272 
Sense of Smell in Insects . 
[May, 
scent must not be omitted : they can be readily applied to or 
turned towards objects to be examined, and this in a discri- 
minating manner. Dr. Wolff’s organ, on the contrary, does 
not admit of being specially applied to minute objects or 
thrust into crevices, as is done by, e.g., the ichneumons in 
their search for latent larvae or pupae. 
We now come to the conclusive test of direCt experiment. 
For this purpose I have selected certain lamellicorn beetles. 
These insedts, if suitably fed, can live for a considerable time 
in captivity, and, if not roughly handled or startled by sudden 
and abrupt movements, they show a certain degree of docility 
— I might even say of attachment. My first observations of 
this kind were made, many years ago, upon a very large male 
stag-beetle which lived in my vivarium for about a year.* 
If I took him out and set him upon a table he would travel 
about with the leaflets of his antennae shut. If I held out 
a piece of pear or apple he would immediately advance his 
antennae, open the leaflets, and march straight towards the 
desirable morsel. When it was laid down for him to eat he 
always passed his antennae over it, just as a dog smells at 
any food given him. Having thus satisfied himself of the 
suitable quality of the food, he began to eat. With moistened 
brown sugar he behaved in a similar manner. 
I have since made similar experiments with common dung- 
beetles ( Geotrupes ). If these inserts were placed under a 
glass bell they remained quiet, or roamed listlessly about 
with their antennae contracted, and the leaflets of the club 
closed. If a portion of excrement was then introduced the 
beetles became attentive, moved the antennae about, opened 
the leaflets of the club, moved towards the dung, and 
examined it by applying the antennae just as did the stag- 
beetle with the slices of fruit. 
Similar experiments were made at different times with 
many specimens of the rose-beetle ( Cetonia aurata). On 
offering these beautiful inserts sugar or flowers — such as 
whitethorn or elder blossom — their behaviour was precisely 
the same as that of the stag- and the dung-beetles under 
similar circumstances. 
InseCts which do not possess club-formed or lamellate 
antennae are less suitable for such experiments, as the ve^ 
characteristic phenomenon — the expanding the leaflets or 
plates of the club — is necessarily wanting. But even spe- 
cies possessing simple antennae behave in a similar manner. 
* After his regretted death he was transferred to my coiledtion of Coleoptera, 
and measures 3! inches from the tip of the jaws to the posterior end of the 
elytra. 
