HOW TO KNOW THE IMMATURE INSECTS 



lay their eggs is a complicated one, but very interesting. Insect eggs 

 are generally laid in situations where the young, upon hatching, may 

 readily find food. Species that feed upon foliage usually lay their 

 eggs upon leaves of the correct plant. The ability of adult to recognize 

 the right species of food plant for its offspring often seems remarkable. 

 Aquatic insects lay their eggs in or near the water. Parasites general- 

 ly lay their eggs upon or within their host. Some flower flies lay their 

 eggs in clusters of aphids or other soft-bodied insects. The Mallophaga 

 and Anoplura lay their eggs upon the hair or feather of their hosts. 

 There are also many special cases. Some insects lay their eggs upon 

 foliage or in the ground and the young are compelled to seek their 

 hosts. The twisted-winged insects (Stylopids) often lay their young 

 upon plants where they must wait until certain solitary bees visit these 

 plants. The young then grasp the legs of the bees and are carried to 

 nests where they find theii hosts. The eggs of walkingsticks lie dor- 

 mant beneath leaves or other debris upon the ground. With the ap- 

 proach of Spring, the eggs hatch and the nymphs must find the leaves 

 of their host plants. Insects such as leafhoppers and aphids, many of 

 which feed upon herbaceous annual plants during the summer, seek 

 woody plants on which to lay their eggs when winter approaches. 

 Many leaf-mining insects of the orders Lepidoptera, Hymenoptera, 

 Coleoptera and Diptera insert their eggs into wood, leaves, fruits and 

 seeds, thus offering ready access to food for the young when they 

 hatch. The Fruit Flies and many Snout Beetles insert their eggs direct- 

 ly into the fruit in which their larvae will develop. The tree crickets, 

 treehoppers and leafhoppers lay their eggs within woody plants for 



protection of the eggs. Some 

 Chalcids oviposit in seeds. In- 

 sect eggs are sometimes car- 

 ried by the adult for better pro- 

 tection. The Hydrophilid beetles 

 of the subfamily Sphaeridiinae 

 carry the eggs attached to their 

 hind legs. Certain Mayflies 

 may carry two eggs adhering 

 to the posterior end of the body 

 - until opportunity is found to 

 drop them into the water. 

 a, Mantid; b, cross-section Reaches often carry an egg 

 c, phosmid; d, ^^gg (ootheca) at the tip of the 

 abdomen. The females of the 



Fig. 15. Oothecoe 



of mantid ootheca 

 German cockroach. 



8 



