Passage adapted from “Camping Out” by Ernest Hemingway (1920)

Thousands of people will go into the bush this summer to cut the high cost of living. A man who gets his two weeks’ salary while he is on vacation should be able to put those two weeks in fishing and camping and be able to save one week’s salary clear. He ought to be able to sleep comfortably every night, to eat well every day and to return to the city rested and in good condition.

But if he goes into the woods with a frying pan, an ignorance of black flies and mosquitoes, and a great and abiding lack of knowledge about cookery, the chances are that his return will be very different. He will come back with enough mosquito bites to make the back of his neck look like a relief map of the Caucasus. His digestion will be wrecked after a valiant battle to assimilate half-cooked or charred grub.

And he won’t have had a decent night’s sleep while he has been gone.

He will solemnly raise his right hand and inform you that he has joined the grand army of never-agains. The call of the wild may be all right, but it’s a dog’s life. He’s heard the call of the tame with both ears. Waiter, bring him an order of milk toast.

In the first place he overlooked the insects. Black flies, no-see-ums, deer flies, gnats and mosquitoes were instituted by the devil to force people to live in cities where he could get at them better. If it weren’t for them everybody would live in the bush and he would be out of work. It was a rather successful invention.

But there are lots of dopes that will counteract the pests. The simplest perhaps is oil of citronella. Two bits’ worth of this purchased at any pharmacist’s will be enough to last for two weeks in the worst fly and mosquito-ridden country.

Rub a little on the back of your neck, your forehead and your wrists before you start fishing, and the blacks and skeeters will shun you. The odor of citronella is not offensive to people. It smells like gun oil. But the bugs do hate it.

Oil of pennyroyal and eucalyptol are also much hated by mosquitoes, and with citronella they form the basis for many proprietary preparations. But it is cheaper and better to buy the straight citronella. Put a little on the mosquito netting that covers the front of your pup tent or canoe tent at night, and you won’t be bothered.

To be really rested and get any benefit out of a vacation a man must get a good night’s sleep every night. The first requisite for this is to have plenty of cover. It is twice as cold as you expect it will be in the bush four nights out of five, and a good plan is to take just double the bedding that you think you will need. An old quilt that you can wrap up in is as warm as two blankets.

Nearly all outdoor writers rhapsodize over the browse bed. It is all right for the man who knows how to make one and has plenty of time. But in a succession of one-night camps on a canoe trip all you need is level ground for your tent floor and you will sleep all right if you have plenty of covers under you. Take twice as much cover as you think that you will need, and then put two-thirds of it under you. You will sleep warm and get your rest.

When it is clear weather you don’t need to pitch your tent if you are only stopping for the night. Drive four stakes at the head of your made-up bed and drape your mosquito bar over that, then you can sleep like a log and laugh at the mosquitoes.

Which rhetorical device is present in the underlined sentence: "Oil of pennyroyal and eucalyptol are also much hated by mosquitoes, and with citronella they form the basis for many proprietary preparations"?