Male (left) and female (right) of the longhorn beetle Macrodontia dejeani Gory, 1839 from Colombia; the Manchester Museum’s Entomology collection.
This species of longhorn beetles (family Cerambycidae) is rare in collections. It has a claimed range from Costa Rica to Ecuador and Peru but its heartland is Colombia. If 70 years of civil war and drug wars in Colombia is beginning to settle down, then perhaps more collectors will run collecting night lights there and more dejeani will appear. This beetle is named after General Pierre Dejean, a prominent figure in Napoleon army and a notable entomologist at the same time. The story of this eccentric man is told by Martin Laithwaite (Huddersfield, West Yorkshire).
Pierre Francois Marie Auguste Dejean (1780-1845)
Pierre “Auguste” Dejean was a soldier of fortune during the Napoleonic Wars; he became Colonel of the 11th Dragoons in 1807, General of Brigade in 1811, General of Division in 1814, served eight years as head of the Administration of War under Napoleon and was one of the Emperor’s aide-de-camps at the Battle of Waterloo. A prominent figure during the Empire, he is mentioned in Marshall MacDonald’s and Baron de Marbot’s memoirs.
He is also well-known for his five volume work on beetles and was one of the most important entomologists of his time. The Annals of the Entomological Society of France, vol. 2, p.502, 1845 relates that General Dejean, commanding the French army at the battle of Alcanizas was awaiting the attack of the enemy and noticed a rare specimen on a nearby flower. Jumping from his horse, he captured the click beetle, a Cebrio ustulatus, fastened it to a piece of cork, which he always carried under his chapeau for this reason, remounted his horse and won the battle.
The account was written by his private curator M. Boisduval “Before the battle of Alcanizas, which Dejean won after a long-contested fight, taking a great number of prisoners, when the enemy had just appeared and he was prepared to give the signal of attack. Dejean, at the border of a brook caught sight of a Cebrio ustulatus on a flower. He immediately dismounted, pinned the insect, applied it to the inside of his helmet which, for this purpose, was always supplied with pieces of cork, and started the battle. After this, Dejean’s helmet was terribly maltreated from cartouche fire; but, fortunately, he refound his precious Cebrio intact on its piece of cork.”
Most of the soldiers in his regiment learned to collect insects. Each carried a small vial of alcohol in which to place the insects he collected. It was claimed that even the enemy knew of Dejean’s eccentricity – those who found dead soldiers on the field having with them a little bottle containing insects in alcohol always sent the bottle to Dejean, regardless of who won the battle.
He amassed vast collections of beetles and listed 22,399 species in his cabinets in 1837—at the time, the greatest collection of coleoptera in the world. In 1802, he began publishing a catalogue of his collection, including 22,000 species names. Dejean was an opponent of the Principle of Priority in nomenclature. “I have made it a rule always to preserve the name most generally used, and not the oldest one; because it seems to me that general usage should always be followed and that it is harmful to change what has already been established”. Dejean acted accordingly and often introduced received popular usage names, given by himself to replace those already published by other authors; his names became invalid. However he is the authority for the family names of attractive popular well-studied beetle genera such as Batocera (family Cerambycidae) and Chrysochroa (family Buprestidae).
Dejean was president of the Société Entomologique de France in 1840. In 1834, he was elected a foreign member of the Royal Swedish Academy of Sciences. In later life, Dejean financed a number of collecting expeditions (particularly to what is now Panama and Colombia) and much of what he received was new to science.
Entomology Manchester 