Life Cycle of the Lesser Waxmoth
Achroia grisella

Overview

Egg Stage Eggs are laid in cracks between hive parts or in groups on the upper side of cells, but I am unsure of size, colour or precise appearance as the picture has been synthesized from a monochrome photograph. Wax moth eggs hatch into larvae after five to eight days depending on ambient temperature. The eggs require a damp atmosphere to hatch.

Larval Stage Freshly hatched larvae burrow into the comb towards the midrib, the picture shows the hole a little higher up the cell than generally occurs, often the hole is so low in the cell it forms part of a semicircular gutter that is chewed out of the midrib itself. They are gross feeders and grow and feed for between one and six months depending on ambient temperature. When larval growth is complete they are 16 mm - 20  in length and look rather like a caterpillar. They have a reddish brown, dome shaped head, creamy white bodies with three segments that have a pair of legs and several other body segments, some of which have caterpillar style prolegs. The body colour changes slightly and progressively, with advancing age, to a light grey, occasionally with a pink or salmon pink tinge. The grub eats beeswax, but needs additional detritus within the comb structure (bee cocoons, feaces and pollen) to provide protein. All the while the larva is tunneling it leaves a fine silken tube and charcoal grey granular feaces behind it along the track that it has followed.

Foundation is only partially attacked, usually around the edge where the wax fits into the groove in the wooden frame parts. This damage is caused by small larvae that have not found sufficient edible material, they stay small and as they are inadequately fed they often die before reaching adequate size to pupate. I conjecture that in the inadequately fed larvae, at some moults, the new skin remains the same size (or possibly smaller) than the one it replaces. [1]

Spinning

Pupal Stage On completion of the cocoon the larvae itself changes to the pupal stage. Wax moth pupae may hatch rapidly or take up to two months to change to the adult stage depending upon temperature. Pupation can occur within the comb or in the loose debris at the bottom of the hive, but most frequently it is firmly attached to the frame or hive woodwork, particularly in places where there is an internal angle in the woodwork. The cocoon is cemented into a boat shaped cavity the larva chews in the wood. I assume that the cellulose mined from this cavity is converted into the silk that is used to make the cocoon and may account for the difference in silk texture. The pupae are about 12 mm long cigar shaped with the maximum width in the middle at about 3 mm. As the adult has no working mouth parts, I am unsure how it emerges from the cocoon, it certainly comes out of one end and leaves an almost circular flap, but how this is achieved... I do not know.

Adult (Breeding) Stage Adult Wax Moths cause no direct comb damage because their mouth parts are atrophied. They do not feed during their adult life. [2] Habits Male Males do not rely solely on pheromones to find a mate they also use ultrasound. The moths can often be observed vibrating, but otherwise immobile. I find this difficult to understand as their energy is restricted to that which they had emerged from the pupa. To explain this use of a resource that is in short supply I have a few guesses as to the reason for this behaviour...

This must be involved with finding a mate.

The vibration may be a by-product of emitting ultrasound.

Infrasound may be used as well as ultrasound (infrasound will travel long distances in solid media).

In appearance rather like a clothes moth 10 mm to 15 mm in length, with wings folded at a shallow angle over the top of the body. The wings have scales and are a slate grey or dirty brown sometimes with a minor bronze tinge. The bronze colour becomes more apparent if you squash one with a finger.

Female lesser waxmoths can produce up to 300 eggs and prefer to lay them in close proximity to used brood comb.

Differences for the greater waxmoth Galleria mellonella

Colour of adults is slightly more pink than the illustration at right. Grubs are pearly white initially, turning mushroom grey as they age. They are larger than Achroia larvae and more tapered at the back end.

The cocoons are larger and the pupae inside them are a light golden brown, There is more silk produced that almost knits the frames together. The damage to woodwork is considerable as the pupating grubs gnaw deep scallops in the woodwork. I have personally seen frame parts that have been perforated by larvae. The damage shown at right is only a medium level of infestation... I have seen much worse cases. This damage is further exacerbated by sheer numbers of pupae involved.