It may be found that the thread is too slack in places to hold down the wings in proper position. That may be obviated by neatly cross-pinning down the thread on either side at intervals between the butterflies.
When all the specimens have been arranged with perfect uniformity, take two slips of tracing-paper, which have been previously cut to fit the length of the block, and each must be three-fourths the breadth of one side of the setting block. Then lay one of these strips of paper on the left-hand side, being very careful to keep just clear of the thread. All the wings will be seen plainly through the transparent paper and can be readjusted if any slip out of position. Next place with the forceps a No. 10 entomological pin firmly through the top and at the bottom of the paper, near the edge next the cotton. Place another between the first and second butterfly on the block, and so on down the row; also, _as you go along_, place another pin between the outer indentation where the upper and lower wings meet; also put a fourth pin by the tip of the upper wing. These pins should firmly secure the paper over the wings, which, when thus treated on both sides, will dry into the desired position for cabinet specimens. The greatest care must be taken not to allow any pin-point to enter the wing or fringe of a butterfly, or it will be quite spoiled. Next very carefully and gently undo the fastened thread, first taking out any cross pins which secure it. After its removal gently stroke from the body towards the paper on each side with a soft camel's hair brush any disturbed scales. With practice there should not be the least damage done by the thread, which leaves no mark whatever if _moved at once_ when the papers are firmly fixed. If they should be left on carelessly, or by any mistake, the threads will be certain to mark every butterfly, to their complete disfigurement.
Keep the blocks which contain the set-out butterflies in a dry cupboard or other safe place. When thus drying they fall an easy prey to earwigs, wasps, ants, cockroaches, and such like "small beasts," which will strip off all the bodies on a block in a single night. They should not be exposed to too bright a light whilst drying on the blocks, or they often suffer in colour. When single specimens have to be set out it is easy to work the thread by putting a pin through the knot and holding down the other end with the left-hand forefinger until the paper is fixed, and then treating the other wings in like manner.