side if the bin is jostled (i.e. so it won’t crush any of the animals) (Fig. 3). Sprinkle food around the bin, but
don't overfeed as this will result in mold problems when uneaten food rots. I replace the water vials once a week, although they
may run dry sooner if the room is very dry. Also, I check on the food every 2 to 3 days and add food as needed. I would never leave
a bin unchecked for more than a week.
When you start noticing eggs being deposited in the cotton of the water vials, it means you've got some breeding
adults. It is not necessary to search through your Rearing Bin to find the adult crickets and remove them to a new bin. This is
time-consuming and can cause mortality to the smaller juveniles who are taking longer to mature. Instead, by making some simple
alterations, you can now convert your Rearing Bin into a Breeding Bin and start collecting eggs to produce the next generation of
your cricket colony.
Materials:
I replace the oviposition containers (i.e. new moist vermiculite in a new container) once a week when
I replace the water vials. After one week of egg-laying, the old oviposition dishes should be crammed with eggs (Fig. 7) assuming
you've got at least several dozen females and enough males to fertilize them in your Breeding Bin.
If you're raising a species that does not require a cold period to break diapause (e.g. A. domesticus or T. oceanicus)
then you should now set up a Nursery from which you can collect newly hatched crickets to place them into a new Rearing Bin. Put
lids (with several small air holes) on the oviposition dishes and place the dishes in the room where you are rearing your crickets.
Hatching for non-diapausing species occurs roughly 2-3 weeks after the dishes have been taken out of the Breeding Bin. After
approximately 10 days, remove the lids and place the oviposition dishes into a Nursery.
Materials:
Once you have newly-hatched crickets, add them to a new Rearing Bin. To do this,
take the oviposition containers and water vial from the nursery and place
in a spare plastic box. Now dump the hatchlings from the nursery box into the Rearing Bin. Scatter a bit of food over the top
of the stacks of half-trays and the floor of the Rearing Bin (Fig. 9). Put the oviposition containers and water
vial back in the Nursery and scatter a bit of ground food on the floor. Don't worry about trying to coax stragglers from the
oviposition dishes, they'll jump down on their own. Keep the oviposition substrate moist. The advantage of using a Nursery rather
than simply putting the oviposition dishes right into a new Rearing Bin is that you'll be able to see exactly when hatching declines
and stops. Then you can simply discard the old oviposition dishes, which would otherwise be a haven for fungus, etc. in a new Rearing Bin.
If you dump hatchlings from the Nursery into the Rearing
Bin every couple of days, then the newly-hatched crickets will be fine. If you need to leave the Nursery for more than a few days,
then put cardboard in there so that if they need to moult then they’ll have something to grip onto. It’s obviously easier if
you just dump newly-hatched crickets fairly often – you may want to do it every day or more often if you’ve got a lot of crickets hatching.
At some point, the Rearing Bin to which you are adding hatchlings will become too crowded to add any more (Fig. 10) and
you’ll have to start a second new Rearing Bin. I have no good suggestions on how many hatchlings to add before it’s necessary
to start a new Rearing Bin. I usually take a look within some of the layers of the egg trays – if the inner layers look chock
full then it’s probably time to start a new bin. I have not done any scientific assessment of survival as a function of starting density.
Each new Rearing Bin should have a label stating when hatchlings first started going in – this will give you a
rough guide as to when you should expect the first adults. Make sure that the crickets have constant access to food and water,
but don’t overfeed as the food can go mouldy if there’s too much of it. It is better to add food every few days then to add it
in bulk less often. I just scatter food around the bin (on top of the cardboard and down the sides onto the floor) and don’t
bother to put it in dishes – the crickets don’t seem to mind, they often take pieces of food to some place inside the layers
of egg cartons anyway.
When adult crickets age, their frass turns runny and will stick to the surface of the egg cartons and Breeding
Bin. So once you’ve started a Breeding Bin it is a good idea to clean out frass and dead crickets regularly. (Note: this is not necessary
with a Rearing Bin as I rarely see dead juvenile crickets lying about - probably eaten by their comrades - and the accumulating frass is
all dry pellets.) I clean the bins, replace oviposition containers and water vials once a week. If you don’t clean out the dead crickets regularly, you may
end up with an infestation/outbreak of mites. In the past, I've only ever had problems with mites when there are lots of dead crickets
lying around. I think (hope?) that these mites are simply commensals feeding on the dead carcasses and not also parasites of live animals.
When I clean the Breeding Bin weekly I never notice mites. Also, be sure to get rid of the garbage in your cricket room often if there
is a lot of this dead cricket material in it – mites can explode in numbers in the garbage.
To clean the bins, gently take the stacks
of half-trays and place them in one or two spare large plastic bins. Then gently transfer the leftover live crickets into the spare
bins, leaving behind frass and dead crickets. Dump this material into the garbage. Now, while they're in the extra plastic bins, take
apart the stacks of half-trays one layer at a time and gently tap off the crickets and accumulated frass. Restack the half-trays in
the original Breeding Bin, add oviposition dishes, water vials and food and then transfer the crickets back leaving the frass and dead
crickets behind. This can be a bit tricky if you don't have the patience to transfer them by hand, but it's doable if you're careful.
Simply take the empty plastic bin with the live crickets and frass, and gently turn it on end with the edge of the bin just resting
over the newly cleaned Breeding Bin. If the bin is slightly tilted down then the crickets will slide or run off the edge and into the
Rearing Bin. You may have to stop once or twice to chase a cricket that jumped onto the floor, but you can minimize this by placing
empty plastic bins around the edge of the Breeding Bin. Note that A. domesticus and particularly Gryllodes sigillatus are
extremely jumpy and this method of transfer may be impossible.
After a while you’ll notice that the density of crickets is getting pretty low and it doesn’t make sense to maintain an
entire bin for just a few crickets. When this happens I just remove all the egg cartons and water vials and transfer the remaining crickets
to the next-oldest Breeding Bin (why waste crickets?). However, if you're concerned about possibly spreading disease between
bins you may not want to do this.
G. pennsylvanicus requires a period of cold at the egg stage in order to break diapause and hatch.
This is the primary difference between rearing G. pennsylvanicus and other species that are continuous breeders.
Once you’ve removed the oviposition containers from the Breeding Bin, place lids on the containers (I put
holes in the lids with a mounted needle, but I’m not sure whether it’s necessary). The containers sit at room temperature
for a week before going into a refridgerator set to 4°C. I keep eggs in 4°C for three months, but
this can be shortened to two or lengthened to four months without any noticeable effect on hatching success. However, this is
just based on trial-and-error, I have not done any systematic experiment on the optimum duration of diapause. I also keep the
eggs in a box with no control over light levels – I have no idea whether light levels during diapause may have an effect on development.
Remove the oviposition dishes from 4°C and leave for around 10 days with the lids on in the room where they
will be raised. This will keep the vermiculite moist and unwanted organisms out of the containers. If there is fungus growing on the surface,
you can open the lid to dry it out – disrupting the fungal hyphae by running a mounted needle through the top few millimetres of
vermiculite will help to kill off the fungus, or at least knock it back. I’ve found that crickets still hatch even if there is
a solid layer of fungus on the surface (so all is not lost if you have fungus growing). Under these conditions, I’ve found that
G. pennsylvanicus from Mississauga, Ontario hatch 15 days after they’re removed from 4°C.