I have found all types of Canna to be excellent as food-plant - species Cannas, showy flowering types, purple-leaved varieties, there is a cultivar with variegated leaves which is a little slow-growing, so should be avoided for this reason, but it is still readily taken by Caligo larvae.  Most of the available Caligo species (memnon, eurilochus, atreus, beltrao) appear to take Canna as a suitable food-plant, although some will lay on banana as a preference if it is available. Certainly, if you obtain ova or small larvae, as opposed to having gravid females, you will experience no problem in getting the larvae to feed on Canna.  Beware low night temperatures - the Caligo larvae feed mostly at night, so it is of no use keeping the temperature at 75-85ºF (24-30ºC) by day, only to let it fall to 60ºF (15ºC) at night. For rearing Caligo larvae, a recommended night temperature is 70-75ºF (21-24ºC).

Exactly how many Cannas you will need for feeding a batch of Caligo larvae is hard to say. Let it suffice for me to state that you will need three to four times as much as you think you will need!  Andrew Booth (AES Bull. Vol. 48. No. 366. Oct 1989) calculated a single larvae of Caligo beltrao to consume approx. 3030cm² of banana leaf (Musa cavendishii ??) and the rearing conditions were stated to be "on top of the TV". We can assume from the conditions of low humidity normally associated in the "Living room" and especially on top of a television set, that the larvae was reared under considerable stress. In more ideal conditions, where these can be achieved, I would expect that the larvae would consume even more food-plant and I suggest it is not unreasonable to expect a 25-50% increase in consumption.  Therefore if you are aiming to rear large, healthy specimens under optimum conditions, then allow for 5000cm² of leaf per larvae - yes, before you wonder if I have made an error, I really am suggesting you allocate ONE SQUARE METRE of food-plant leaf for each pair of larvae that you rear.

No similar calculations that I am aware of have been made for Canna or any of the other Caligo food-plants, I can only say that I have not noticed a vast difference in consumption between the two plants (Musa & Canna) when larvae of the same species have been reared on both plants simultaneously. Bear in mind also, that it is not good practice to allow plant leaves to be wholly consumed, unless you wish to grow new each time. It is wise to allow plants to rejuvenate after 50% of their leaf has been consumed.

As Cannas begin to die back at the end of the season, the tops can be cut off and the corms lifted and cleaned and divided. They should be stored dry in darkness (much the same as with Dahlias) at 10ºC (50ºF) until the following spring.

Happy Growing!

Paul Batty. December 1999.

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