The appearance of small, shrimp-like creatures in yards, especially after rain, often raises questions about their nature and potential harm. This article clarifies what these creatures are and whether they pose any threat to humans or property.
What Are Lawn Shrimp?
“Lawn shrimp” are terrestrial amphipods, small crustaceans. Scientifically classified as Arcitalitrus sylvaticus, they are also known as grass shrimp, lawn prawns, or landhoppers. These creatures typically measure 0.2 to 0.8 inches (5 to 20 mm) in length, with a curved, segmented body that is often reddish-brown or pale pink. They possess two pairs of antennae and multiple pairs of legs, with some rear legs adapted for jumping.
These amphipods thrive in moist conditions and are commonly found in areas rich in organic matter, such as under leaf litter, mulch, and in garden beds. While most amphipods are aquatic, lawn shrimp have adapted to terrestrial life but still require significant moisture. They become more noticeable after heavy rainfall or overwatering, which can drive them from their habitats and sometimes lead them indoors.
Do Lawn Shrimp Bite?
A common concern is whether lawn shrimp bite humans. They do not bite people. These crustaceans lack the specialized mouthparts necessary to bite or sting. Their mouthparts are adapted for chewing and processing decaying organic matter, their primary food source.
Lawn shrimp are not aggressive and pose no direct threat to humans or pets through biting. While their sudden appearance in large numbers can be startling, their physical characteristics and feeding habits confirm they are harmless. Any perceived “bites” are likely from other insects or environmental factors.
Are Lawn Shrimp Harmful in Other Ways?
Beyond the concern of biting, lawn shrimp are generally considered harmless to humans, pets, and most plants. They play an important role in the ecosystem as decomposers, breaking down dead leaves, fungi, and other decaying plant matter. This activity contributes to nutrient recycling and healthy soil in gardens.
While not harmful, lawn shrimp can become a nuisance if they enter homes or garages, especially when seeking refuge from overly wet outdoor conditions. They often dry out and die quickly indoors, as these environments lack the high moisture and decaying organic matter they need. Managing yard moisture, such as avoiding overwatering and removing excess organic debris, can help prevent them from becoming an indoor issue.