Managing Your Inventory

Planning Percentage Losses
in Each Stage of the Lifecycle

Linda Rogers and Jacob Groth,
with input from Melanie McCarthy and Nigel Venters.

For planning purposes to ensure you will have enough butterflies to fill all of your orders, it’s a good idea to build the loss numbers into your rearing operations and into the orders that you place with livestock suppliers. Each area of the country has different challenges and there are regional factors to consider such as heat, humidity, parasites, etc. So, to avoid the disappointment of shortage, experience will teach you to build in buffers. Some losses are encountered in shipping, also.

This “overage” estimate should be used when ordering livestock from another breeder. You should plan to purchase the estimated overage, and not expect the supplier to build this into their shipment to you! This is simply part of the cost of doing business, whether you are figuring your estimated losses in your own rearing operation, or determining how many “units” of livestock to order from a supplier.

Below is a planning formula that is being shared by Jacob Groth of Swallowtail Farms, Inc. to help breeders manage inventories. This formula is used every day to ensure an overage in production to be able to fill orders. The same numbers should be used when ordering livestock.

GOAL	STAGE	OVERAGE %
314	# of Eggs
235	# of Larvae Days 1-7	75%
176	# of Larvae Days 8-14	75%
167	# of Pupae	95%
150	# of Butterflies	90%

If you want to produce 150 butterflies, write that number in the bottom left block in GOAL column.

Divide 150 by 90%. That answer is how many pupae you need to produce.

Divide the 167 pupae by 95%, and that equals how many last instar larvae you will need to raise.

Divide the 176 larvae by 75%, and that equals how many early-instar larvae you will need to raise.

Divide the 235 larvae by 75%, and that equals how many eggs you will need to produce.

So, to produce 150 butterflies, you will need 314 eggs, 235 little instars, 176 large instars,

and 167 pupae. The percentages provided are “averages” and are based on experience raising livestock in sterile conditions, with adult butterflies housed outdoors in a flight cage.

Nigel Venters and Melanie McCarthy would advise you to save the “extra” eggs when you have them. Extra eggs can be placed in an airtight container lined with paper toweling, labeled with the date they were laid. Eggs will remain viable for up to 9 days, at refrigerator temperatures of not lower than 45 degrees Fahrenheit. (Always sterilize the eggs with Oe Solution upon removing them from the refrigerator to let them hatch, and not before you put them in the refrigerator!)

Building overage numbers into livestock orders and raising operations will reduce the worry associated with losses and inability to fill your orders.