Ohservalions on Insects affect hig the Tnrni'p Crops. 311 



as soon as the caterpillar has cast off its skin, when it is both soft, 

 tender, and exhausted, so that it has not the power to exert itself 

 and frighten away the little parasites: the eggs soon hatch and 

 eat into the pupa, which at that early stage is almost liquid inside, 

 the members of the future butterfly not being organised. Some- 

 times 200 or 300 of these little maggots live in one chrysalis ; they 

 undergo their metamorphoses securely within the shell, and the 

 flies hatch and eat their way out in about fourteen days in 

 summer, but some remain through the winter, and when they 

 come forth they do not fly away, but hover in swarms about the 

 perforated pupa, the males probably hatching first and waiting 

 until the females emerge to be impregnated ; but after their bridal 

 dance, each female departs in search of recently formed chrysalides 

 to deposit fresh broods in. If we take 250 as the average 

 number of eggs which a female lays, and admit that one-half of 

 them are of that sex, the second generation would amount to 

 upwards of 30,000, an enormous increase, which is in all proba- 

 bility multiplied several times in the course of one season. Some 

 species of this extensive genus swarm even in our houses, es- 

 pecially in the country, where in October and November I have 

 seen immense numbers inside of the windows, and I believe they 

 hybernate behind the shutters, in the curtains, &c. The species 

 above alluded to is likewise Hymenopterous, and of the 

 Family Cyniptdj<;, or Ciialcidid^; it maybe the Ichneumon 

 puparum of Linnaeus, but as that is very doubtful I have 

 named it 



4. Pteromalus Brassicae.* Female dull blackish-green, thickly 

 punctured; head large, antennae clavate, black, basal joint 

 ochraceous; abdomen oval, depressed and pointed, black, shining, 

 bright-green at the base, with a violet tint beyond it ; wings trans- 

 parent, iridescent, with an ochraceous nervure along the upper or 

 costal margin of the superior, forming a short branch beyond the 

 middle ; legs bright ochre, coxae black, thighs, excepting the base 

 and tips, pitchy, apex of feet black; length 1 line, expanse 

 nearly 3 (fig. 13). 



The first broods of this little parasite hatch in April, and I have 

 bred multitudes of them from a chrysalis of Pontia BrassiccB. I 

 suspect the following insect will prove to be the male of it, differ- 

 ent as it is in appearance, having bred several from the pupa of 

 one of the White Cabbage-Butterflies many years since, when I 

 gave it the name of 



5. Pteromalus Pontia?. Male brilliant green, thickly punctured, 

 head brown, horns ochraceous, filiform; abdomen linear, con- 

 cave, apex ovate, very shining, often with a golden tinge ; 4 wings, 



* Guide, Gen. 627 and 641 ; and vide Brit. Eiit., fol. and pi. 166, Colax 

 disfar. 



