An online resource based on the award-winning nature guide

Antennae

Harvestmen Harvesting

9-15-17 daddy longlegs2 049A3934Like their relatives – spiders, mites, ticks and scorpions – Daddy Longlegs, or Harvestmen, have eight legs (the second, longer, pair of legs are used as antennae). Of all the arachnids, spiders resemble Harvestmen most closely.  However, there are distinct differences between the two orders. Unlike spiders, the two main body sections of Harvestmen are nearly joined and appear as one structure. Harvestmen have no spinnerets nor do they possess poison glands. They also do not have the enzymes spiders have that are capable of breaking down the insides of their prey into liquid. Harvestmen ingest small particles, breaking them down with their chelicerae, or mouthparts, which resemble miniature, toothed lobster claws. One would surmise from this photograph that the legs of flies must lack the nutrition worthy of mastication.

 

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Spiny Witch Hazel Galls

8-26-13  spiny witch hazel gall 045Aphids are responsible for the formation of two different galls (abnormal plant growths caused by insects, fungi, bacteria and viruses) on Witch Hazel (Hamamelis virginiana). A cone-shaped gall forms on leaves and a second type of gall covered with spiny points grows from branches. The latter gall, referred to as the Spiny Witch Hazel Gall, provides many aphids (Hamamelistes spinosus) with both food and shelter while they are developing inside the gall. (Their two-year life cycle involves birches as their next host.) The pictured Spiny Witch Hazel Gall has split open enough to allow ants to discover and have access to the aphids. Once the ants enter the gall, they stroke the resident aphids with their antennae, stimulating the aphids into producing droplets of tasty “honeydew” from the tips of their abdomens, which the ants find irresistible. In return, the ants protect the aphids from predators.

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Clean Antennae Necessary for Sensory Perception

8-9-13 conehead katydid cleaning antenna 098Insect antennae are among the most sensitive and selective chemical-sensing organs in the animal kingdom. They detect information crucial to an insect’s survival, including odors, sounds, humidity, changes in water vapor concentration and air speed. Antennae are capable of these feats because of the sensory receptors covering them which bind to free-floating molecules. Experiments with cockroaches, ants and flies confirm that insects engage in antennal grooming — removing foreign materials from the surface of their antennae with their mandibles — primarily to maintain acute olfactory reception. Pheromones, chemical signals that are vital to insect communication, are used to convey alarm, attract a mate, mark territory and lay out trails, among other things, and clean antennae enhance these messages. (Photo is of a Sword-bearing Conehead Katydid cleaning its antenna.)

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