constant values of SFR of 100 and 5 $M_{\odot} yr^{-1}$. Red symbols are  and black ones are .[]{data-label="fig:ssfr1"}](pentericcifig4.eps){width="11cm"}

MIPS detection and IR-determined SFR
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At redshift $\sim 2.4$ the mid-IR (5–8.5 $\mu$m) features associated with PAH emission, which are ubiquitous in local and z$\sim$1 star-forming galaxies, are shifted into the MIPS 24$\mu$m filter. We searched for counterparts of our LBGs in the GOODS-MUSIC 24$\mu$m MIPS catalog (see Santini et al. 2009 for details). Note that galaxies with mid-IR excess such that the MIPS flux is probably due to AGN activity rather than star formation (see also Fiore et al. 2008 for the proper definition) are flagged as AGNs in the revised version of the GOODS-MUSIC catalog that we are using and therefore were excluded from our initial sample selection (see also Section 2). Therefore we assume that the 24$\mu m$ flux is due to star formation.\
We found a total of 39 objects with clear detections. Of these, 12 are  and 27 are  indicating that the detection rate of  is more than double, compared to the line emitters. As expected the subset of MIPS detected sources is on average brighter (in z–band) and at a slightly lower redshift than the 