HOW TO KNOW THE IMMATURE INSECTS 



INSECT CONTROL. — The injurious insects give us a clear idea 

 of the importance of immature insects. It is the larvae of the Codling 

 moth, Carpocapsa pomonella Linne, for example which feed on our 

 apples, not the adult moths. The maggots of the Mediterranean fruit- 

 fly, Ceratitis capitata (Wiedeman), do serious damages to fruits, but 

 the adult flies except for laying eggs are quite inoffensive. Note also 

 the Gypsy moth, Porthetria dispar (L.), the Browntail' moth, Nygmia 

 phaeorrhoea (Donovan), and many Wire worms (Elateridae), White 

 grubs (Scarabaeidae), Cut worms (Noctuidae); their larvae cost us 

 millions of dollars every year. We need to know the morphological 

 structures, life histories and habits of the immature insects in order to 

 successfully conduct measures for their control. 



WHAT IMMATURE INSECTS LOOK LIKE 



EGGS 



Insects develop from eggs which differ greatly in size and shape in 

 different species. As a rule, insects tend to lay eggs proportionate to 

 their own size. The smallest known eggs are those of the CoUembola. 

 The eggs of one of the small headed flies measure 0.15 by 0.18 milli- 

 meter. The eggs of the clover seed midge and of the Tingidae are 

 also minute. The other extreme is found in the eggs of the giant silk 

 moth, those of the polyphemus moth being 3 millimeters in diameter. 



The shapes of insect eggs are described in the following: 



(a) Flat and scalelike (Fig. 7). — Take for example 

 the eggs of the codling moth and the orien- 

 tal fruit moth. 



Fig. 7. Eggs of the cod- 

 ling moth, Corpocopso 

 pomonella L. 



(b) Spherical (Fig. 8). — The eggs of many spe- 

 cies, such as the swallow-tail butterfly, the 



green June beetle and many other Scara- 



V -J 1. • 1 Fig. 8. Eggs of a 



baeidae are spherical. butterfly. 



(c) Conical (Fig. 9.) — The eggs of the imported 



cabbage worm, Pieris rapae (L.) and the 



_. _ t, , .. violet tip, Poiygonia interrogationis Fab., are 



Fig. 9. Eggs of the ■ i . v j , f -j j 



foil army//orm, conical m shape and deeply ridged. 



Lophygma frugiper 



do (Smith Cr 

 Abbott). 



