Fly Larve, An Easy and Odorless Way

Abstract

Introduction

Fly larvae have been used for many years as a live food for captive birds. Until recently, culture methods have usually involved the use of rotting meat which is objectionable both because of the odor and the necessity to cleanse the larvae prior to using them for food.

In a very interesting and amusing article, Sir Godfrey Davis ( 1966) describes a number of rather unusual culture methods. While in India he discovered that decomposing bran was a successful medium for breeding house flies, but he was unable to get them to reproduce in this way in the more temperate climate of England.

Moistened Purina dog chow placed in the shade during warm weather will induce flies to oviposit and provides a satisfactory food for larval growth. Presumably any of the prepared dry dog foods would work as well and large numbers of larvae may be raised in this way. Methods which involve attracting flies and inducing them to lay eggs on prepared media are dependent however on suitable weather conditions, and thus are effective only during periods of relatively warm weather.

A number of methods are available to maintain a continual culture the year around. The more recent methods, such as those of Ficken and Dilger ( 1961 ), and Spiller ( 1966), involve the use of yeast supplemented milk products as the larval food. The method presented in this paper uses dog chow as the primary food, is quite simple, odorless, requires little time to maintain, and will produce large numbers of larvae.

Materials and Methods

The first essential is a suitable cage to house the adult flies. This can be of any design, but should be constructed in such a way that it can be cleaned and sterilized easily. Figures I and la illustrate such a design. It is made in three parts: a base, the wire screen, and a small drawer which slides into one end. An 18 inch length was chosen because this is the smallest width of galvanized screen that is commercially available. The cage is 8¥s inches high and 6 inches wide. This size will maintain a culture of 75-100 flies. The drawer is about 8 inches long. 2 3/4 inches wide and 1 1/2 inches deep. The two cut ends of the screen are each stapled co a scrip of wood and attached co the base using bolts and wing-nuts. The wood portions should receive at least two coats of a gloss or semigloss paint to keep the cage easy to clean. The small drawer in one end gives easy access to the cage and is used to hold food. water. and breeding medium.

A fly culture may be started in either of two ways. Adult flies can be caught and introduced into the cage, or moistened dog chow can be used to attract flies to oviposit. and either the eggs or the larvae placed in a rearing medium. The simpler way is to use the eggs. These are laid in small white masses which can easily be removed and placed in the rearing med ium. Two species of blow flies (family Calliphoridae) have been used. These have been identified as Phaenicia cuprina and Phaenicia sericata. Cuprina is a greenish bronze color and sericata is a bright metallic green. Both are very common, particularly around decaying organic matter, and culture of either species should be relatively easy.

Adult flies do well at a temperature of 80 degrees F. Their food mixture consists of two parts of ordinary granulated sugar mixed with one part of Brewer's yeast. Water is supplied by a moistened piece of white facial tissue. The containers for these as well as for the ovipositing medium are made from cut-down 5-oz. plastic cups. These fit easily into the small drawer.

The diet of sugar and Brewer's yeast will maintain adult flies nicely, but will not induce them to lay eggs. For this purpose an enriched medium is required. This is made as follows:

1. Powdered milk I volume

2. Brewer's yeast I volume

3. Hot water 15-20 volumes

4. Purina dog chow

Let sit until the dog chow is thoroughly softened.

5. A small piece of raw liver may be placed on top of the moistened dog food as an additional incentive. This is not absolutely essential, but may result in a larger number of eggs being laid.