Top 20 Most Common Insects in Nantucket

H. sanguineus has a squarish carapace, 2 inches (50 mm) in width, with three teeth along the forward sides; its pereiopods are marked with alternating light and dark bands.

Thanks to its sapphire blue claws, blue crab is famous for its attractive appearance. Despite its lovely looks, the crab shows aggressive nature when it feels threatened. Blue crab has important commercial value and it's harvested for culinary use. Many people find its meat to be sweet and delicious.

The american Lady is a very unique-looking butterfly. From above, the pattern appears to be similar to a monarch butterfly (Danaus plexippus), but underneath the color is very different, almost like a moth's pattern. They even look different in different seasons — they have brighter colors early in the year and dull colors later. There are only a few populations of american Lady left in the world, which you can find along the coasts of North America.

The upperside forewings are a bright orange with a dark outside edge border and with eight or nine black spots. The hindwings are dark with an orange border. Some females also have a row of blue spots inside the orange border and are known as form caeruleopunctata. The undersides are patterned in a similar way but are paler. The black spots on the forewings are outlined in yellow and the dark colouring is replaced by a pale brownish grey. The hindwings are the same brown/grey colour with small black dots and a narrow orange border. The caterpillars (larvae) are usually green, but some have a purple stripe down the middle of the back and along each side.

C. maenas has a carapace up to 90 mm (9.0 cm) long and 210 mm (8.3 in) wide, but can be larger outside its native range, reaching 713 mm (28.1 in) wide in British Columbia. The carapace has five short teeth along the rim behind each eye, and three undulations between the eyes. The undulations, which protrude beyond the eyes, are the simplest means of distinguishing C. maenas from the closely related C. aestuarii, which can also be an invasive species. In C. aestuarii, the carapace lacks any bumps and extends forward beyond the eyes. Another characteristic for distinguishing the two species is the form of the first and second pleopods (collectively the gonopods), which are straight and parallel in C. aestuarii, but curve outwards in C. maenas. The colour of C. maenas varies greatly, from green to brown, grey, or red. This variation has a genetic component, but is largely due to local environmental factors. In particular, individuals which delay moulting become red-coloured rather than green. Red individuals are stronger and more aggressive, but are less tolerant of environmental stresses, such as low salinity or hypoxia. Juvenile crabs on average display greater patterning than adults.

The sachem (Atalopedes campestris) feeds on the nectar of many flowers, including milkweeds, peppermint, and red clovers. It often spends its time near pastures, meadows, roadsides, parks, and yards. The males spend most of their time on the ground, waiting for females to come.

Red admiral (Vanessa atalanta) is a visually striking species of butterfly. Unusually territorial, males will compete for choice areas, and females will only mate with males that maintain their own territories. This butterfly is known for being particularly patient with human interactions, even to the point of perching on clothing or flesh.

The silver-spotted skipper (Epargyreus clarus) constructs a series of nests throughout its development that depends on its growth stage. Its caterpillar form is considered a major homebody, as they rarely leave the spot they call home. When they are adults, males perch on high branches in order to claim and defend favorable territory. Unusually, silver-spotted skipper adults never visit yellow flowers.

Eastern tiger swallowtail (Papilio glaucus) is among the most recognizable butterflies in the eastern United States, where it inhabits a variety of habitats. This species is diurnal and usually solitary, preferring to fly high above the ground until the time comes to mate. Caterpillars display eyespots to deter birds in between some molting phases.

The common Buckeye (Junonia coenia) has distinguishable target-shaped spots on its dark wings, along with patches of orange and white. It produces multiple generations each year as it migrates to sunny landscapes. When it flies, it moves rapidly in an irregular pattern, often low to the ground.