One of the real joys of nightfall in autumn is the return of the katydids and their songs. Like our friend the field cricket, katydids produce sound with their forewings. One wing bears a structure called the scraper, which is pulled across a complementary structure called the file on the other forewing. The resultant vibrations produce the self-naming song of the katydid.
It is the male katydid that does the singing, all in an attempt to attract and woo a mate. The female katydid hears the song of the male through small openings, ears if you like, on her front legs. The sound enters through the slits and is amplified in a hornlike chamber within the leg. A membrane inside acts much like our eardrum and captures the sound. Sensory cells attached to the membrane pickup these vibrations and the female katydid’s tiny brain decides if he’s giving her good vibrations or not.
In addition to good vibrations, males of many species of katydids give their mate another type of gift, a nuptial gift, at the time of mating. This gift, called a spermatophylax, is a protein rich packet containing food and the sperm of the lucky katydid guy. Like all little sperm, the ones delivered in the packet fertilize dozens of eggs within the female katydid. As the sperm transfer to the female, she consumes the nutritious nuptial gift. One theory has it that by providing the she katydid with dinner and a date, the male enables her to produce more or larger eggs, thereby ensuring the birth of more of his own youngsters.
Egg-laying in katydids is a magnificent spectacle. The curved- tailed katydid bears a scimitar-like ovipositor on her rear end. This ovipositor is used to deposit flat, oval eggs in rows on plants, often beneath loose flaps of bark on trunks of trees. The eggs endure the winter when cold temperatures and lack of food make it impossible for plant-eating nymphs and adults to survive in places like Maryland.
A bush katydid uses her scimitar-like ovipositor to wedge eggs beneath a bark flap.
Katydids are also masters of disguise. Their exoskeletons produce shades of green that blend perfectly with vegetation on which they feed and rest. If you look carefully at their wings, you will notice the delicate network of veins closely resembling the veins of a leaf. This deception and their green coloration surely help them avoid detection by birds and other hungry predators that would find them a tasty treat. So in the waning days of autumn, keep an eye out and an ear open for the sights and sounds of these magnificent creatures.
Mottled green coloration helps this katydid nymph blend with surrounding vegetation.