When we last mentioned Johnson’s Ecology of the Bed Bug, I said we would go back and talk a bit more about his experiments. And we should.
Today we want to simply introduce the hut where some of these experiments were deployed:
A hut was made in which it was possible to liberate a number of bugs to prevent their escape and to keep count of them. This hut measured 8 ft. long x 5 ft. wide x 6 1/2 ft. high. It had a wooden frame of 3 x 2 in. timber and the walls were made of large sheets of ‘Sundela’, a hard compressed fibrous material 3/8 in. thick. The floor was made of a hard quality Sundela fastened to supporting timbers. All cracks round the floor, walls and ceiling were covered with wide adhesive tape. The walls and ceiling, which were quite flat and with no projections, were covered with offwhite distemper.
In the roof was a skylight 3 x 2 1/2 ft. and in one wall a door 2 1/2 x 4 1/2 ft. The bottom edge of the door was 11 1/2 in. from the floor.
In order to prevent bugs from escaping through the door and the skylight, strips of glass 2 1/2 in. wide were let into the Sundela walls so that both door and skylight were surrounded by a glass surface over which it was impossible for bugs to crawl.
The hut stood on legs 8 in. high, which rested on tiles placed in a shallow iron tray. The floor of the tray was covered with a layer of lubricating oil to guard against the slightest possibility of escaping bugs.
Habourages consisted of pieces of corrugated card (5 x 6 in.) fixed to the two opposite walls, 1 1/2 ft. from the floor. The hosts used were rabbits, guinea-pigs and fowls.
Johnson, C. G. 1941. The ecology of the bed-bug, Cimex lectularius L., in Britain. Journal of Hygiene 41: 345–461
I find this paper fascinating and I want us to explore it. I also just really like it because it was commissioned by the Bed-Bug Infestation Committee of the UK Medical Research Council.
Among other things, Johnson was immensely preoccupied by cold temperatures and overwintering effects, questions that seem not that important to us in our well-heated apartments—well, some of your apartments are well-heated at least, I hope. But I’m reminded that in some parts of the world, this issue is still relevant.
I want to quote a bit from an exploration of another question that is tremendously important:
For the greater part of the time a bed bug’s life is spent in a state of immobility, usually in corners and cracks about a room or in furniture. This inhibition of movement, so characteristic of Cimex, is induced by contact stimuli; for when a bug is lying in close contact with adjacent surfaces—whether these be the sides of a crack or the bodies of other bugs—and the insects’ contact receptors are sufficiently stimulated, the state of immobility is maintained until other kinds of stimuli occur to induce the bug to wander about.
A cluster of bugs ensconced in a crack may remain immobile for several weeks as the following observation shows:
Nine bed-bugs had been placed on a platform of stretched muslin in a large Petri dish at room temperature and 10% R.H. on 12 January 1939. They settled down in a cluster, and a piece of smoke-blackened cardboard was placed against them so that movements could be detected. A state of immobility was maintained for 35 days until overnight on 15 February they dispersed.
Researchers are making progress in advancing some of this knowledge. Something more is known, for example, about how bed bugs conserve water by clustering together in a quiescent state, Benoit et al. (2007).
But in general what we know about bed bugs (it seems to me!) may not be that far ahead of what Johnson knew?
So, more Johnson, soon.
By the way?
Sometimes the rabbits and guinea pigs ate the bed bugs.
These pages may be of related interest:
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