Coenagrion hastulatum (Charpentier, 1825), the Northern Damselfly or Spearhead Bluet, is widespread and common in northern Eurasia but is restricted to elevated or bog-like sites towards the west and south. In Britain, it is confined to a few small lochans in Scotland. The specific part of the scientific name, hastulatum, from the Latin hastula (small spear) is because of the distinctive markings on the second segment of the abdomen that resembles a spear.

Coenagrion hastulatum is a smallish but fairly robust, black-and-blue species. It is 31-33 mm long. In the male, S2 has a rather variable, spear-head shaped spot linked rather like the cards "Spades" symbol. S8 and S9 are blue except for 2 small black spots on S9. The females are black and green, and are clear green from the side but mostly black from above. Coenagrion hastulatum's most distinguishing features include the spearhead-shaped mark on the male's S2 (which gives the species its scientific and common names) and the line which connects the fairly narrow, pear-shaped postocular spots (a feature which distinguishes it from its congener C. lunulatum).

This species is easily confused with the other members of the genus Coenagrion and with the Common Blue Damselfly Enallagma cyathigerum. Look at S2 (on the males) for distinguishing characters. Northern Damselfly is a weak flyer and has a very restricted range. The females can be particularly tricky to distinguish apart.

Coenagrion hastulatum is native to Austria, Belarus, Belgium, Bosnia and Herzegovina, Bulgaria, Croatia, Czech Republic, Denmark, Estonia, Finland, France, Germany, Italy, Latvia, Lithuania, Montenegro, Netherlands, Norway, Russian Federation, Serbia (Serbia), Ukraine, United Kingdom. It has experienced declines in parts of its central European range but it is widespread and abundant in northern Eurasia. There are a number of ongoing threats that will require the species to be monitored and studies are in place to do this. Therefore, it is accessed by IUCN Red List as Least Concern.
 

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