The Small blue butterflies have a combination of black and silver wings with white outlines. They live in various habitats in England, Ireland, Britain, Wales, and Scotland, and their caterpillars are cannibalistic.
Small Blue Species Summary
| Scientific Name | Cupido minimus |
| Family Name | Lycaenidae |
| Kingdom | Animalia |
| Genus | Cupido |
| Habitat | Clearings, railways, woodland edges, embankments, abandoned quarries, chalk grasslands, limestone grasslands |
| Range | England, Scotland, Britain, Ireland, Wales |
| Host Plants | Field locoweed, alpine milkvetch, birdsfoot deervetch/common bird’s-foot trefoil, kidney vetch |
| Butterfly Description | Their underwings are lined with silver and black markings, and the wingspan is between 0.5 and 1 inch |
| Caterpillar Description | They are nearly white with a subtle hint of bluish tint when they hatch from their eggs |
Small Blue Butterfly Description
The male Small blue butterfly has a dark brown thorax. Its wings are covered in microscopic scales with dark blue shades and speckles. This blue speckling is absent in females.
Moreover, both sexes display distinctive silver-colored ventral sides with black spots. At the base of its wings, the male has a bluish color identical to the dorsal side (upperside). Their wingspan ranges from half an inch to an inch.
Comparison with Similar Species
The male Small blue butterflies are usually mistaken for the female Osiris blue because their color schemes are similar. Small blues are almost identical to Adonis blue, which have a sky blue shade on their wings. Finally, the Holly blues are similar to the Small blues as they both have a silvery shine. However, the Holly blue butterflies have bluish-silver wings.
Other similar blue butterfly species are Eastern tailed blue, Common blue, Spring azure, and Marine blue butterflies.
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| Osiris blue | slightly darker wings with a more prominent black edge |
| Adonis blue | slightly deeper blue shade |
| Holly blue | black forewing tips |
| Eastern tailed blue | darker wings with two orange spots on the end of the hindwings |
| Common blue | fluffier body compared to Small blue |
| Spring azure | prominent black forewing tips, thin line on hindwing edges with dark body |
| Marine blue | striped underside of wings |
Caterpillar Appearance
The first instar larva has a black head. Its thorax is covered in fine hair with a light blue shade that appears almost white. The caterpillar is barely a millimeter long once it hatches.
Once it reaches the second instar, it will be 0.16 inches (4 mm) long. The hair covering the thorax will appear thicker than the previous instar, and the thorax will become light yellow.
During the third instar, the fine hair will continue to become thicker. The shade will turn a deeper yellow at this point.
The caterpillar is around half an inch long when it develops to the fourth instar. It will have a stripe along the dorsal side of the thorax. After molting, its shade will be either pale green or pale yellow.
Once it reaches its full size, it will start to create its cocoon by spinning silk around its thorax. During this period, it will reach the chrysalis or pupa stage, lasting approximately 10 months.
Small Blue Butterfly Food Plants
The Small blue butterflies lay their eggs on these food plants:
- Field locoweed
- Alpine milkvetch
- Bird’s-foot trefoil
- Common kidney vetch
- Melilot (sweet clover, kumoniga)
- Burclover (medick)
- Cicer milkvetch (chickpea milkvetch)
Where does the Small Blue butterfly live?
The Small blue butterflies usually live in England, Scotland, Wales, and Ireland. However, their population is dwindling because of unsustainable practices related to their habitats. Numerous butterfly conservation groups are now involved in ensuring the Small blues are taken care of.
Small Blue Butterfly Habitat
These UK butterflies live in the following habitats:
- Clearings
- Railways
- Woodland edges
- Embankments
- Abandoned quarries
- Chalk grasslands
- Limestone grasslands
Small Blue Butterfly Flight and Behavior
Besides the regular food plants, the Small blues also get their nutrients, salts, and minerals from mud puddles, carrion, and animal dung. The males tend to be territorial, especially during the mating season. Females lay eggs on the host plants and leave the larvae to fend for themselves afterward.
Are Small Blues rare?
You may spot Small blues throughout many locations in the UK, but the distribution data shows a decline, so they are considered a relatively rare species. Their population decreased by more than 25% from 2005 to 2014.
3 Small Blue Butterfly Fun Facts
- It’s still unknown to experts why their population is declining.
- They overwinter, usually at the beginning of their life cycle.
- Adult females seem to favor the trefoils during ovipositioning.
Joan is a nocturnal person who loves traveling and coffee. She’s also an animal lover (and rescuer) who makes it a point to befriend every animal she meets. Her passion for learning led her to writing about various topics. As someone who is a nature lover, she aims to continue learning about the wonderful creation—especially butterflies, and at the same time, share her knowledge here at Butterfly Hobbyist.