LETTEES FEOM ALABAMA. 
249 
SO imicli on the dimensions of the wings^ as 
on the size of the muscles that work them, which 
are contained within the thorax. The greater 
Dragon-flies rest with the wings horizontally ex- 
panded, as in flight; the smaller kinds [Agrio- 
nidce) bring their upper surfaces together, as 
butterflies do but the Myrrneleons close their 
wings, in repose, by bringing the inner edges into 
contact, the wings sloping down on each side like 
the roof of a house, in the position assumed by 
most moths ; and, when resting, they usually pro- 
ject the abdomen upwards, above the closed wings, 
at an angle with the body. 
The curious instincts of the larvss of these flies 
are well known. I have had no opportunity of 
verifying the received statements by observation, 
having met with the grub only on one occasion, 
viz. a day or two since. It was in the wall of an 
old out-house, among the clay between the logs. 
It ran equally well forward or backward, by little 
starts. I killed and offered it an ant, but it took 
no notice of it. I have often found that insects 
will not eat even their usual prey, if it be not 
taken by themselves, or presented in the circum- 
stances to which they are accustomed. Perhaps 
they do not trust the giver : 
Timeo Danaos, et dona ferentes.’* 
