174 BOARD OF AGRICULTURE. 



times over one hundred eggs in a single caterpillar. I have 

 repeatedly found the chrysalides of our common Antiopa 

 hutterfly filled with the minute white larvae of a Pterdmalus, 

 so closely packed that it seemed impossible for them to find 

 room to pass through their transformations. It is, however, a 

 well established fact, that in cases where insectivorous larvaa 

 find themselves too numerous for convenience or safety, they 

 will not hesitate to restore the balance by devouring their 

 brothers and sisters. 



The family Proctotrupidce of Stephens, comprises also many 

 minute species which are extremely beneficial to the agricul- 

 turist. One genus, Plalt/g-aster, is mentioned in Dr. T. W. 

 Harris's Treatise as attacking the Hessian fly ; and another 

 species of the same genus, (figure 47, Harr., 

 female magnified, the small cross lines at the right 

 show the natural size,) is found very commonly in 

 the egg of the canker-worm moth, and without 

 *'^'*'' doubt at least one-third of the eggs are thus 

 destroyed by this minute parasite. Figure 48, Harr., repre- 

 sents a cluster of the eggs of the canker-worm moth, of the 

 natural size, and five eggs at the right magnified. 



In the section of the Order Hymenoptera, 

 ^ of which we have been speaking, we find no 

 ^ highly concentrated poison secreted in glands 

 Fig. 48. at the base of the ovipositor, which is calcu- 



lated almost solely as an instrument for laying eggs, and used 

 only subordinately as a weapon of defence. We now come to 

 a division where this instrument is modified in its form, and 

 converted into a sharp needle-like apparatus, which contains in 

 a groove on its under surface two still finer and sharper weap- 

 ons, slightly notched toward the tips, and connecting with a 

 poison sac at the base in the females, as well as with the 

 ovaries. The poison is of an acid nature, so that when suffer- 

 ing from a sting of a wasp or bee, we find liquid ammonia, or 

 hartshorn, which is a strong alkali, to be an excellent antidote, 

 as it neutralizes the poison and relieves the pain. The antennae 

 in tliis division consist generally of thirteen joints in the males, 

 and twelve in the females ; the abdomen of seven joints in the 

 males, and six in the females ; the wings are veined, and the 

 larva) are footless. To this section belong the ants, wasps and 



